| Author | Message | ||
     Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 210 Registered: 4-2015 |
Re: 1979 Shadow II Chassis# SRK37338 "Today's Problem"... Cutting to the chase...the horizontal seam on the top tank has burst, spilling hot antifreeze and steam all throughout the engine bay and completely saturating the underbonnet padding. Antifreeze was also seeping out from the steam valve gasket seam. Great. I could at least drive the car with the broken seat sdjustment switch. Not so with this problem. Question is: Will the Shadow engine overheat simply due to the crack not allowing pressure to build up? I was under the impression that a pressurized coolant system was simply so the system could run at a higher temperature, not that it would overheat in the absence of that pressure. Auxilliary queation is therefore, is pressure NECCESSARY for the engine to not overheat? Unlike my MPW coupe from a thread a year or so ago, which would run hot even under pressure for reasons never determined, in this case, even though steam and hot fluid were gushing out of the split seam with the attendant sounds of boiling fluid, the temperature gauge barely showed into the white band. Perhaps a bit higher than before the overheating, but not significantly. Clearly the fluid was super heated, and I am now wondering if the temperature gauge is not working properly either? Under the circumstances, I would have thought the temp gauge would have been pinned at "hot". Any thoughts? I need to rummage around in the boot of the MPW and find that infrared heat gun I was using. Yes, honeymoon over! | ||
| Omar M. Shams Grand Master Username: omar Post Number: 664 Registered: 4-2009 |
Dear Christian, From what you have described it is probable that the temperature sender unit that the previous owner has installed is not the correct one. There are many generic temperature sender units that will fit in the engine but they may not have the same temperature range. This means your temperature gauge will never show accurately (if indeed the wrong sender unit has been installed). I would be inclined to replace the sender unit with a known RR Bentley part and then see what the gauge reads. I would also replace the header tank with one from a car being broken on ebay. Good luck Omar | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1931 Registered: 6-2009 |
Well, given the amount of boiling you describe the first thing I'd suspect is that you have far, far less than the prescribed 50/50 mix of antifreeze and water. I can't remember what the unpressurized boiling point of that mix is at the moment, but I believe it was higher than the maximum temperatures that I ever got as a reading at the thermostat housing. That kind of boiling, if the temperature sender is not faulty, just screams way too much water and way too little antifreeze. You may actually be overheating, but it takes a lot to get 50/50 to "rolling boil" stage. No matter what, I'd check that out along with everything else. Also, if you decide to drain the cooling system, I find the hose removal at the bottom of the radiator to be a grand PITA. I found it far easier to remove the entire drain valve with a wrench where it screws in to the radiator. The resulting flow is way faster than through the drain valve itself and much easier to control and catch. Brian | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1265 Registered: 5-2012 |
Christian is pressure NECCESSARY for the engine to not overheat? No. The boiling point of coolant at 50/50 mix is about 225F. My car runs at 205F and on hot days like today (ambient 92F) it creeps up to 210F, well below the BP of coolant at 50/50. In theory it could run at atmospheric pressure. I have to stress I'm speaking hypothetically here. In practice most cars run at 15psi which elevates the BP of the coolant to around 250F, which is desirable to allow for overheat conditions. In my view, the reason your car overheated is because the coolant was spraying out through the split in the header tank and the coolant level got progressively lower causing the temperature increase. I guess the real question here is did your car overheat to such an extent the seam of the header tank was ruptured. I would doubt this as I would expect a hose to blow well before the tank was split by internal pressure. Geoff | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1546 Registered: 6-2006 |
Remember that it is not the temperature of the coolant flowing around that makes it boil, it's where the coolant touches a too hot part of the engine. In hot soak situations you need a pressurised cooling system. Like a kettle, it's not the top of the water that boils it's next to the elements. The steam valve should open before the tank splits. The tank can be us soldered. The steam valve boss resold red then the top and bottom resoldreed . Check for causes of overheating first. | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 213 Registered: 4-2015 |
Brian, Omar, and Geoff... Thanks for your input and ideas. I am still in the diagnostic phase, trying to figure out what is happening, or what caused it to happen. After everything cooled off and I hosed the engine compartment down to rinse away that nasty antifreeze as best I could, it took almost two gallons to top up the system. In retrospect, I do not believe that the pressure of the overheating fluid caused the seam to burst. I think that it was a latent condition that I "purchased" with the car which was lying dormant waiting for an unsuspecting new owner to take possession. (Is my paranoia showing? Is the car is "out to get" me?) In the cool of the evening I just took the six mile round trip into town to grocery store without incident. Upon return, it was however evident that fluid was leaking under small amount of pressure from the seam. Not steaming or overheating, just seeping. Over time that cumulative loss will of course eventually deplete the system in a vicious spiral until it overheats again. It is strange however that I did not notice any smell of hot antifreeze, or dripping onto the ground during the prior "shake down" trips, especially considering that I was specifically looking for just those signs. When the event happened, I had left the car idling with the AC climate control system "on" but for really no more than 10 minutes or so while arranging things in the garage. When I came back to the car, the pool of lime green fluid flowing away from the front of the car alerted me and upon opening the bonnet, the problem was evident...spraying fluid and steam everywhere. While