| Author | Message | ||
     Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 237 Registered: 4-2015 |
Re: Silver Shadow 1979 SRK37338 Please pardon all my questions with this new acquisition. On top of the split radiator top tank and difficulties getting coolant filled back in successfully, I fear that there is a problem with the temperature sender or gauge, or both. Even during these heating episodes the indicated temperature never even began to show hot on the gauge. Hottest reading on gauge has been maybe 1/8" into the low part of the white band even when the coolant was boiling and steaming out of the crack. I think that it is safe to say that this is not proper. So...I am wondering how to verify the sender and the gauge. I found the attached photo of the thermostat housing (which seems to be the same as mine) in the manual (TSD4200), but there are three sensors. What are their purposes and which is the temperature gauge sender? Perhaps the parts manual gives this information, but I did not see a parts manual in the technical library. I supose that I could get a temperature gauge from an auto parts store and connect it into the sending unit somehow in order to get a reading that could be compared with the gauge, or am I on entirely the wrong track? I am not thrilled with the fact that the engine coolant got hot, for unknown reasons, and burst the seam on the top tank and the gauge that might have otherwise given some warning, left me entirely clueless as to the developing problem. The cloud of steam was the less preferable way of finding out! Ideas?  | ||
| Jeff Young Prolific User Username: jeyjey Post Number: 256 Registered: 10-2010 |
Hi Christian, If memory serves, the upper two are open/closed contacts. The one above the thermostat is for the electric fan in front of the radiator, and the one below the thermostat is the fan-delay switch (to keep the heater fans from coming on until the water is hot). (Note that they switch at two different temperatures.) The bottom one is analogue, rather than on/off. That's the sensor for the temp gauge. (I think US cars have a third on/off switch for the EGR mounted between the top one shown in the picture above and where the radiator hose connects.) Cheers, Jeff. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1949 Registered: 6-2009 |
Christian, Please see the thread entitled, Those darned thermostat housing Otter switches - which switch does what?, along with the thread I reference in the first post of this thread. Of particular interest will be my offering of 03 December 2015 near the end of this thread for the sensors that were carried over from the SY to SZ cars. Between Randy's find and this information you should be set. Brian, who knew I'd just been through all this in recent months | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 238 Registered: 4-2015 |
Brian and Jeff... Thanks for the information. I recalled Brian's posting but have not yet mastered searching on the forum for it. Is there a feature where you can select posts from a particular member, rather than key words? Anyway, now that the coolant temperature sender for the gauge has been locaoted, what does it take to hook up an auxilliary gauge to the sending unit? | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 240 Registered: 4-2015 |
Let me expand on this. I am thinking that there must be a way to test the sending unit in site. I presume that there must be readings (ohms or whatever) that vary as the heat increases. Would anyone kindly enlighten me on this? Clearly that test should be the first to be performed, prior to doubting the gauge. Here is the possible scenario, and forgive my skepticism, paranoia, or lack of faith in human nature. Let's say that you have a car that overheats and you wish to sell the car. It is clearly undesirable if the gauge should show the overheating problem. Solution? I assume that one could "fool" the gauge into giving a "false" reading by simply replacing the sending unit with another that is calibrated differently...or are all sending units the same? This scenario would certainly explain why the engine appears to run hot while the gauge barely gets into the white band. If such an "adjustment" is possible, it certainly is easier to replace the sending unit than to fuss with the gauge. So...bottom line is that I would like to test the sending unit for proper readings. How? Thanks!! | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1950 Registered: 6-2009 |
Christian, I cannot tell you precisely what your readings should be, but you are definitely on the right track with regard to these things being thermistors where resistance varies with temperature. If you were to buy any random temperature sender you would be able to see the general sort of behavior you would expect. I recently had the coolant temperature sender go out on my Buick, but I did not do any experimenting to see what the functioning replacement did versus the dead one since good, new OBD-II pointed me directly to the dead item. Brian | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 241 Registered: 4-2015 |
