I have a bit if a dilemma. I have a 1956 Cadillac Series 62 with a 365 ci engine and I cannot locate a temperature sensor on the engine. The dash has an OEM gauge but I am unable to track the wiring. I've been all over the engine as well have others trying to locate one with no luck. Would any one know where this sensor should be or would any one have a suggestion as to an after market set up? I've looked in the usual spots and referenced photos posted on this site but the sensor isnt in those locations. There is a blank plate bolted with 2 bolts to the back of the drivers side head but its so close to the accelerator bracket it doesnt appear a sensor would fit there.
There doesnt appear to be too much room to cut into the radiator hoses to install an inline fitting. Any suggestions would be greatly appreciated.
Thanks
Hawkfan
Quote from: hawkfan on July 14, 2020, 07:14:07 PM
I have a bit if a dilemma. I have a 1956 Cadillac Series 62 with a 365 ci engine and I cannot locate a temperature sensor on the engine. The dash has an OEM gauge but I am unable to track the wiring. I've been all over the engine as well have others trying to locate one with no luck. Would any one know where this sensor should be or would any one have a suggestion as to an after market set up? I've looked in the usual spots and referenced photos posted on this site but the sensor isnt in those locations. There is a blank plate bolted with 2 bolts to the back of the drivers side head but its so close to the accelerator bracket it doesnt appear a sensor would fit there.
There doesnt appear to be too much room to cut into the radiator hoses to install an inline fitting. Any suggestions would be greatly appreciated.
Thanks
Hawkfan
Brian,
The temp sender is located on the front driver (left) side of the engine head, the wire “Green†should run parallel to the head just seating around the block toward the rear up to the main firewall hardness.
Hope this helps..!
See attached. That area on my engine is blank, no tapped hole.
Quote from: hawkfan on July 14, 2020, 08:29:11 PM
See attached. That area on my engine is blank, no tapped hole.
Brian,
Well I’m :o :o this is the first for me..!
Not sure but could it be this car was made for right hand countries and the sender was relocated over to the right hand side head (front side). ???
I’m not familiar with “right side†cars and since the instrument cluster had to be move as well “maybe†everything had to be relocate. ???
Not sure if you checked the other side just for giggles, the sender should be close to the one of the return passages to the water pump.
Would be interesting if someone familiar with right hand cars can chime in. ;)
G'day Jose,
With Right Hand Drive, nothing on the engine is changed from Factory LHD.
With exception to things that attach to the engine to control it, like Throttle linkage.
A lot around the engine, but that is another issue.
Bruce. >:D
Quote from: The Tassie Devil(le) on July 14, 2020, 08:59:32 PM
G'day Jose,
With Right Hand Drive, nothing on the engine is changed from Factory LHD.
With exception to things that attach to the engine to control it, like Throttle linkage.
A lot around the engine, but that is another issue.
Bruce. >:D
Bruce,
Thanks for the 411 (information ;))
Well if that is the case then this one is for the books. :o This is the standard location for the temp sender and there is no sign of the hole for it on that side of the head unless someone had done a great work in covering up. ???
The engine appears to be original. It doesnt appear to have been molested. I was thinking of cutting in a in line port into one of the heater hoses but not sure how accurate this would be. I just want to have a good Idea as to what the temp is. Any other suggestions?
Could someone have done an engine rebuild years ago, and swapped the heads when putting them back on?
Have a look at the back of the opposite head.
Bruce. >:D
Maybe a better picture how it's look like.
Bruce: I doubt that you can switch the cylinder heads, the outlets for the water pump will be relocated at the rear of the engine!
Hi,
You can swap the heads around, the castings are the same, same part number too. It is true the water pump outlet would be wrong, but it could easily be cutout, if I remember right there is an impression where the water pump outlet would be on each end of the head, one would simply have to cut away the casting where this is. The dead give away here for me is that his head, on the end by the firewall, has a plate with 2 bolts in it, this is where the original water pump outlet would have been, and indicates that the head was swapped around. The only other difference between the heads is the temp sending unit isn’t in the one head, which is why he has no spot for one
Michael
Roger,
Thanks for posting the picture, I did not have one handy on my side so had to use one online.
Michael,
I took a quick peak at my spare heads and there is no cut-out markings on the rear of either R or L side. There is the freeze plug at the same location on either rear or front and the water pump opening is just about ¼†from the freeze plug.
So there is a possibility that someone had used the right side head and mounted on the left side and gone to the extra effort in machining the opening for the water pump outlet. ???
Since the right hand head does not have any opening for the temp sender, good observation and point…! ;)
Brian,
You may have a unique setup if the previous owner had gone to that much trouble in fitting the right side head on the left side as Michael stated.
The problem is you need to place the sender on the outlet side of the block feeding the water pump at the thermostat housing.
In your particular case there is not much you can do to fit the temp sender. You may need to rig some pipes/fittings on the rear cover plate to place the sender there, or you can try it on the right side of the water pump the pipe that feeds the thermostatic valve for the heaters. :(
Best luck..!
Thanks to all for their input!!! It sure is an unusual situation! Seems strange that there wouldnt be a temp sensor as this car was purchased in West Las Vegas and spent most of its life there. I think I'm going to get as close as I can to the water pump and insert an in line sensor adapter in one of the heater hoses. It wont be perfect but at least I can monitor the engine temp to see if it is climbing.
Thanks
Hawkfan
Sometimes people have to use what they can get hold of, and if his original head was unserviceable, and finding one that would fit, with modifications, sometimes people just do it.