one might say to not leave a car idling, that was really no worse than getting caught in a traffic jam during summer heat and any properly operating system should be able to idle indefinately..or at least most every other car I have ever had did so and I would expect no less here (the MPW coupe aside!). Ambient temperature was barely in the low 80s F, so it was not even a hot day. Anyway obviously the top tank needs repair and engine temperature monitored with a heat gun. I suspect Omar is correct that the gauge is not reading properly or sending unit not proper as they both should have caught the condition and displayed it on the gauge. Omar...when you suggested a used one, is that because the seams are not readily repairable due to construction or other reasons? Brian...I will check the concentration to be sure it is 50/50 but from the looks of what came out, I would venture to say that it looked proper...lime green and not straight water. Of course I topped it up with straight water, so it is now more dilute that it was before! Geoff...I would believe that you are correct (and confirm my understanding) that the system should operate at atmospheric pressure without overheating and that the purpose of the 50/50 mix and the pressure is to allow the system to operate at higher temps without boiling when and if needed. Maybe someone else will be able to confirm whether the system (in the absence of losing fluid from the seam) needs to be pressurized in order to prevent overheating, that is, it WILL overheat at atmospheric pressure. Let's say you simply vented the top of the tank so that no pressure would develop, but no fluid would be lost either. Under those conditions, would the system overheat under normal conditions...i.e. 70F-80F...and while standing at idle...like in a traffic jam. My unpressurized '55 Silver Dawn will sit there at idle for an extended period without overheating, and I have had regular "Detroit made" camper vehicles that would idle all night long in summer humidity and heat with the air conditioner running and at only a slightly elevated RPM without incident, as well as in the winter idling all night long with the heater on. Is that too much to expect from a Shadow?? | ||
| Patrick Ryan Prolific User Username: patrick_r Post Number: 228 Registered: 4-2016 |
I think Geoff has hit the nail on the head. I've seen many times trucks overheat without the gauge showing an issue. Sender units need to be surrounded by coolant to deliver a reading, no coolant or steam will not deliver a reading. Our new age truck engines also have a sender unit in the lower part of the engine so they can still deliver a reading even as the coolant drains through a leak. Omar's suggestion of course is extremely valid, and before the car goes back on the road, the sender and gauge must be tested. | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1547 Registered: 6-2006 |
Remember that it is not the temperature of the coolant flowing around that makes it boil, it's where the coolant touches a too hot part of the engine. In hot soak situations you need a pressurised cooling system. Like a kettle, it's not the top of the water that boils it's next to the elements. The steam valve should open before the tank splits. The tank can be us soldered. The steam valve boss resold red then the top and bottom resoldreed . Check for causes of overheating first. | ||
| Omar M. Shams Grand Master Username: omar Post Number: 665 Registered: 4-2009 |
Dear Christian, my suggestion to replace the header tank was based on my own experience. I tried repairing my old tank and it was in and out of the car like a yoyo. My repairs were never effective - maybe because of the skill (or lack of) but in the end an ebay purchase cured the problem for good. The proposal to replace with a used item from someone parting out a car is based on the best value-for-money option. | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1548 Registered: 6-2006 |
If overheating on tick over check the viscous fan coupling. | ||
| Patrick Ryan Prolific User Username: patrick_r Post Number: 229 Registered: 4-2016 |
Chris, The continuing thread here is the air conditioning. Does the Shadow II have an electric fan, or a standard fan like the Shadow I? Of course this should be priority to test when the car is ready. Also, be sure to at least test the thermostat before the car is completed. Just some teething probs mate. | ||
| Jeff Young Prolific User Username: jeyjey Post Number: 254 Registered: 10-2010 |
Hi Christian, I had my T2 for years before the header tank seam started leaking. I noticed it before any overheating episodes, so they would appear to just fail on their own sometimes. If you're getting overheating while stationary, I'd check the viscous coupling on the fan. It also sounds like your coolant level warning circuit isn't working. There are some discrete components (diodes and transistors) in the coolant level amps that tend to fail with age, but they are easily repairable. (It could also be a loose or broken wire somewhere between the probe and the amp, or even a burned-out bulb in the warning light pod.) Cheers, Jeff. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1932 Registered: 6-2009 |
Several answers: 1. The two series cars use a conventional fan just like the series one cars did. It's a different style and has plastic blades (and way more of them. Here's a photo of what was left of mine after it hit the radiator and sliced a couple of tubes open.  2. My article on rebuilding the coolant level amplifier: UD19427 Rolls-Royce/Bentley Coolant Level Amplifier Repair 3. Not that Mr. Hansen will go this route, but there are both alternative viscous fan clutches and fan blade sets that can be fitted to the SY series cars. I know there's a post on these very forums showing an adapter ring that was machined to allow the SY2 fan blade set to mate with a very commonly available viscous fan clutch. 4. I'd replace the thermostat as a matter of course, and I would not use the OEM thermostat because of the well-known and often reported issues with both its lifespan and design. Thermostat Issues and Selection An observation: If the coolant level was as low as described it could very well have been so low as to not be reaching the temperature sender at all. It's pretty high up in the system on the lower part of the thermostat housing, if memory serves (I haven't run outside to look). As previously noted, unless it is surrounded by fluid it will not send any accurate readings to begin with. I am actually shocked that the steam valve didn't do its job before the header tank literally came apart at the seams. Brian | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 216 Registered: 4-2015 |