Brian... Thanks for the reply. Perhaps someone will know the proper readings that would make the dash gauge read the accurate temperature...which when using a quality infrared heat gun indicates 235-240F at the thermostat housing and 210F at the radiator core, and yet the dash gauge barely gets into the white band. This is exactly the opposite of the issue I discussed at length (can't find the thread however) two years ago with my MPW coupe (CRX2541) which had idential temperature readings, but the dash gauge read just a fraction under the "HOT" dots. At that time you surmised that there was nothing amiss, to stop worrying, and that those temperature readings (in ambient climate of 70F) were appropriate. My concern then was the same as now. If appropriate, why did the dash gauge not read "normal" rather than "you are just short of a crisis"? Call me particular, but I would like my indicating gauges to tell the truth, and neither cars seem to be providing those facts accurately. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1951 Registered: 6-2009 |
Christian, With the MPW you would not believe what objective data other than the gauge were telling you, all of which indicated that everything was WNL *except* for the gauge reading. In this instance you have objective observations telling you that something is wrong in addition to the gauge reading, which has pretty much got to be wrong given what has occurred. In the former you were worrying needlessly and now you have something to be concerned about in addition to the gauge reading. The commonalities are a bad gauge reading and cooling systems, and not too terribly much else. With regard to the readings from the sender, unless you are very lucky that information is not likely to be forthcoming. It is abundantly clear to me that these either work, so if you know something that approximates what a normal reading curve would be for a functioning sensor you'll be able to immediately recognize an utter lack thereof. When the Buick's died if I cleared the OBD-II code it would reset itself almost instantly, whether the car was dead cold or had been running and thoroughly warm. This strongly suggests that either zero resistance or infinite resistance characterizes a dead sender. I hope someone can give you the reading data you need, but if not you have to start thinking about how you identify "dead" versus "possibly working" first. You can also have the key in run position, a small quantity of very hot water in a container, and the lead connected to your new sample sender just to see what changes show up on the gauge using it. These sensors are not particularly precise, particularly outside a certain temperature range. If you have one that matches the temperatures that were shown in the other thread I've pointed you to you should have "close enough" to at least see if the gauge itself is reacting at all to input from a functioning sender. Brian | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 242 Registered: 4-2015 |
Brian... As always, thank you. There is no question of whether the sender in dead. It is not dead. It responds as the water temp warms. It just does not end up in a satisfactory position. Out of curiosity on the issue, and while I am basically in "twiddle my thumbs" mode and awaiting the arrival of the replacement top tank, which when installed, will at least remove the "inability to properly pressurize the system" portion of the equation, I checked the switches at the thermostat housing and can see that the gauge temperature sender has been recently replaced. "Why" remains the mystery, but it does support the theory that the wrong sender has been installed, either inadvertantly, or deliberately. Your idea of obtaining another generic sending unit, connecting it to the existing wiring to the gauge with ground, and placing into a pan of boiling water to see how the gauge reacts is good investigative thinking! | ||
| Omar M. Shams Grand Master Username: omar Post Number: 684 Registered: 4-2009 |
Dear Christian, take the sender unit out and place it in a cup of boiling water and a thermomemter. Look at the thermometer and correlate what you see to the gauge in your car. If at 99 degrees C the gauge is reading low - you have hit the nail on the head. You dont need anything more fancy at his stage. | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 244 Registered: 4-2015 |
Omar... With a bit of research I have found that a "substitute part" for the Crewe UE40361 is a GTR101, commonly used on MGB, Mini, and some Rover. A bit more research revealed the "ohm" resistance for that GTR101 sender, which "presumably" is the same as the RR part. Tomorrow or the next day I will purchase a multimeter and check the resistance of the sender in place to see what readings display. Depending on the results, if at variance with those expected, I can then purchase one of the GTR101 units, install it, and see what happens. Meanwhile, hopefully the replacement top tank will turn up later this week. | ||
| Omar M. Shams Grand Master Username: omar Post Number: 685 Registered: 4-2009 |
Dear Christian, please don't fall into this trap. I did this 20 years ago and found out that the British Leyland sender units read low on our cars. Get the real part from a Rolls-Royce or form a reputable RR parts supplier if you want to be sure. Thanks Omar | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 245 Registered: 4-2015 |
