| Author | Message | ||
     Brian Vogel Grand Master Username: guyslp Post Number: 1269 Registered: 6-2009 |
I've been poking around in the Workshop Manual in an attempt to determine what the actual function that electric fan in front of the radiator performs and what the "turn it on" triggering mechanism is. I've not been having much luck. Chapter L2 gives brief instructions on how to remove and fit it. Given that the cooling capacity on these cars is more akin to that of a large diesel truck, and if they're working as designed there's barely a need for the main cooling fan during most driving faster than stop-and-go, I'd always thought this thing was related to giving a boost to cooling the condenser coils for the climate control, but even this seems completely unnecessary except on very hot days when you're barely moving. Does anyone know where the "purpose description" and "how you test it" parts related to this fan can be located? Brian, who needs to keep doing OCR conversions to make this sort of search easier | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1369 Registered: 6-2006 |
It should come on when the thermostat housing reaches about 102 (ish) Celsius. Otter switch in housing. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1275 Registered: 6-2009 |
Paul, Thanks very much. I'm curious if the workings of this thing are well documented anywhere in the Workshop Manual or other Service Bulletins. If you happen to know where the information on this subsystem is located please let us know. I recall seeing "the bump" shown in the picture below when I was replacing the thermostat on LRK37110. Clearly it's the switch under that bump.  Brian | ||
| bob uk Unregistered guest Posted From: 92.40.249.229 |
Don't forget the relay. The otter switch is not strong enough to run the fan direct. (Message approved by david_gore) | ||
| Hansen Unregistered guest Posted From: 75.61.74.205 |
Re: "It should come on when the thermostat housing reaches about 102 (ish) Celsius." I have been concerend that my MPW Coupe CRX2541 is "running too hot" when the thermostat housing/bypass is at 210F (100C) and also as indicated on the temp gauge at right at the top end of the white band, rather than in the middle where there are two "dots" that I had assumed to be the "desired" running temp. Does Paul's comment indicate that 210F is NOT running hot and that the gauge may simply be reading incorrectly? (Message approved by david_gore) | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1287 Registered: 6-2009 |
I have always been told that the entire white band on the gauges of these cars is considered to be "within normal operating limits," though it should only be in extreme ambient temperature conditions coupled with stop-and-go traffic driving where it should reach the top of the white band. I've experienced that once or twice when the ambient temperature was 90 degrees F (ish) and I was caught in stop-and-go traffic with the AC on. Even if the AC was turned off, it didn't go down much at all under those conditions. It would be interesting to have a collection of "top of thermostat housing" temperature readings under a range of operating conditions. Since I don't have an IR thermometer I've never done that on my own cars, but it would be good to know what people are actually experiencing "in the field" and also knowing whether their cooling systems are known to be "clean as a whistle" or "likely in need of a cleaning." We certainly have the cars out there, whether we have the IR thermometers or the will is another thing entirely. Brian | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1370 Registered: 6-2006 |
Hansen, Hi, under what conditions does your temperature rise to that level and how much time does it spend there? Is it when cruising or sitting in traffic? Where are you in the world and what are your ambient temperatures? I would be concerned if I were you and do a few checks. In an ideal world with a new transmitter and an accurate gauge it should indeed be sitting fairly near the middle. Transmitters do fade , but tend to go towards the cold side more often than not. Is your viscous coupling locking up correctly? When everything is as hot as it ever is, open the bonnet, watch the fan, rev the engine to about 2000 revs and then turn off the engine - the fan should be fairly locked up and stop quickly not free wheeling. Are the fins in your radiator clear of insects and debris. Is your thermostat the correct type that shuts off the by-pass when it's open? | ||
| Hansen Unregistered guest Posted From: 75.61.69.153 |
Paul... Thank you for your reply. I will try to provide a synopsis of the circumstances, but I should also note that since this discussion is not entirely related to the original thread, forum protocol may require that a new thread be initiated. However, as a guest poster, I am not certain how such should be accomplished and will simply beg forgivness if I am on the wrong side of those rules. As to your questions, the environment is the temperate climate of the San Francisco inner Bay Area where summer temps range in the F70s in Summer and F50s in Winter. I inherited this issue from the prior owner who had installed a Crewe pellet type thermostat which I verified as operable with the hot water in pan check test, and yes, it is the type that shuts off the bypass back to the water pump when it is open. Radiator was recently removed and rodded which resulted in absolutely no change in the symptoms. A home devised flow test indicated that the "rodded" radiator reduced flow by 50% so a new heavy duty core with dimpled tubes was installed which merely brought the operating temperature down by ten degrees from 220F to 210F. I have not repeated the flow test on the new core to compare its flow rate as I can see no virtue in doing so. Suffice it to say, the radiator does not seem to be the problem. While the fan clutch appears to have the symptoms of operating properly, i.e. speeds rapidly upon cold start, slows down after a few minutes, speeds up agains when the coolant temperature gets to the high range, and upon shutting off the engine, continues to revolve by perhaps no more than a single revolution. On the other hand, it is entirely possible/likely that it is still not operating completely up to proper capacity given that it is almost 50 years old and odometer shows about 75,000 miles and although there is no clear evidence of oil leakage, there should be no surprise that a certain amount of oil has indeed seeped thru the seal and thus a rebuild or replacement may be in order. That said, the circumstances and symptoms do not give any credence to the proposal that a lack of air flow may be the cause. I will come back to this comment in a moment. As to the operating conditions, I would first characterize the problem as one of simply the