Brian... You are correct about the fan type...plastic and multiple blades as well as the steam valve. Wonder if it is jammed? First order of business is to remove and resolder the top tank, checking steam valve, and replacing steam valve gasket in process. Once the system is sealed up and can be pressurized, I will proceed with all the other facets...viscous coupling, thermostat, sending units, etc, as I try to analyze what works and what is not working as properly intended. One observation however is that there is an electric fan mounted to front of radiator which comes on immediately even when the car is cold in the morning. This is,m I presume, incorrect as that fan is a "back up" cooling device? Running all the time is the opposite of the concern David Tower had recently where his never seemed to come on. Debugging a newly acquired preowned car is the biggest hassle especially after relying on the prior dealer owner who claimed to have taken care of sorting everything out to proper specifications. I suppose that "everything" is rather vague. Anyway, one step at a time...top tank first. | ||
| Patrick Ryan Prolific User Username: patrick_r Post Number: 231 Registered: 4-2016 |
Chris, The fan does sound unusual. Does it come on all the time as you say with the A/C on? or even with it off? Also, Please check the direction of the fan when it is running. I have seen many electric fans wired backwards. | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 219 Registered: 4-2015 |
Patrick... It comes on when the ignition is turned to "run". If engine is started, it stays running since after start, the key is returned to "run". If it was running in reverse, I presume one could feel a draft flowing out the front of the radiator shell. That said, with engine off, but fan running, one can hardly feel any air flow thru the engine side of the matrix. Runs, but seems to be rather ineffective. Not sure if it is factory, or a cheap junk "feel good" aftermarket add-on. | ||
| Patrick Ryan Prolific User Username: patrick_r Post Number: 232 Registered: 4-2016 |
Chris, A common issue we have here in Australia is the gap between the condense & the radiator over time will fill up with dirt, dust, grass, twigs, anything at all you can imagine I have pulled out of this gap from different vehicles over the years. Now is a good time for you to go through your cooling system while the car is off the road. A good electric fan will pull air through the cooling array big time. So this is worth a look. Also another common issue is the fins of both the condenser & Radiator get clogged by the same crap as described above. An easy way to check this is to shine a torch through from the engine side, and you should get very good clear light shining through. However due to the age of the car and the issues, I would suggest removing the radiator and giving it a good reverse blow through (from the engine side out) onto an old sheet or something to collect the debris. You will be shocked at what you find. Do the same with the condenser while still connected so not to lose you gas. You will be amazed at what you will get out of it. Lastly, Also with the radiator out, be sure to check that the cooling fins are all in place, not rotted or corroded or flattened out thus not allowing any air to pass through. if they are flattened or damaged you can purchase a fin comb to fix them before re instillation. Here is an example.  | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 220 Registered: 4-2015 |
Now that's a cool tool. Certainly beats pulling a dull table knife or flat screwdriver down each individual gap! Have in the past tried both. Neither was satisfactory! P.S. I prefer "Christian". On the other hand, in my business, if a customer is wanting to spend money, I say, "Call me anything you want. Just call me!" Thanks! | ||
| Patrick Ryan Prolific User Username: patrick_r Post Number: 234 Registered: 4-2016 |
Sorry Christian, I have a life long friend called Christian, who since the age of 8 have called him Chris. Just habit, sorry about that. | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 221 Registered: 4-2015 |
Patrick...No offense meant. All is well. You have to disclose your preferences, otherwise how would anyone know? I was just reading the manual on the seat adjuster problem. Finally found the data in Electrical section. Seems to confirm that the switch is the fault. Top tank takes priority though. Thanks for your help and observations with all my questions! | ||
| Patrick Ryan Prolific User Username: patrick_r Post Number: 235 Registered: 4-2016 |
That's Ok Christian. And I do understand what you are saying about preferences. You were right all along regarding the switch. Yes the cooling system is number one priority at the moment. Keep us posted as to what you find. I would be very interested to see if the cooling fins are clogged by doing the torch/light test. | ||
| gordon le feuvre Prolific User Username: triumph Post Number: 116 Registered: 7-2012 |
Christian, 1. Did you check thermostat as these cars are fitted with "failsafe" which melts capsules in top face of thermostat if car has really overheated i.e thermostat not opening. These holes will then still allow coolant to circulate. 2. As Paul says once coolant has left thermo.housing the gauge does not register coolant temp. 3. Cars from around '74/75 all had high metal temp buzzers fitted into rear of head on 'A' bank as coolant could leak out of heater hoses and starve rear of heads of coolant. did this go off? my experience is it is not that uncommom for header tanks to split. have seen for before. It does not definitely mean there is an underlying problem. The can be resoldered, but take it to someone who hows how to solder with experience. it is SO easy just to drop solder into grouve between top and bottom halves that then looks like it's working only to be sitting on metal surface. Bit like gobby welding! I would have tank repaired/replaced, check thermostat, top up coolant correctly. Run and see before looking for underlying issues. Just had Cloud 111 that I chased my tail on with heat gun readings etc that in e3nd really did not mean much. decided to follow my own advice, car was the happy being driven as normal car, with no overheating. | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 222 Registered: 4-2015 |