Omar... Thanks for the "heads up". I wonder if that is the existing problem...installed sender is not Crewe and thus reads low. If so, that is why the gauge reads low! I will take a look at it again to see if there are any part numbers visible. The specs given for the GTR101 are 800 ohm @ 20C and 50 ohm @ 90C. Can anyone verify if theirs reads out at those specs? | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 246 Registered: 4-2015 |
Photo of the sending unit. Imprint looks like B720. Is this a Crewe UE40361, or otherwise? Comments? Thanks! 1979 Silver Shadow SRK38337  | ||
| Omar M. Shams Grand Master Username: omar Post Number: 687 Registered: 4-2009 |
look at this link to get an idea of the sender unit you have in your car.... http://www.7ent.com/products/temperature-sending-unit-red-gtr0104.html | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1283 Registered: 5-2012 |
Christian Could be the plumbers tape someone has put round the sender is causing a bad earth. I would never use plumbers tape on a sender plug. Geoff | ||
| Jeff Young Prolific User Username: jeyjey Post Number: 257 Registered: 10-2010 |
+1 to Geoff's comment. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1954 Registered: 6-2009 |
+2 to Geoff's observation. PTFE is a wonderful insulator and has no place where any electrical circuit needs to be completed, not insulated out of existence. Let's not get into the fact that the pipe thread style used for these things is designed to form a good seal without any additional assistance and generally does so, with rare exceptions, if not torqued so much as to permanently distort the threads. Brian | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 247 Registered: 4-2015 |
Geniuses, one and all! That neven dawned on me. I was looking at the white teflon tape as an obvious indication that the sending unit had been recently replaced, which it is, but failed to recognize that it might cause a grounding problem, which could be the source of the reading error at the gauge. If what has been proposed is valid, and it clicks with me as being so, I am surprised, no, shocked that such was done by a well known and presumabley very experienced RR shop. I will now remove the sender, remove the tape, and see what happens. THANKS, GUYS!! | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 248 Registered: 4-2015 |
Omar...Yes, Genius! Thanks for that link. Adding insult to injury, and based on the information at that link, the sending unit installed (GTR0104) is the incorrect part!! I am doubly shocked, no flabbergasted! What else can I say? Not only does the tape need to be removed, but a suitable sending unit needs to be installed. At this point, my paranoid skepticism kicks into high gear and provokes wonderment as to what else has been botched on this car. | ||
| Nigel Johnson Prolific User Username: nigel_johnson Post Number: 158 Registered: 12-2008 |
Hi everyone, I recently fitted temp transmitter VE718035 to our 1980 Spirit and it works perfectly. Black plastic top by the way. £7.07 plus VAT. Regards, Nigel. | ||
| David Gore Moderator Username: david_gore Post Number: 2073 Registered: 4-2003 |
The senders usually have a tapered thread to provide proper sealing and electrical continuity. Parallel threads usually require thread tape for both stopping leaks and facilitating later removal when necessary. I would be certain the sender was not replaced by an experienced mechanic as they would be aware of the need for electrical continuity for the sender to function properly. | ||
| Patrick Ryan Prolific User Username: patrick_r Post Number: 250 Registered: 4-2016 |
Great learning here gents. Thanks for all the replies. | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 250 Registered: 4-2015 |
David... Of course I cannot say whether your confidence is or is not misplaced, and perhaps my conclusion, based simply on the "clean" appearance of both the white tape and sending unit body...not a speck of soiling, oil, dirt, or grunge that would accumulate and indicate extended use is without merit, but it is perhaps supportive of recent service, and further, is confirmation that upon the acquisition of a "new to you" vehicle, you cannot assume anything, and that if you have not personally done it, or witnessed it being done, you have no idea what was done, or how it was done. It harkens back to the advice I noted elsewhere, that if someone assures you that it is not A, B, or C, the first things you need to check are A, B, and C. At the very least it would appear that we have uncovered two problems (use of teflon tape and incorrect sender) that can possibly be contributing to the inaccurate gauge readings. | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 251 Registered: 4-2015 |
Nigel... Thanks for the tip to the "VE718035" temperature sender. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1955 Registered: 6-2009 |
From the Cambriare Technical Brochure, these are the people who make the VE718035 temperature sensor:  Interesting that this company, based in Italy, has close connections with Pierburg, too. Brian | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1284 Registered: 5-2012 |