operating temperature running too hot, but once up to that point, it remains static without continuing to the point of overheating catastrophically. Until I actually purchased a professional grade IR heat gun to verify the running temps at various engine bay locations, I almost had myself convinced that the engine was not actually hot and that the sending unit and/or gauge were faulty. Unfortunately the evidence provided by the IR heat gun dispelled that hope. I live in a district in the hills about 3 miles from the village where gas station, post office, bank, and grocery store are located and where the final half of that distance is level. I have a home business and only infrequently travel beyond these parameters and thus have been able to tolerate the "running hot" problem. Upon starting the MPW, and once the fast idle has dropped away, the journey into town is basically without engine load as it is downhill and then level. The coolant is seldom hot enough to even open the thermostat upon arrival in town. However, the return trip, being first level and then uphill, is when the coolant temperature begins to rise from what would otherwise be "normal" i.e. the middle of the white band on the temperature gauge, and increasing to the very top of that band, by which time I am home and the engine is turned off. Since the "running hot" condition is experienced only for the last several hundred yards or so, I have considered the condition to be tolerable while I am trying to determine the actual cause. I should note that I also have an EPW Silver Dawn, a Silver Cloud, and a Silver Spur which when operated in precisely the same conditions hold a coolant temperature that is right at the thermostat opening range and the rigidly holds that temperature without continuing to rise as does the MPW. On those occasions where I need to go further on some other errand, the entrance to the highway is also about the same 3 miles away and downhill. Over the first 5-10 miles or so at highway speeds, the temperature slowly rises to the "normal" range on the gauge and then very slowly creeps upwards. If I then get into street traffic where speeds are lower, the temperature will continue to rise to just below "Hot" but no further. What is notable is that once the coolant heats up, it never recovers. Getting back on the highway and the airflow provided by those speeds has no mitigating effect on the gauge temperature. It is for this reason that I tend to discard the theory that the fan clutch may be at fault for were the issue simply one of inadequate airflow, that result "should" have been provided by the flow of air over the radiator at 60-70 miles per hour of travel. Since providing air flow by simply "going fast" has no effect on the condition, air flow does not seem to be the issue. "Cut to the Chase": Is it possible that the water pump is defective to the point of not providing sufficient flow of coolant to the radiator? My theory is that three features are necessary to achieve proper cooling: air flow, coolant flow, and the ability of the radiator to transfer the heat from the coolant to the air. The new core eliminates the heat transfer issue and the travel speed would seem to eliminate the air flow issue which leaves only coolant flow. If the coolant is not flowing to the radiator, it cannot benefit from the airflow and will not be cooled. This baits the question of what is "normal". When younger, I was part owner of a Ford Model "A" restoration shop. The Model "A" coolant system is very basic and the water pump works exactly like an inline pump such that the oldtimers could actually use a running engine to pump water. If the return hose to the radiator is removed, water will be forcefully pumped out as a geyser and rapidly deplete the water in the radiator. While checking on the status of the thermostat in the MPW, I had occasion to make observations and conduct an experiment that had inexplicable but perhaps pertinent results, depending upon what is "normal" for the RR Coolant flow design. When the thermostat housing top and thermostat were both removed, and based on my Model "A" experience, I fully expected that upon starting the engine water would gush from the open thermostat housing, but in fact NOTHING happened!! Instead what I observed was what appeared to be a vortex in the coolant in the housing that upon examination was simply the water cycling down the bypass back to the water pump, which upon brief though was not surprising since such is the flow when the thermostat is closed, that is, the water flows from the engine into the thermostat housing and then directly into the bypass opening, but when the thermostat opens, it closes off the bypass orifice and "in theory" the water should then pass thru the open thermostat towards the radiator. To mimic this action, I simply reached into the thermostat housing and closed off the bypass orifice with my thumb. To my surprise, STILL no water was being pumped out of the housing!! Bizarre, I thought. That is when I noticed that due to the angle of my sight, I had not noticed that there was yet ANOTHER exit orifice in the housing which served to bypass coolant into the intake manifold area, presumably to assist with warming the intake gas/air mixture. The observed issue was that even with the water pump bypass closed by my thumb, there was still not enough coolant flow to exceed that capacity of the manifold orifice to drain it away, leaving in the net none to be passed to the radiator for purposes of cooling. The question is "Is this NORMAL" or does it indicate an under-performing water pump?? The water was by now getting too hot to be fussing with, but I did one last test and found that by bringing the engine rpms up significantly, enough flow was generated such that at least "some" but not a significant amount of water did flow out of the housing. Bottom line is that I throw out the question again: "Is this normal?" I then sourced a length of clear plastic tubing and from an old upper radiator hose fabricated a "sight glass" to observe coolant flow under operating conditions. I found that with everything put back together, there was no observable coolant flow back to the radiator with the thermostat closed, as would be expected, but that as the coolant temp increased, and as verified with the IR heat gun, such that as the thermostat began to open, coolant also began to flow past the clear sight tubing. The problem however was that it was not possible to determine the volume of that flow, other than it "seemed" to be "more" than what was ejected from the housing with the system in an "open" state, i.e. with the top of the housing off and the thermostat removed. Is it possible that as opposed to the Model "A", the RR system does not function as an inline pump and requires a closed system to function? The bottom line is that my suspicion is that, for whatever reason, there is not sufficient coolant flow traveling to and through the radiator such that even with the airflow provided at highway speeds, the indicated temperature never recovers. Is this possible?? I apologize if I have perhaps "made a short story long". What do you think?? I am most grateful for your indulgence and any ideas that you can propose or tests that can be suggested. If I may paraphrase someone else's comment: the problem is simply that the cause has not yet been discovered. Thank you! (Message approved by david_gore) | ||