Gordon...Thanks for the input. Yes, before I start chasing ghosts, I will remove and have top tank properly resoldered, renew the steam valve o-ring and gasket, pressure test to verify that the steam valve opens, and if passes, reinstall. While it is out, will also check thermostat. I have not yet determined where the temperature sending unit is on my chassis. I am however concerned that the either the sender or the gauge is not reading correctly and that the high temperature was not indicated. Paul is a pro, for sure, but I am not grasping "once coolant has left thermostat housing the gauge does not register coolant temperature." Could you please reword? I assume he is assuming that the sending unit is in the thermostat housing and can, of course, only read the temperature of the coolant at that point. Irrespective of the location of the sending unit, logically it will only indicate the temperature at that point and nowhere else. Also, I appreciate that if there is no coolant at the point of the sending unit, there will be no reading since the probe needs to be immersed in coolant. There was no buzzer so either it did not trigger, is not on my engine, or is not operating properly. For now, I'm just going to concentrate on getting things back in order before doing any further testing of other possibilities despite haveing been considerably rattled by the episode. I think that it seemed worse that it was because antifreeze was being ejected from the split under pressure and steaming all over the hot engine and being blown around by the turbulance generated by the fan. I had left the engine running as I hosed everything down (staying away from the exhaust manifolds, spark plugs and distributor), as I had heard that it was not good to shut off an overheating engine and better to hose the radiator down enough to get the filler cap off and then refill with engine still running. Something about cold water hitting hot internal parts of the engine. Not sure if that story has merit, but that is what I did. Took a few moments to get things cool enough to get the filler cap off without it blowing hot fluid all over. If I cracked it a turn or two, more hot fluid was ejected by the pressure, so left it loose as I hosed things down. Once pressure subsided, removed the rest of the way and added water from the hose. Finally turned the engine off once the commotion died dwn and then hosed the antifreeze off everything. Unfortunately it does not realy hose off very well and leaves a film. Not sure what to do about that as it is all over at least the front half of the engine bay and completely saturating the under bonnet pads. What a mess! | ||
| gordon le feuvre Prolific User Username: triumph Post Number: 117 Registered: 7-2012 |
Your shadow 11 has high metal temp sensor( they were fitted from '72 facelift) if you look at no 4 spark plug on "a" bank it is the electcrical above spark plug, if you remove connector and earth it on cylinder head it should activate buzzer under dash. It does not work putting cold water into hot engine as this just turns to vapor. Just take time to let engine cool down, then refill. Run and let cool overnight, as it does take this time to recheck and top up. Obviously, this is not a luxury afforded to problems at side of road. | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 226 Registered: 4-2015 |
Gordon...I will do that and if the buzzer comes on as it should, that would indicate that my "event" did not generate sufficiently hot temps at that location to trigger the buzzer, which would be good to know as at this point as I am not sure just how hot the engine got. It did not seem to be "cooking" and radiating excessive heat as I was hosing things down, nor after I finished. I am suspecting that the whole mess was simply the crack in the seam allowing fluid to jet out and create a visual mess. As an aside...and I have not mentionned this yet...prior to this "event", the left side hydraulic pump on the engine seemed to be unusually noisy, to the point that two people, one neighbor, and one stranger at a gas station, who came over while I had the hood open, both immediately noted "valve tappets?". The noise is of course the pumps, not the tappets, and I did not engage in conversation on the topic. AFTER this heating "event" however...for whatever reason...that tapping noise has completely disappeared. The sucking sound of the air pump is now the most noticeable noise in the engine compartment. Is this absence of tapping good or bad? Has something changed the clearances on the pump tappets of shafts or whatever such that the noise has gone away? With valve tappets, having no noise could actually be bad as it means the clearance is too tight and valves will burn as a result. Am I too paranoid? (David Tower...can I join your club?) | ||
| Bob Reynolds Grand Master Username: bobreynolds Post Number: 399 Registered: 8-2012 |
"I had heard that it was not good to shut off an overheating engine and better to hose the radiator down enough to get the filler cap off and then refill with engine still running." Well, that's certainly the first time I've heard that one! That sounds very dangerous to me. Surely it's better to remove the source of heat (ie switch it off) as soon as possible, open the bonnet and leave it for an hour or so. | ||
| John Grieve Experienced User Username: john116 Post Number: 39 Registered: 4-2012 |
Agree, every car owners manual I have ever read always says to turn off the engine immediately. Even a few seconds delay depending on what temperature it's reached could be catastrophic to the engine. | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 227 Registered: 4-2015 |
Bob and John...Yes, I suppose I misinterpreted. Certainly in a catastrophic loss of coolant, such as a burst radiator hose where the coolant is dumped out and the engine rapidly runs dry, shutting the engine down asap is obligatory. In this case, the problem was a seam crack near the top of the system so fluid was only slowly being ejected by the pressure, but with much fanfare! I suppose the advice I was thinking of was to not try to remove the filler cap until the pressure has been released, and the best way to do that is to hose the radiator top and core down enough to get the cap off without creating a geyser, and considering that water that does not boil under pressure boils rapidly when the cap is removed too quickly and pressure reduced, that is what causes the geyser and scalded bodies. | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 229 Registered: 4-2015 |