Hi Christian Yesterday you mentioned you were going to buy a multimeter. Have you had the chance to do so yet? If so you could measure the resistance between the brass head of the sender (not the terminal) and ground. You should get zero ohms. It would be interesting to know what figure you get. Geoff | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1956 Registered: 6-2009 |
Another interesting couple of bits of information and inferences I'm willing to draw based upon same. See this manual page from Minispares.com that shows up for the GTR104 temperature sender. It lists three different thermostats depending on era and model of mini: GTS102 74°C/165°F GTS104 82°C/180°F GTS106 88°C/190°F and the following temperature sensors: GTR101 (alternative for GTR102/GTR143) GTR104 I would be shocked if the corresponding last three digits did not "pair" in practice such that a GTS102 thermostat and GTR102 (now GTR101) were not used together, etc. Now, if you are willing to buy my inference this would suggest that GTR104 sender likely centers around 82°C/180°F as far as its resistance curve, since you'd want to know when the coolant temperature was approaching the thermostat opening temperature (definitely on the low side of whatever is the normal range) through about 25 degrees above opening temperature (as the upper range of normal, since no cooling system "tops out" at thermostat opening temperature - there's always more heat soak after it's open over extended driving time). The UE36600 OEM thermostat for the SY series cars is rated at 190 degrees F, so I suspect using a GTR104 temperature sender would most likely "read high" on our gauges, as it's most likely intended to be mated with a thermostat with a temperature rating that's 10 degrees F lower than the OEM thermostat. It will also be interesting to see if the figures quoted from the Cambriare Technical Brochure apply "universally" as far as the expected resistance values as temperatures increase, but what shifts is not the resistance values but when they start kicking in and when they reach their minimums (since resistance decreases with increasing coolant temperature). If this turns out to be true then using a sender that's intended for a thermostat designed to open at a lower temperature than the UE36600 would be giving you "high temperature" readings before the correctly rated sender would. Ah, the fun of investigation!! (Even when I'm not carrying it out). Brian | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1957 Registered: 6-2009 |
And, finally, see this page on the blog Diary of an MGB regarding temperature sensors, testing same, and differences in readings between replacement units as they've been changed to different part numbers over the decades. The most interesting observation, in my opinion, is that of "Anonymous" near the very end of the page:
| ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 253 Registered: 4-2015 |
Geoff... No, not purchased yet. Although on my "to do" list for the past few days, other issues have prevented me from acquiring the multi-meter. Meanwhile, please clarify your test. Do you want it done with the offending teflon tape in place, or after the tape has been removed and the sender reinserted into the housing? From what I "do not know" about these things, with the tape removed, the resistance should be about "0" since you are basically measuring from ground to ground...same as if you touched the probes of the multimeter together. Yes, so far? However, with the tape in place, the tape is theoretically, and at least to some undetermined but to be expected degree, creating an insulating effect between the sending unit and the thermostat housing (ground). Yes, so far? If that insulation is 100% effective, the resistance should be infinity because it is like having the two probes of the multimeter not touching each other due to that insulation. Yes, so far? Since the teflon tape has been compromised via the threading of the sending unit into the housing, it should not be unexpected that the insulating qualities are not perfect and that there will therefore be some degree of contact with the ground. Depending on the effectiveness of the insulating effect caused by the presence of the tape, whatever that amount is will certainly skew the resistance being received by the dash gauge. Yes, so far? It is my suspicion that the tape is causing the resistance to be skewed and that is quite possibly the cause for the gauge reading low. Now as far as "what to do" next, and before I get too involved in experimental readings, et cetera, I am inclined to address only one thing at a time and that will be either replacing the top tank (as soon as it arrives) which will allow me to run with a properly pressurized system, or removing the tape from the sending unit and seeing how that changes the dash gauge reading. Brian...I am grateful for your talents with finding this technical information, but I will defer trying to put it into the context of whether the sending unit is proper or not for the moment, at least until the noted two obvious issues (tape and top tank) have been addressed and their effect on the dash gauge reading determined. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1285 Registered: 5-2012 |