| Jonas TRACHSEL Frequent User Username: jonas_trachsel Post Number: 63 Registered: 2-2005 |
Hansen You write: "My theory is that three features are necessary to achieve proper cooling: air flow, coolant flow, and the ability of the radiator to transfer the heat from the coolant to the air." Thereby you forget the fourth condition, namely to transfer heat from the engine to the coolant. As an owner of a prewar car I am fully aware of many engines having badly sludged-up cooling channels with rust and scale in the block and cylinder head to the point of a) restricting cooling flow and b) restricting heat transfer to the coolant Rust should not be an issue in an aluminum engine, but deposits from very hard water could build up to the point of impeding heat transfer. Remember your household boiler needing descaling from time to time, as even a few millimeters of scale reduces efficiency remarkably. So what now: There are other threads abounding giving good tips how to descale a cooling system, search the forum for "descaling". Jonas | ||
| bob uk Unregistered guest Posted From: 188.29.164.184 |
All engines are eventually air cooled. My engine complete with genuine stat. Never overheats. Dorset temps are between minus 2 c and 30c. I would put some Holts rad flush in. And or connect cooling system to water mains and flush for 1 hour. Using an temp gauge check core for cold spots. It is possible for the water pump impellor to fall off. Very rare. To check remove stat and elbow. Water should squirt out on the starter only. All makes and models. This system has had the snot tested out of it and its very good with spare capacity. (Message approved by david_gore) | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1374 Registered: 6-2006 |
Hi, firstly the pump will cavitatE if air gets in there. so thermostat housing off is not a good test. I have a top hose with a hole on the top half way along. With a garden hose replenishing the coolant level, water should push out of the hole with some Force. On older type top and bottom hoses you can also feel or see them get hard as the engine is reved up. I'm not sure what temp is normal . . I usually put my hand on it and decide. 40 years ago we didn't have iŕ thermometers!  Happy to lend it to you if you pay the shipping costs. Have you tried a new temp transmitter? Have you run with no thermostat? Is mixture rich enough and timing ok? I will take a few temp readings out of interest. Excuse the typos. I'm on the phone. :/ | ||
| bob uk Unregistered guest Posted From: 94.197.121.239 |
The idea is just to flick the starter if the impellor is turning then the water will move. If impellor has fallen off then no water moves. I dont run the engine just a flick on the starter. I have used the water pump on some cars to remove coolant to make room for antifreeze. Usually by disconnecting a heater hose and running the engine. Water pumps seldom stop pumping water as long as the pump impellor turns. Leaks and bad bearings dont stop the pump pumping. In general car water pumps have far more pumping capacity than is needed. A fire engine pump is about twice the size of a Shadow pump. So rest assured if the impellor turns then the pump will work. I must stress that I have only seen one pump impellor detached in 50 years of spannering cars. I suspect that the pump had been reconditioned badly. As Paul Yorke said the pump can be felt as the engine is revved. Sometimes the top hose can be seen to flex on some cars. These checks are quick and standard fare for a mechanic. The sort of thing that the mechanic notices in the first minutes of checking out a over heat problem. (Message approved by david_gore) | ||
| Hansen Unregistered guest Posted From: 75.61.67.191 |
Gentlemen...Re: Engine running hot on 1968 MPW Coupe CRX2541: Thank you for your ideas and suggestions. There are a lot of ideas to address and I will start will only a few for the moment. I am rather fixated on the "possibility" that the water pump is not pumping up to capacity and would like to devise some sort of test short of simply pulling it off and replacing it. While that is something on my "to do" list since I rather suspect the existing water pump is the older variety with the "prone to catastrophic failure without warning" seal and I would like to upgrade it to the new version with the allegedly more dependable seal, my budget for simply throwing money at the car in hopes that the "running hot" problem will go away is regretably limited. If I do go that route, I suppose that the worst that will happen is that I will have the upgraded water pump, a depleted bank account, and an engine that still runs hot! As to the "cavitation" issue, yes, I thought about it, but cannot see how it could be the cause of water not pumping out of the top of the thermostat housing forcefull, or at all at idle, since when the top of the housing is off and the thermostat is removed, the level of the coolant simply falls to that level, but not down to the level of the pump. Basically the water that was previously in the separate expansion tank flows out and the new coolant level is established where the top of the housing is about level with the top of the radiator core. On the other hand, with the water pump being towards the middle, if not the lower portion of the engine, it is still submersed by at least 6" or more of water, so I do not see how air could get to the pump to cause cavitation. Under these circumstances where the pump is beneath the surface of the water, if the engine is turned on, the pump, being surrounded by water and not air, should act like an inline pump and draw water via the lower hose from the radiator and eject it from the top of the thermostat housing. Since that does not happen, may I suggest that caviatation is not the reason, but rather something else? As to the test of a hole being in the top of the upper radiator hose, that is very similar to the test with the top of the housing off, except that the level of the water will be about 2"-3" higher. Also, it would seem that such a test would only be effective if the thermostat were removed, since water will only be pumped out of the housing and into that hose when the thermostat is open and the addition of the cool water supplied