More on the top tank issue: Yes, I am often accused of trying to "overthink" things...and here I go again... Prior to just removing the top tank and getting it repaired, I was hoping to find my infrared heat gun and take some readings. Meanwhile, I have run a few experiments that have to do with the issue of whether the Shadow cooling system will run at atmospheric pressure. The reason I ask is that in a thread last year where I was having a "running hot, or not?" issue with my '68 MPW Shadow Coupe, I beleive the consensus was that under "ordinary" climate circumstances...not Dubai, or Singapore!...and given that the thermostat opens at about 190F...that temperature is about where the system runs...increasing to 210-220F or more under hotter climate conditions. Also, that the purpose of a pressurized system is to allow for those hotter coolant temperatures without the coolant boiling and being depleted. What I am trying to determine is whether under those "ordinary" circumstances where the coolant is running at 200F or less, theoretically the coolant will not be boiling anyway, and therefore the need for pressure is superfluous. So...the question is: Why should the system NOT operate properly WITHOUT pressure under conditions where the coolant does not exceed 200F? Where I live in San Francisco, the climate is very "ordinary" and temperatures under which I operate are typically in 60-70F range and I therefore assume that the coolant in a properly operating system will never boil anyway, even without a pressurized system. Correct, or not correct? What I have found with the current issue...cracked seam in top tank...is that when the system builds up pressure, as it is designed to do...that pressure forces the coolant out of the cracked seam. So, I wondered, what would happen if I prevented the system from pressurizing? Would that also prevent the coolant from being ejected? What I found was that if I topped up the coolant to bottom of filler orifice and left the filler cap cracked open a few turns to allow pressure to escape, rather than build up, after only a few miles the temperature would rise and coolant would be ejected thru the steam valve, out the overlow line, and onto the ground, but nothing is ejected thru the cracked seam. This makes me wonder if the steam valve is stuck open and thereby allowing the fluid to be pushed out. On the other hand, if I repeat the experiment, top up the fluid as before, but tighten down the filler cap, what happens is that after a few miles, the temperature builds up as before, but instead of the fluid be ejected thru the steam valve and overflow line, this time, it is ejected thru the cracked seam! Very strange. So the question is: What is it that is causing the fluid to be ejected thru two different places depending on the status of the filler cap...open or closed?? Any ideas? Of course the real problem is why the fluid is heating up in the first place. Possibly stuck thermostat? Tomorrow or the next day, I will remove the top tank for repairs and then remove and check the thermostat for proper operation. The question for today was simply the "why" for the different circumstances of where the fluid exits the system, based on the status of the filler cap. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1271 Registered: 5-2012 |
Hi Christian I think the key to all this is what Paul Yorke said earlier in this thread re: kettle effect. As Paul points out, bubbles form around the element of a kettle well below boiling point. In the engine the kettle elements are the cylinder liners. Bubbles forming around the liners are highly undesirable as they reduce the cooling effect of the water. Also, the temperature around the liners is going to be much higher than at the top tank, leading to pressures that will eject the coolant through the split in your header tank, even though the temperature measured at the tank and even the thermostat housing (where the sender is located) can be well below boiling point. It does sound like your steam valve is faulty. One would expect the coolant to always be ejected through the split seam as the coolant pressure builds up. I think your plan to check the thermostat is a good one. Also, as Paul recommends, check the viscous coupling on the fan. As a rough guide, when the engine is turned off the fan blades should stop quickly. If the blades rotate for more than a single revolution then the coupling needs replacing. This is a difficult judgement to make if you have not seen how the fan should behave. After I replaced the coupling on my car the deceleration of the fan blades was very marked. You could see they were being pulled up very quickly. The other point is the viscous coupling operates at different temperatures. On a cold engine it is on for a minute or so. Then as the engine heats up it "switches off" i.e. fan blade rotates freely and then when the engine gets hot the coupling "switches on" again. Best test is from cold. Geoff | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 1025 Registered: 9-2004 |
If I had this problem I would first check the thermostat, if ok I would do a Cylinder leakage test to make sure the head gaskets etc are ok. If ok check the flow through the rad it may be blocked causeing excess heat that goes to the highest point steam valve header tank. As you state the electric fan running all the time fault should not let the engine at idle run hot.Guessing with cooling faults with this and that can be a costly excersize. | ||
| Jonas TRACHSEL Frequent User Username: jonas_trachsel Post Number: 90 Registered: 2-2005 |
I think that the steam you had in the engine compartment was not from the engine overheating/boiling, but rather from the cooling fluid sprayed from the ruptured tank seam over hot engine parts such as the exhaust. This theory would give you the hope that your engine suffered no damage. | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 231 Registered: 4-2015 |
Precisely, but the question remains as to why the engine runs so hot in the first place. Engines that run at 185F to 200F, as many others have reported theirs run at, should not boil even if the system is not under pressure, as the purpose of the pressure is to raise the boiling point so that under circumstances where the coolant temperature runs hotter and exceeds the normal boiling point of water (210F), say driving up a mountain pass duting the summer, or stuck in stop and go traffic during hot weather, etc, so that the fluid does not boil and be lost that way. Correct me if I am wrong, but on a system that is running at below 200F, as it would under ordinary circumstances, there should be no boiling and the system could run with the cap off and thus no pressure, without boiling. Yes? No? | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 232 Registered: 4-2015 |