Hi Christian We are on the same page. To clarify my test, set the multimeter to measure resistance. Then place the probes as indicated by the red lines in the picture below. This is with the sender unit in place and undisturbed. So a very simple 2 minute test.  There are 3 possibilities. 1) Infinite resistance which means the tape is completely insulating the sender unit. I doubt this will be the case as you would not get any movement on the temperature gauge as the engine heats up. 2) Zero Ohms which means the sender is grounded as should be the case. This may be because the person who used the tape did not cover the entire thread or the tape was broken as the sender was tightened. This is a good possibility and the problem is solely with your sender unit. 2) x ohms measured, meaning the tape is offering partial resistance. If this is the case it would explain the behavior of your temperature gauge. When the engine is cold the sender will be at maximum resistance. As the engine warms up the resistance in the sender will decrease, causing the temp gauge to move up. However, at some point in the heating of the sender the resistance will not change and the gauge will stay steady even though the coolant temperature is still increasing. This is because the resistance caused by the tape will prevent the lowering internal resistance of the sender to be seen at the gauge. At that point the gauge is reading the resistance of the taped joint, rather than the lowering internal resistance of the sender unit. I'm a little concerned that fitting a replacement header tank without removing the underlying problem may cause that one to blow also. I agree with David, walk away for a few days and come back refreshed. If I was in this situation I would remove the radiator and check for blockages, replace all the hoses and back flush the engine and heater matrix. This is not a huge job and being able to carry it out from the top of the engine, rather than having to crawl around underneath the car, makes it a quick win. Geoff | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 255 Registered: 4-2015 |
Geoff... I am sure that your analysis is spot on with number 3. The problem with your other suggestions is simply that I have a bad feeling about this car for reasons that I will not detail. I have decided to sell it and the dealer from whom it was purchased, while refusing to take it back outright (which by all rights, he should), has at least relisted it for sale on my behalf, but has asked that I not do anything else to it other than the top tank. I will take the liberty of removing the teflon tape, out of sheer curiosity. It is a pity because I really like the color, interior, and overall condition of the car and it is not surprising the number of compliments that it provokes. It is the "under the hood" that is problematic. It really could be a nice car for someone who does not mind putting everything right, but that is not what I either bargained for, anticipated, nor have time for. Acquiring the Shadow was a whim that turned out to have been improperly contemplated. Time is short in life and I have a '34 Phantom II that will take first position in the garage once this Shadow is gone. | ||
| richard george yeaman Grand Master Username: richyrich Post Number: 519 Registered: 4-2012 |
Hi Christian when this car is put up for sale will its service history be divulged or will the prospective buyer be told the same bumph that you were told before you bought this car ? Richard. | ||
| Patrick Ryan Prolific User Username: patrick_r Post Number: 251 Registered: 4-2016 |
Hi Christian, Can we see some of the beauty of this car you have described? | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 257 Registered: 4-2015 |
Richard...I cannot speak for the dealer, although I am sure he will answer any question that you have, and I can forward the records and information sent to me. Patrick... I will post some photos later this evening. | ||
| Patrick Ryan Prolific User Username: patrick_r Post Number: 254 Registered: 4-2016 |
Thanks Christian, Will look forward to seeing them. | ||
| Christian S. Hansen Prolific User Username: enquiring_mind Post Number: 259 Registered: 4-2015 |
Patrick... Here is a single photo and the link to the current EBay listing. http://www.ebay.com/itm/Rolls-Royce-Silver-Shadow-II-4-door-sedan-/262485026566?forcerrptr=true&hash=item3d1d53a706:g:PiMAAOSwiYFXJ-EV&item=262485026566 The proprietor does take marvelous "glamour" photos and since there are over 100+ the entire listing will take a while to load, a long while depending on your internet connection speed, but the wait is worth it. Simply a gorgeous, head turning car.  | ||
| Mark Aldridge Grand Master Username: mark_aldridge Post Number: 317 Registered: 10-2008 |
Christian, do you have the paint codes for this car. I presume one is 9510234, but I am intrigued by the other. The combination is great. Mark | ||
| Jeff Young Prolific User Username: jeyjey Post Number: 258 Registered: 10-2010 |
Stunning colour combination (inside and out). Why not just take it to a specialist and get them to sort out the cooling system? (I wouldn't be letting that car go....) Cheers, Jeff. | ||
| Patrick Ryan Prolific User Username: patrick_r Post Number: 256 Registered: 4-2016 |
I have to agree with Jeff Christian. Lovely car, lovely combination. Love the Shadow I bars as well. Thanks for posting the pic and the link. |