by the water hose will bring the temperataure down sufficiently so as to close the thermostat. The complication is that if you remove the thermostat the bypass will constantly be open and the water pump will have to provide sufficient flow such as to exceed the capacity of both the bypass to the water pump in addition to the bypass to the intake manifold before any is available to pass to the radiator. If in fact you have done this test with the thermostat removed and water does indeed gush from the hole in the top of the upper radiator hose such that you have to replenish the system with a garden hose lest it run low, then my desire to determine "what is normal" is answered by the fact that "normally" water should gush from either the top of the open housing or the hole in the top of the radiator hose, and the fact that it does not in my case is rather indicative of the fact that my pump is not creating sufficient flow. Yes? No? As to checking temperatures, I curently am using one of those $50 infrared heat guns. Originally I thought about the temp sending unit being defective. I fantasized that the engine was actually NOT overheating and that the temp sender was simply sending the wrong information to the gauge. Unfortunataely on the early Shadows the sending unit is rather awkwardly placed at the rear of one of the head banks and up against the bulkhead rather than conveniently located in the thermostat housing. Rather than fuss with replacing it, I spent the $$ to buy the heat gun. Upon discovering that yes indeed the bypass elbow was reading at 220-230F on a 75F degree ambient temperature day, that dispelled any illusion that the temp gauge was at fault and convinced me that yes indeed the engine was running hot, the problem was real, and something had to be done. A brand new radiator core later, I still have the problem except the new core brought the running temp down by a bit to 210-220F, ergo, the radiator is not the problem, but rather something else. Thoughts?? (Message approved by david_gore) | ||
| bob uk Unregistered guest Posted From: 94.197.121.239 |
I think the pump should be removed for a check that nothing is obstructing it somehow. The water comes from the bottom hose to the pump. Any thing wrong with the suction side including the bottom hose will impair the flow greatly. Water pumps have no bits apart from seals and bearings that wear. The correct colour for the pump is black so a flick over with black aerosol makes them look nice. The impellor and drive flange are locked together and should turn as one. So grip flange in vice and the impellor should not turn, locked solid. The aircon rad should be checked so that debris is not impeding airflow to the main rad. The vicious coupling for the fan can be checked by holding the fan with a hammer handle and then rev the engine when the hammer is removed the fan should go whoosh as the fan picks up. When the car is moving at say 30mph the natural air flow will exceed the fan and the fan is along for the ride doing nothing. The engine should run at 90c. With brief 100c running ok. Water pumps as stated are simple pumps that will work fine with dodgy bearings and seals. Washing machine pumps work the same. (Message approved by david_gore) | ||
| Hansen Unregistered guest Posted From: 75.61.64.245 |
Hmmm... Thank you all for your replies and input. Sounds like "normal" is that with engine running, water should be gushing from the system, and that my symptoms are therefore not a "normal" coolant flow through the engine due to either pump issue, or some sort of obstruction. As noted, there is a new radiator core and bottom hose was replaced at same time, so only other place for problem location is within the engine. I will do my home grown flow test on the engine only prior to removing the pump to establish a base line for later flow rate comparison. While we are discussing "normal", what is the water line noted in the attached photo and its purpose? Photo was taken during the radiator change, with bonnet, radiator, and fan off. The mystery hose goes from water pump (outlet side I presume) to top of radiator (but not the separate top tank). In the photo it is folded back out of the way. Function is, I presume, to have a direct, if reduced, flow of coolant to the radiator that bypasses the engine and thermostat route. I also assume that with the engine running, coolant should be flowing under force from the pump into the radiator via this hose and that is the "normal" for this hose? If so, that also indicates a problem symptom because when I disconnect it at the radiator end, NOTHING comes out, perhaps further pointing to a coolant flow problem. Yes? No? Thanks again to all. Christian Hmmm...seems like the photo will not upload even after reducing the size. Get error message saying that the file size exceeds the the maximum allowable size of...drum roll...-1Kilobyte...yes, minus one Kilobyte. How do you make a file size that has a negative value? Help? Brian, this is your forte. Ideas? (Message approved by david_gore) | ||
| Hansen Unregistered guest Posted From: 75.61.64.245 |
Oops...my error. I was confused. The mystery hose connects to the top expansion tank, NOT to the radiator as indicated in the prior message. I have a photo, but it will not upload. What is the purpose for the hose? What is the direction of flow? I assume it originates at the pressure (output) side of the pump and sends water to the top tank, or is this wrong? (Message approved by david_gore) | ||
| David Gore Moderator Username: david_gore Post Number: 1601 Registered: 4-2003 |
Hansen/Christian, You have to register as a member of the Forum before you can upload photos/images. Guests do not have this privilege. The preferred image size is 640 x 480 pixels in landscape orientation and 480 x 640 pixels in portrait orientation to avoid having to scroll the computer screen to view the entire image. | ||
| Hansen Unregistered guest Posted From: 75.61.72.238 |
David... How is registering done? Weeks ago I intitated the process with username "Enquiring Mind" but have hear nothing since other than an intital email saying the the application was under review and that I would be notified either way. Subsequently wrote emails to admin, even the President, and got no replies. Status report when I try to log in says that my account has been suspended, which is odd since I have never had an account, or at least do not recall having an account. Any way of telling what is going on? (Message approved by david_gore) | ||
| David Gore Moderator Username: david_gore Post Number: 1602 Registered: 4-2003 |