Clarification...as to the purpose of a pressurized system...I assume that it is to increase the boiling point of the coolant, not to affect the operating temperature. That is, a pressurized system does not reduce the operating temperature, but simply raises the boiling point of the coolant allowing it to run hotter without boiling. Yes? No? | ||
| David Gore Moderator Username: david_gore Post Number: 2069 Registered: 4-2003 |
Christian - the answer to your comment is a resounding YES. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1276 Registered: 5-2012 |
Christian When owners report their cars are running at 185-200F their engines are actually running at close to or even above boiling point. This is because coolant temperatures in an engine are not uniform. The 185-200F quoted is almost always taken from the thermostat housing, where the sender unit is located. The temperature at the cylinder liners is much higher than this. On my car, where the sender unit is located, close to the cylinder liners, the temp range is 205-210. I understand what you are saying. In theory, if the radiator and header tank were of sufficient capacity the pressure of the hot coolant coming from the engine could be overcome by the sheer volume of coolant and the system run with the cap off. However these engines are designed to run under pressure, so leaving the cap off will cause the coolant to be forced out and the coolant level reduced until such point the entire system is at boiling point. Re: a pressurized system does not reduce the operating temperature, but simply raises the boiling point of the coolant allowing it to run hotter without boiling. Yes? No? No. This is because as the engine coolant heats up, dissolved air bubbles out and collects around the hot spots of the engine and particularly around the cylinder liners. This air acts as an insulator so the cooling effect is less. The coolant in fact runs cooler but the engine parts run hotter. A highly undesirable state of affairs. So running the cooling system under pressure compresses these air bubbles and allows closer contact of the coolant to the metal parts of the engine, taking the heat away more efficiently. So a pressurized system does reduce the operating temperature of the cylinder liners (but not the coolant). Geoff | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1277 Registered: 5-2012 |
David I note we answered at the same time, but with different answers. I agree with you the physics is such that as pressure is increased the boiling point increases. But in the complex environment that is the cooling galleries of an IC engine the operating temperature is affected by pressure. I guess if the average temperature between the coolant and internal parts of the engine is taken, there is no overall change in operational temperature, but I am trying to point out how important it is to run a pressurized system. Again, we are not dealing with a homologous system here. Geoff | ||
| Patrick Ryan Prolific User Username: patrick_r Post Number: 244 Registered: 4-2016 |
This is great reading gents. We are all learning something from Christians unfortunate event. However the science behind the coolant and a pressurised system is sound, I am 100% confident that his issue lays in the lack of heat exchange through the coolant to air system. I assume Christian, you had the overheating issue before the tank ruptured? Christian, Please be sure to carry out every suggestion I and others have made before putting your car back on the road. My suggestions about contaminated and blocked cooling fins in the rad, and the condenser are sound. I have seen countless cars and trucks overheat due to this. All it takes is 10 minutes with a good hose or air blower to clear, and a good light source to check every square cm of the rad and condenser form behind when done. The electric thermo fan is definitely suspect, and of course the viscous fan needs to be checked as mentioned. | ||
| David Gore Moderator Username: david_gore Post Number: 2071 Registered: 4-2003 |
Geoff, In my experience and provided the cooling system internal passages are clear of scale and hard encrustations, the only time localised overheating will occur is if the flow of coolant through the system is retarded sufficiently to allow localised boiling. The normal flow rate from a water pump in good condition is more than adequate for preventing localised boiling. In fact from my memory of momentum,heat and mass transfer dynamics taught during my academic training, the most efficient heat transfer occurs under turbulent flow conditions engendered by high flow rates conversely low fluid flow rates result in laminar flow conditions which result in much lower heat transfer rates. In summary, what this means is the "boiling" raised by Christian may have been the result of reduced coolant flow rates through the engine block caused by loss of coolant through the leak and not an inherent fault in the system itself. | ||
| ross kowalski Experienced User Username: cdfpw Post Number: 28 Registered: 11-2015 |
I did a little IR research today. Today was 85F ~ 100F I was driving the car around all day no overheating. ------------------------------ I checked he temp of the kitchen 71F sounds plasable with the air conditioner on.  ------------------------------ Boiled some water and it was two hundred something which is plausable.  ------------------------------ The car was cold.  ------------------------------ I drove 25 miles to start a Ford Powerstroke diesel I am buying. The temp gauge indicated in the white band, but to the left of center a bit.  ------------------------------ I checked the filler neck and it read 161F on the filler neck which is plausible. The car seems to run cold. I used a thermostat that didn't really fit so maybe it lets coolant around the edges???  ------------------------------ I drove another 25 miles on the freeway down to the local Walmart and back to grab some oil to put in the diesel and on the way down the gauge indicated operating temp. ------------------------------  ------------------------------ I checked the thermostat housing and it read 174F which is plausible.  ------------------------------ I didn't take any more pictures mostly because I was busy, but I just drove the 20 miles home and the temp is 97F and the car just sat at operating temp. I can say for sure that the system has plenty of capacity for keeping a 6.75 engine cool. My Lotus... , idle for 30 seconds on a hot day and the temp gauge starts climbing. Hmmmm. | ||