Hi Hansen, Have forwarded your post to our Administrator who is solely responsible for approving registrations. Did you receive an email with a link to activate your membership? These have a limited validity and lapse if not activated in time. If it has lapsed, you will have to resubmit under a different user name and I suggest you submit a new registration application. It is possible your email account may have classified the Administrator's activation email as spam and diverted it to your Trash or Spam folder meaning it was overlooked and expired. After submitting the new Application, please ensure you check your email Trash/Spam folders daily in case this diversion has occurred. David | ||
| Christian S. Hansen Yet to post message Username: enquiring_mind Post Number: 1 Registered: 4-2015 |
David... Thank you for forwarding my status inquiry which effort seems to have been successful as approval was just received via my email. Christian | ||
| Christian S. Hansen New User Username: enquiring_mind Post Number: 2 Registered: 4-2015 |
Here is the photo of the mystery coolant line I tried to post earlier. Any information as to its intended function? Is the direction of flow from water pump housing area towards top tank? Is it under pressure from the water pump? And finally...if disconnected at the top tank end and with engine running, should coolant spurt out? | ||
| Christian S. Hansen New User Username: enquiring_mind Post Number: 3 Registered: 4-2015 |
1968 Silver Shadow MPW Coupe CRX2541  | ||
| Jeff Young Prolific User Username: jeyjey Post Number: 214 Registered: 10-2010 |
Christian, That's the primary feed line from the header tank to the rest of the cooling system. There's not really a "normal" direction of flow: when you fill the system the coolant runs down this hose into the engine/cooling system. When the engine/coolant warms up, expansion will drive a little bit of coolant back up this hose into the header tank. But at steady state running, there shouldn't be any movement to speak of through this hose (ie: it's not part of the cooling "loop"). As such, the hose will be under the same pressure as the rest of the system (due to heat & expansion), but won't be under any pressure from the pump specifically. With a cold engine on tick-over, I wouldn't expect to see any fluid coming out this hose if disconnected. Note that there's a second smaller hose between the front of the header tank and the radiator. That can also transfer coolant in either direction, but it's main purpose is to purge any air trapped in the top of the radiator back up to the header tank. Cheers, Jeff | ||
| bob uk Unregistered guest Posted From: 188.29.164.74 |
Excellent photo of a nicely presented engine. (Message approved by david_gore) | ||
| John Kilkenny Prolific User Username: john_kilkenny Post Number: 193 Registered: 6-2005 |
See Tee One Topics Issue 61, Page 868. | ||
| Christian S. Hansen New User Username: enquiring_mind Post Number: 4 Registered: 4-2015 |
Voila! Bob...Thank you for your compliment on the MPW. It really is a splendid vehicle and the pleasure will be so much enhanced when I no longer have to fixate on the temperature gauge running just shy of hot. John...Thank you for the reference to the TeeOne issue for it served to provide me with that "aha" moment. When confronted with a problem, it is my temperament to try and understand the circumstances, study the symptoms, try to visualize a theory as to the cause of those symptoms, and devise tests to verify/discard that theory prior to embarking on any serious or costly remediation. In doing so, one's observations and tests either confirm or refute what is normal or abnormal, but in order to do so it is necessary to first understand what is normal, hence the purpose of this thread. Not knowing any better, it was my theory that the noted line was on the pressure side of the pump which baited the question of why coolant did not gush forth when the line was disconnected and was that normal. The diagram and text of the TeeOne article showed the error of that theory and also provided the answer to not only that question, but also the one of why no coolant gushed from the thermostat housing when its top was removed and the engine running. Since that line is actually connected to the input side of the pump circulation, when disconnected from the top tank it actually should exhibit a bit of suction. Of more relevance, this provides the answer to the thermostat housing issue. Cavitation had been proposed as a likely cause, but I queried just where that air was coming from since when I covered the bypass orifice in the housing, still no fluid gushed forth. Answer is that the air comes from THIS line!! When the top of thermostat housing is removed, the excess coolant flows out and the coolant level is re-established down to the level of the top of the housing. The top tank is now empty of coolant and filled with air. When the engine is started, since that line is connected to the input/suction side, air is draw down that line and creates the air cavitation which prevents the pump from drawing from the lower hose of the radiator and thus is incapable of pumping any volume out of the thermostat housing. Voila! Question answered! My question was, is it normal when no coolant is pumped from the housing with top removed and engine running. Answer is "yes" and the suspicion that the pump is defective is therefore likely unfounded. Theoretically if this analysis is correct and that line is removed from the top tank and plugged, the source of air should be eliminated, negating the cavitation, and the pump should be able to draw coolant from the radiator and eject it from the open housing. I will now have to repeat this test and others that have been suggested privately to see what happens. Regrettably, while this does resolve the suspicion that the water pump is a contributing factor, I am not really any closer to the determination of whether in fact there is less than ideal coolant flow due to some as yet unknown reason, or if the running hot condition is caused by something else. At least I am chipping away at the problem. The next "is this normal" question has to do with the viscous fan clutch. The observation is that once in town driving causes the coolant to get hot (200-210F) getting onto the freeway and driving at 60-70 mph and the resultant air flow over the radiator does not result in the coolant temperature falling back to the normal range even with new radiator core and the A/C core is free of insects or other obstructions. Bob ventured that in this case (over 30mph?) the fan is not the major source of air flow, but rather the forward movement of the vehicle. Is he correct, or should I fall for the expense of replacing the viscous coupling anyway to see what happens? Ideas? Thanks!! | ||
| gordon le feuvre Frequent User Username: triumph Post Number: 73 Registered: 7-2012 |
The way to test viscous is to FIRSTLY make sure car in PARK then remove gear selector isolator. Start car from cold (in ventilated area)let choke come off by it's own accord. Do not kick revs off as choke opens. What you are looking for is fan will "roar" for minute or so, whilst wax in viscous drags, then go quiet. Once engine been running 10-15 mins on fast idle(1800rpm) you will be able to hear viscous start to work as airflow heats wax to liquid and this then drives fan like a turbine. The fan roar will get audibly louder as fan starts to drive instead of just wind milling around. This is "shop" test. REMEMBER to kick off choke at end of test before turning off. DO take time to find gear selector isolator and remove. I have seen LOTS of Shadows/Spirits where owner has knocked selector with engine running and cars have hit something. | ||
| Christian S. Hansen New User Username: enquiring_mind Post Number: 5 Registered: 4-2015 |
Gordon... Thank you for that procedure to which the fan appears to comply, as well as when hot after a drive, upon turning the engine off, the fan only continues to spin for less than a full revolution, both of which appear to indicate that the fan is functioning as intended. Just the same, with a 50 year old device with 75,000 miles, it would not be surprising that a certain amount of the fluid has seeped out thus to some extent compromising its full potential at least to some extent, thus there is theoretically room for improvement, yes?, no? However that is not the real crux of the question, which is why the coolant temperature does not moderate from the HOT position back to the normal position on the gauge due to air flow created either by the fan at lower speeds or by 60mph forward movement. I am trying to determine theoretical reasons for this observed condition. Ideas? | ||
| bob uk Unregistered guest Posted From: 92.40.249.85 |
Good advice from Gordon, further to Gordons posting. start engine with a hammer handle stalling the fan. You should feel drag rev engine to say 1200 rpm then release the fan double quick time. The fan should go whoosh, with a satisfactory blast of air. That fan certainly can shift the air. Please take note about gearbox cutout. The circuit fuse board is made from thick glass fibre of good quality and is very robust. The connectors in the board for the cutout are also robust. This I should think is intentional because RR want you to remove the cutout. In the ambient temperatures you are running the car in this system has lots in reserve. A daft question. Is the temp gauge you are using accurate. Again the engine is a credit to its owner this is what I mean about keeping it nice. I love the colour. The corniche looks good in this colour. See how the black bits contrast with the silver bits. It looks so correct. best ignore the screen wash bottle though. I think RR forgot and got kits from Halfords. However the left hand front wing behind the front wheel has space for decent size bottle. I would mount the pump inside the engine compartment for ease of access.} (Message approved by david_gore) | ||
| Christian S. Hansen New User Username: enquiring_mind Post Number: 6 Registered: 4-2015 |
Bob... By temperature gauge, do you mean the hand held IR heat gun, or the engine coolant temperature gauge? While it is not unusual to find things broken or non operative even when new right out of the box, the use of three different hand guns seem to confirm that the coolant temperatures measured at the bypass elbow from the thermostat housing and all along the top of the radiator as well as elsewhere are running at the indicated hot temps. I thusly assume or conclude that both the sending unit and dash gauge are correctly indicating the hot condition. I suppose that assuming is wrought with possible error and the only way to tell for sure would be to replace the sending unit, but given the indicated temperatures as measured with the heat guns, it seems rather unlikely, and but for its inconvenient placement on the early Shadows I would have done so already despite not seeming to be a likely cause of the problem. As to the thermostat being new from Crewe, yet still defective and not fully opening, I observed marks on the bottom plate which when in the full open position contacts and shuts the flow to the bypass, of the exact same shape as the bypass orifice mouth, which indicated to me that it is both fully opening as well as firmly contacting the top of that bypass exit orifice. One test that has been suggested is to physically plug the bypass orifice, remove the thermostat entirely, reassemble, drive, and see what happens in terms of temperature. In time I will do that. As to the function of the fan clutch, while I have not performed your hammer handle variant, all the other tests as previously noted seem to confirm proper operation, or at least substantially proper operation of the fan. Even you posited that at motorway speeds, it is the forward motion that supplies the flow of air and not the fan, even if operating at peak efficiency, thus we have yet to address the issue of why that flow of air does not reduce the coolant temp. In order to eliminate the fan from the discussion, I suppose that a replacement is in order and worst that can happen is as the sign at may auto parts counters advises, "If the part you purchased turns out to not be the part that solves the problem...you now have a spare!" | ||
| John Kilkenny Prolific User Username: john_kilkenny Post Number: 194 Registered: 6-2005 |
Christian, A useful device for checking the operation of the cooling system is a laser infra red thermometer. These are available for around $30 and up and enable the temperature measurement at different points of the system. Start the engine from cold. Initially the thermostat will restrict the coolant flow to the block. When the coolant reaches the thermostat operating temperature the coolant will be pumped through the radiator and this can be confirmed by feeling the large top radiator hose, which will become warm. After a few minutes the coolant temperature should stabilise and the system effectiveness can be checked by measuring the temperature at the top and bottom radiator tanks (Not the Header Tank) The top tank will be around 85 to 90 degrees C depending on the outside temperature. The difference between the two tanks should be 35 - 45 degrees C for a good radiator and thermostat. John | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1292 Registered: 6-2009 |
Christian, Your observations regarding the thermostat's bypass closing disc having a mark matching the bypass oriface are both correct (as in those had to be obtained from it repeatedly hitting and "seating" there) and incorrect (it could easily be "was" not "is"). If you get to the stage where you remove the thermostat to do your "plugged bypass" test it's a simple matter to check whether the thermostat is opening and extending the disc sufficiently. I know you've seen me refer to the article, Thermostat Issues and Selection. Don Elliott does an excellent job documenting the actual amount of opening that's necessary to close the bypass and how to do the "boil test" on the stove to make sure your thermostat is actually doing that in practice. Brian | ||