| ross kowalski Experienced User Username: cdfpw Post Number: 29 Registered: 11-2015 |
Christian, If the car were sitting in my driveway, I would do the following in the following order... 0. Drive the car and check it with my temp gauge and see if it is really overheating. The same IR gauge on a working and suspect car would answer that. I have an in-hose sensor on the Lotus so I might also put that inline with the upper hose. Bottom line, I would make sure the car is really running too hot. 1. Feel the upper radiator hose at operating temp. If it is rock hard, bad head gasket. 2. Rent/buy a head gasket check kit from PepBoys - Advance Auto - Whitlock, what have you, and see if the cylinder head gasket has failed. If the solution turns purple, it is a bad head gasket or cracked block/head. 3. Pull the lower radiator hose and look in the block and radiator for sediment with my internet endoscope (the best $10 for really knowing what is going on inside an engine). If it is full of sediment, which it likely won't be, clean it out. 4. Look through the radiator and condenser cores. If you cannot see light from a flashlight, hose them off or pressure wash them off. 5. Run water through the radiator with a hose from the top to bottom with my hand over the bottom fitting. After the radiator was full, shut off the hose and let the water out. It should pour out with authority. This is kind of a judgment call, but the first water is just from the bottom tank and that should be fast, then slow a little as it takes the water through the tubes. If it is screwed up enough to not work it will pour pretty slowly indeed. If it were in my driveway, I probably would just swap the radiator with mine. 6. Pull the water pump and examine the impeller and make sure it is not slipping on the shaft, or that the front is not slipping on the shaft. Reinstall and make sure the belt is tight. 7. Pull the thermostat and see that it opens at around 175F or something like that and opens fully. Basically if it stays open fully in boiling water it will work. You can alternately remove it for testing, but be sure to replace it as it really is needed in hot climates as well. 8. I would check the timing and firing order. Extremely retarded can cause an engine to run hot. 9. Make sure the system holds pressure because if it doesn't, the coolant boils, the vapor bubbles in the head from the boiling have a very low thermal capacity and can't carry heat to the radiator, then the head gets hotter making more bubbles and so on. A coolant rich mixture and pressure makes sure there is no boiling going on. 10. I would check the exhaust with the wide band O2 sensor and see that you are a little rich. I tuned my carbs for around 12.5:1 which I was just assuming. Or check that the plugs are not white also indicating a lean mixture. 11. Fit a flex fan from a school bus type vehicle from the junk yard. It has nothing to do with overheating at speed, but they do work great at keeping things cool at idle. Good luck. | ||
| Christian S. Hansen Grand Master Username: enquiring_mind Post Number: 326 Registered: 4-2015 |
"I checked the filler neck and it read 161F on the filler neck which is plausible. The car seems to run cold. I used a thermostat that didn't really fit so maybe it lets coolant around the edges???" Instead of the above litany of procedures, maybe I should just fit a thermostat that does not fit, as that has seemed to work for you? | ||
| ross kowalski Experienced User Username: cdfpw Post Number: 31 Registered: 11-2015 |
I kind of felt bad fitting it. I bought one from RockAuto for cheap and it was. I pulled out the nicest looking thermostat I ever saw from the car. I didn't test the one I took out which was probably perfect, and didn't test the one I put in which looking at it would have been a wise decision. The one I put in I think needed a seal around it's edge to seal as it was a very loose fit. Even worse, I made the gasket for the neck from the box the thermostat came in which was a little thick. After assembling it I put a pick into the neck hole and the thermostat rattled. Nice. You could remove the thermostat which would rule that out as a problem. It's only a few bolts. Good Luck. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1316 Registered: 5-2012 |
Ross How long does it take your car to come up to running temperature with the loose thermostat? If it's running too cool for most of the time this will cause increased engine wear. My car takes 3 - 4 miles to achieve normal running temperature. If you want to avoid RR prices, why not fit a stant 13558 or NAPA 136. It's worth checking out the following article: https://drive.google.com/file/d/0B61gLtsXt4oqR2hGYlQ1SnRtNGs/edit?pref=2&pli=1 Geoff | ||
| ross kowalski Experienced User Username: cdfpw Post Number: 33 Registered: 11-2015 |
Geoff, Great article. That fusible alloy plug thing is definitely what came out of my car. I'm not too worried about the temp too much, as I probably bought the 180F unit to reduce the chance of pinging with low octane gas. Yes, I run low octane gas. I'm likely also reducing my mileage, but I honestly have not checked. As for the getting to operating temp, I would like to see that happen as fast as possible. Maybe I'll get that NAPA 136, it purportedly opens at 180F ish and has to be better quality than what's in there (read the bypass foot is remotely close to spec) Best. | ||
| Christian S. Hansen Grand Master Username: enquiring_mind Post Number: 327 Registered: 4-2015 |
I was just kidding of course as I though it odd that the thermostat would be replaced without the rubber gasket that runs around the edge and makes it fit tightly and which is also available from Rock Auto for another dollar or two. I guess the positive is that with the loose fit you don't have to worry about air getting trapped at that point. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1317 Registered: 5-2012 |
Running low octane fuel intrigues me. I can understand it on the series II models as the ignition timing of around 12 degrees BTDC allows scope for retarding the engine to cope with the lower octane. The earlier cars which are set at around 5 degrees BTDC do not give such tolerance. As a result I have never tried lower octane fuel. Maybe I will sometime to see if the engine will run on the lower cost fuel. Geoff | ||
| ross kowalski Experienced User Username: cdfpw Post Number: 34 Registered: 11-2015 |
Geoff, Regular seems to run as fine as modern alcohol gas can in my 6.75. I was surprised that the car didn't have a vacuum advance. I think I actually put in a little more advance as I remember. I know I did a little less dwell on the points to keep the coil cooler 25 Degrees?. But I figured that the chambers were hand finished and I wasn't going to be racing it so I run regular. Regular is $2.00USD and premium is $2.50USD so it's a philosophy thing and not a price thing. I'm a Polya guy and not a "git er done" or "it's cheap and can't hurt" guy. I live by Polya's first principle for car repair. It takes time, but in my experience it is always less work overall and it always solves the problem. Best. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2017 Registered: 6-2009 |
Geoff, These cars were shipped to many parts of the world where what we now consider high-octane fuel was not even available. I know people running original Shadow series cars as well as two-series cars on 87 AKI octane fuel without any difficulty at all. I'm one of the latter. Consumer Reports magazine, whose research I trust, has for years said that it is a complete waste of money to use high-octane fuel in any vehicle that will run correctly without it. If you do not have knocking/pinging/pinking when you give 87 AKI fuel a try you're good to go. If you do, then you either need to explore timing tweaks if you still want to try to go that route or simply stick with 91-93 AKI octane fuel. Brian | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1318 Registered: 5-2012 |
Brian I will try it out and report back. If I do get pinking I will revert back to high octane. My car is running well at the moment so I do not wish to re-tune it. It will be an interesting experiment. Geoff | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2018 Registered: 6-2009 |
Ross, Your temperatures are very low (relatively speaking). Were I you I'd definitely look in to replacing the thermostat. It's been said many times here, and elsewhere, that an engine running too cold is subject to more wear over time than one running at the correct temperature or slightly hotter than correct, but not overheating (which to me means so hot that you have boiling coolant or are getting readings on your temperature gauge that are above the white band, whether or not the overtemperature buzzer ever sounds. BTW, it's also been repeately mentioned that by the time the overtemperature warning buzzer sounds your engine is already toast, so it's really not a warning in any meaningful sense of the word.) Brian | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2019 Registered: 6-2009 |
Geoff, Just remember to put in only, say, about 1/4 tank of regular when the car is reading empty. That way you can definitely create a higher octane mix with premium gasoline for the remaining 3/4 tank if the experiment does not show you to have a smooth running engine on regular. I say this because it's very easy, if you're accustomed to just filling up, to do so when you decide to do this experiment and no one wants to have to drain or siphon gas if that can be avoided. Brian | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1319 Registered: 5-2012 |
Hi Brian Yes, that's my plan. 5 gallons and if things don't work out, 15 gallons of premium on top of it. Incidentally, there's a gas station near where I live that's advertising ethanol free gasoline. Haven't seen that before. Geoff | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2020 Registered: 6-2009 |
Geoff, There are little pockets of ethanol-free gasoline sellers in many parts of the country. There are even a number of websites that compile lists of them, in the USA at least. I thought that pure-gas.org might even have been mentioned here before. Brian | ||
| Patrick Ryan Grand Master Username: patrick_r Post Number: 343 Registered: 4-2016 |
Interesting thread this one, it still keeps giving. My car (SRH12255) never gets over 78C (172F) Great in summer, but I cant say I can fault it in winter either, they heater works a treat. However if this is effecting economy (if we can use that term in relation to the 6.75L V8), it then peaks my interest. | ||
| Patrick Ryan Grand Master Username: patrick_r Post Number: 344 Registered: 4-2016 |
Based on the excellent article supplied by Geoff, I am led to believe my thermostat is either the wrong heat range, or it is not closing properly. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2021 Registered: 6-2009 |
Patrick, Also do not be surprised if you find the lead plugs missing, and not from having melted out (or at least that's not indicated by other evidence). The design for the UE36600 thermostat is poor, plain and simple, and its failure rate is unacceptably high. There are thermostats that are better than OEM and that do not carry the ludicrous "replace every 2 years" stipulation. Brian | ||
| Patrick Ryan Grand Master Username: patrick_r Post Number: 348 Registered: 4-2016 |
Agree Brian, I would be shocked if they were still in there to be honest after reading the article. WHY did Rolls Royce make something so over complicated, difficult & controversial as a bloody simple thermostat. They have been very successfully operating in all parts of the world since the mid 20's. Its an all to common thing with these cars, make something that is simple, difficult and thus potentially unreliable. | ||
| ross kowalski Experienced User Username: cdfpw Post Number: 37 Registered: 11-2015 |
Brian, I agree, I like engines quickly getting up to temp and running at 185. I don't really trust the $5 Harbor Freight salvage IR sensor, so I'll thread in a known good sensor and get an actual reading before doing anything. I'd wouldn't be surprised if the temp at the rear left bank was 190 when I was reading less at the thermostat housing. We'll see. I dialed up the dwell on the car this afternoon to 28 degrees for a stronger spark. Dwell is super easy with the external adjuster on this dizzy. I had only set it low to keep the unknown 1970 lucas coil cool, then subsequently forgot about it because the car was running fine. | ||
| richard george yeaman Grand Master Username: richyrich Post Number: 571 Registered: 4-2012 |
Ross in an effort to keep the coil cool on SRH 19529 I moved its position to the offside wheel arch, away from the warmest place that anyone could place it. Richard. | ||
| ross kowalski Experienced User Username: cdfpw Post Number: 41 Registered: 11-2015 |
Richard, Good call there. Unlike our coolant, coils would be happiest in the winter. |