| Christian S. Hansen New User Username: enquiring_mind Post Number: 7 Registered: 4-2015 |
John... Thank you for that. Yes, when I refer to an IR heat gun, I assume that to be the same tool that you refer to as a laser infra red thermometer. In this case there is no doubt that the thermostat is opening as I have confirmed that numerous ways including the sight glass technique referred to earlier in this thread, as well as the basic "touch" method, as well as the temperature monitoring method you note. I can monitor the temperature, typically at the bypass elbow as the coolant warms. Once the bypass gets to 185F or so, the thermostat opens and the temp of the upper area of the radiator begins to warm up indicating that the thermostat is opening and increasingly hot water is circulating to the radiator. Eventually the total coolant volume circulating thru the engine to the radiator and back via the lower hose reaches 200-210F where it stabilizes and does not continue to rise. This temperature is observed at the bypass elbow/thermostat housing area as well as the upper area of and across the radiator. The rubber radiator hose shows a lower temmperature and I assume this to be an anomoly given that it does not conduct heat in the same manner as the metal components. The radiator fan is spinning confidently and I can feel a significant amount of air being drawn thru the radiator matrix. The fan blades are NOT just simply and lazily turning, or windmilling as Bob described. If I then drive at motorway speeds, i.e.60-70mph, the airflow created down NOT cause the temperature to fall back down at all, let alone back to anything resembling normal, which I assume to be 185-190F. Since the radiator is just replaced new, heavy duty i.e. more tubes per inch and dimpled tubes, whatever that is, not a reconditioned old core, which here is the good 'ole US of A runs in at $1000 plus installation, and the travel speeds noted should/allegedly provide sufficient air flow for what has been described as a robust almost to the point of overkill coolant system and ambient operating temperatures are in the range of 60-70F, my conclusion (right or wrong) is that neither the radiator, nor airflow, whether provided by the fan or by travel speed, are the cause of the problem. My fall back position is that the VOLUME of coolant flow that is the conduit that carries hot water to the radiator for cooling is the culprit and if there is insufficient volume going TO the radiator, then irrespective of the quality of the radiator or the amount of airflow, there is insufficient cooler water returning to the engine necessary to exceed the capacity of the running engine to create heat, and the system tends to find its balance equilibriuim (heat created by engine, less heat dissipated by coolant flowing to radiator and back, and resultant operating temperature) at the 200-210F range. Somehow I sense that I am repeating myself, but my interest has turned from the radiator and airflow to the cause of the limited volume of coolant circulating thru the system, which would be a plausible explanation of why the airflow does not serve to reduce the temperature. Seems to me I recall an Australian member (but his name escapes me) some years ago who in the RROC-US forum reported an overheating problem on a Phantom II and while the discussion was mostly about the water pump, my advice was to do various flow tests to be sure that there was adequate flow and not an obstruction somewhere. The simple result turned out to be that there was a crumpled up gasket lodged in the lower outlet flange of the radiator and once removed, the flow was restored, and the problem was cured. With that in mind, somehow I just cannot let go of the possibility that something similar is happening here in this engine that is restricting the flow of coolant, not thru the radiator, but thru the block. Unfortunately the MPW has been put away while I enjoy and fuss with an EPW Silver Dawn, and since I have room for but one vehicle at home at a time, these follow up tests will have to wait. Rest assured, I will report back. Please pass along any other ideas, if any can be brainstormed. Thank you, all. | ||
| Christian S. Hansen New User Username: enquiring_mind Post Number: 8 Registered: 4-2015 |
Brian... Hmmm. Yes, I had not considered the "was, but not is" possiblity and that is why two heads are better than one when considering a problem. I did do the pan test and although opening began at 185F and when open at higher temperature was fully open and to the limit of the mechanism, that still does not mean that in operational conditions it is opening sufficiently to completely close the bypass for unknown reasons. I am looking forward to doing more tests, one of which will be a "engine block flow test" and the other the "thermostat removed and bypass plugged test". Hopefully one, the other, or both will shed some new light on the circumstances. Thanks for the caution and possible error in making the assumption that the thermostat is not part of the problem. | ||
| Bob Unregistered guest Posted From: 92.40.249.85 |
I have just looked at tee pne topics 61 and it has a diagram of the cooling system . nothing out of the ordinary. Please note about the bypass must be shut when stat is open. I have re read the postings quickly and its important that the dash gauge is not rely upon until checked. Maplins do a lazer type for £20. It goes from 0 to 350c. If the gauge is reading high then a resistor in series with the sender will lower the reading. It is also possible that the voltage stablizer is incorrect volts. Do the other guages show true reading. Fuel and oil pressure. If the gauge is reading 212f when is actually 190f this is about 10%. Stabiliser are about 9v so if faulty 10v will raise the gsuge by 20f. The stablizer is behind the dash. Is about 1" square 1/2" deep with an adjuster locked with a blob of glue. This is a general purpose Joe Lucas part and is available from lucas. Beaware of cheap ones that are not lucas. Reports of bad electrical equipment abound. If the stabilzer is OK. Then a resistor will be required. This is two resistors in series. One end is connected to the sender and the other end of the two resistors is connected to earth. Gauge is connected betwèn the resistors. Because the error is 10% then the resistor connected to the sender is 10% of the other resistor. Say 10k for first resistor and 100k for the resistor that goes to earth. This is called a voltage divider. Or fit a potentiometer. A pot will have 3 connections one outside to the sender the other outer to earth. The centre connections is the moving contact and goes to gauge. By adjusting the pot the gauge can be calibrated so that when its 90c it os 90c the rest of the scale will be out but it doesn't matter because overhaeting is whats important. 100k pot. The pot is 1/2 dia and a quid. The reason for high resistance is that amps are milliamps only. If I were to use 1ohm and 10 ohms I still have the same ratio but I have 11 ohms connected to earth. The voltage divider must have more resistance than the sender. There is voltage divider calicator on the web which will give the best values to use. A pot is like a voltage divider that is adjustable. Gauges that are lower are a problem however because the bezel is hidden behind the wood the bezel can be prized off so that the innards can interfered with usually by bending something. Works every time. My dad used to work for Sperry, who made avionics. Bending stuff in instruments to calibrate was common. A good example is petrol tank float arms by bending the gauge can set to show empty if is a gauge that shows empty when it isnt or the other way round shows just off empty when it is empty. Agian just one part of the scale is important the empty bit. (Message approved by david_gore) | ||
| Christian S. Hansen New User Username: enquiring_mind Post Number: 9 Registered: 4-2015 |
Bob... Thanks for the info on adjustments if found to be necessary. While the gauge reads just a bit under HOT, that has been confirmed as an accurate assessment of the temperature via the use of not less than three different professional quality IR heat temp guns, my own, and those of the local RR facility. All confirm the running temp with the original core at 220F, and with the installation of a new core at 210F, so while the new core did serve to improve the situation, presumably due to better flow and thus efficiency, that was not the main source of the problem, just an accessory coincidental contributor. The main source is still presumably elsewhere and stil unknown. Next time the MPW is "out and about" I will run it by another shop to see how their IR temp reads, but do not expect any surprises. There is relatively certain cause to accept that the running temp REALLY is as indicated on the gauge and as confirmed by the hand held IR heat guns. I wish it weren't so, but the evidence is rather overwhelming that there is yet a problem. More tests are clearly needed. I will report back, although I am swamped at work and fussing with my special cars has to come out of spare time. The EPW Dawn gives me my daily RR driving "fix" and the MPW problem will still be there when I get back to it. Life is too short to drive a boring car!! I sometimes split my grocery list into two pieces and go to two separate stores, just so that I will have twice as much time in my "pride and joys". Doesn't everyone do that?? | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1293 Registered: 6-2009 |
Christian, From what you've described so far I expect the thermostat is working, but, you have to make sure that it opens to its fullest extent around 190-ish degrees F. If it's somehow starting to open at 185 but is "taking forever" to reach full open that could cause a problem. You won't have correct flow through the radiator unless the bypass cutoff disc has extended far enough to close it off at the appropriate temperature. Your problem is interesting because there really are a limited number of variables involved but, upon occasion, that still doesn't appear to make the solution any easier. Any unexpected factor(s) you might discover (such as the gasket issue with the P-III you described) simply adds to the database of possibilities for the next person who faces this and finds it isn't one of "the typical suspects." Brian | ||
| bob uk Unregistered guest Posted From: 188.29.164.118 |
I note the independent temp gauges so the car is definitely running hot. Was this car owned by Peter Sellers. The by pass. If the by pass is still open when the stat is open then this could be the problem. I wonder if the stat was removed and the by pass plugged what the temp would be. Best to warm engine with stat installed first. I would first measure from stat opening to by pass then operate the stat and measure it to see if actually goes far enough. Note this car has a water tap does turning on the heater pull the temp down due to cold water from the hesyer matrix. It should do. My car drops by 5c and then qickly stabilises due to main stat closing a bit. It's a check I do with my car often.. Because I am wary of overheating my engine. Not quite paranoid just wary. I understand your concern. (Message approved by david_gore) | ||
| John Kilkenny Prolific User Username: john_kilkenny Post Number: 196 Registered: 6-2005 |
Christian, As your engine is similar to mine I thought I would check some parameters of my cooling system. I have fairly recently fitted a new radiator core and a new RR thermostat. The radiator fan is the standard fixed type. The cooling fluid is 50/50 Standard Ethylene Glycol Antifreeze and water. Today's ambient temperature (Melbourne) is 20 degrees C (68 F) I made a 20 minute trip at speeds of between 60 and 80 kph (37 and 50 mph). Immediately on returning home I took measurements with an infra red thermometer as in the diagram. The top tank was at 88 degrees C (190 F) and the bottom engine inlet at 64 degrees C (148 F). The temperature gauge was slightly to the left of the white dots pair. Leaving the engine idling for around 12 minutes (630 rpm) I took the measurements again. This time the top tank was at 84 C (183 F) and the engine inlet at 52 C (125 F) and the temperature gauge had dropped slightly to about one quarter into the white band. The increased difference in the second pair of readings is caused by the thermostat restricting the coolant flow which keeps the coolant in the radiator longer. But because the pumped volume is lower the engine temperature is maintained. The thermostat is doing its job. You may like to take these measurements on your car. John  | ||
| Christian S. Hansen Experienced User Username: enquiring_mind Post Number: 11 Registered: 4-2015 |
John... THANK YOU!!! You have just confirmed my suspicion as to the ideal running temperature and the indicated position of the needle on the dash gauge, but which unfortuntately also confirms that I indeed do have a problem somewhere. Now the hard part of figuring out the source of the problem continues. I tired of the stress of driving an suspectedly running hot engine and have put the MPW away for now, in preference for an EPW Silver Dawn (you don't really appreciate power assisted steering until you no longer have it), but will return to the MPW issues in due time. I am so very appreciative of your efforts and time invested in verifying these data points on your engine. Christian |