I had to work on a '71 Eldorado with a seized engine, and it turned out that someone had replaced one of the heads with a '74 or '75 head.
Had trouble tuning it up, and the discrepancy was found when finding that the pushrods on one side were pushing the valves earlier than the other side.
Had to find a 75cc head to replace the 125cc, and yes, I had to use one of my own spares.
Now I have a spare 125 cc head that has been reconditioned for sale.
Bruce. >:D
This is a fascinating topic. My initial thought was that someone had either swapped the heads or exchanged them for a set designed for another vehicle. Then Hawkfan's comment about a "blank plate with 2 bolts" stood out. Having owned or examined about 10 pairs of 1956 Cadillac heads over the years I did run across a driver side head that also had a rather thick plate with 2 bolts at the back close to the firewall. I have no idea what that was for, as I believe the other heads did not have that. To me it seemed not feasible to attach a hose there or even a (conventional) sensor. Very little room. It also appeared to be factory. Unless it is just my poor memory, I do not think the other heads that I have seen had that. Earlier in this Forum I posted information regarding issues that GM had with the 1956 Cadillac engine and in particularly the cylinder heads. I wonder if that blank plate was related to a quick fix idea that GM subsequently abandoned? My posts provide evidence that some heads may have been flame hardened, though this is not conclusive at this point. GM did make changes although I noted that they did not advise what all of those changes were. Would be interesting to have the 2 sets of numbers from your engine, as well as the head's casting number. If your heads were swapped, that might explain the blank plate, to cover a water galley port. That would also explain why there is no sensor on that side. Of interest is that my head with the blank plate at the back DID have the heat sensor in the proper place, up front near the water pump galley. Would be nice if you could provide us with some numbers and more photos with as much details regarding this plate. I shall go and have a look at mine. Clay/Lexi
I'll get the numbers requested later in the week. I ordered a port that I will cut into the heater hose just to the drivers side of the water pump. That should give me a rough idea as to the engine coolant temp.
I'll let you guys know what the numbers are then. I have a question about heater hoses but I believe I should start a new thread for this subject.
Thanks Again!
Does the temp gauge work or not?
You can trace the green wire out of the taped bundle at the fire wall. It should have an insulator sheath over it over the motor but they deteriorate.
If it's not working, look to see if was clipped or dangling at the firewall.
I see something "unusual" dirt/grease covered where it should be but can't make out what I'm seeing even with magnification.
I believe it's a 3/4' NPT fitting(pipe thread) for the sensor. That won't be covered with a plate, unless they replaced the plate with a hole with one without a hole.
You can check and see if temp was deletable in the specifications, but I doubt that was an option. Might be a case of not seeing and not noticing.
Roger,
Here is a picture the back side of my 1956 heads, mine have a flat raised area on the back of the head, the would seem to me to correspond with where the water pump would be mounted, when compared to the front side, it’s in the right location, and the right shape and size. I always figured the one bolt for the ground strap would be / could be used for the top water pump bolt. I’m not a machinist, but certainly looks feasible to me. I believe mine are the early version of 56 heads. My ‘57 heads don’t have the same raised area, but that area is machined very smooth,
Michael
Quote from: M. Bankes on July 16, 2020, 08:51:35 PM
Roger,
Here is a picture the back side of my 1956 heads, mine have a flat raised area on the back of the head, the would seem to me to correspond with where the water pump would be mounted, when compared to the front side, it’s in the right location, and the right shape and size. I always figured the one bolt for the ground strap would be / could be used for the top water pump bolt. I’m not a machinist, but certainly looks feasible to me. I believe mine are the early version of 56 heads. My ‘57 heads don’t have the same raised area, but that area is machined very smooth,
Michael
Michael,
That opening is where the freeze plug would be, you can see the lip inside where it should seat inside. The bolt on the left side would be for the ground strap and the small plug at the bottom is for the oil passage.
My spare heads do show the same marking although a bit less pronounced. If you check the other side were the pump bolts, the outlet would be just around the top corner just about ½†â€" ¾†from the freeze plug opening which both sides have.
Interesting pic from Michael. I'll have to look down that back side one more time.
I purchased and installed a temp gauge and inline port in a heater hose just off the water pump. It gives me an idea as to what the temp is.
I havent really been able to get under the dash to check the temp gauge wiring as the power seat is pretty much stuck in one spot where I cant really get my body in the right spot. A project for later in the year, to fix the power seat.
Clay had asked about casting numbers on the engine. I was able to find the following numbers: on the block is 8N21 and on the intake manifold is 1464176 3. These are the numbers I can locate without tearing into the engine.
Hawkfan, thanks for the numbers. The intake manifold number is correct for a 1956, single 4bbl carburetor. Not sure what the other number is. The most useful numbers would be the one on the RH side block, top side closest to rad. Might be obscured by AC compressor if installed and/or generator. That is where one location of the vehicle's VIN number is. Yes, it is located in 3 other areas but the one on the engine is important to determine if it is number matching, (engine may have been swapped out years earlier). The engine's serial number is stamped on top of the cast iron bell housing, LH side below the cylinder head at rear. That one can be tough to see and is often faint and obscured with grime and corrosion. That number can contain a wealth of information.
Here is a shot of the rear of that LH cylinder head on a 1956 Cadillac engine. It shows the plate and 2 bolts, close to the frost plug. Looks original to me. I may remove valve cover to see what the head's casting number is. Does this blank plate and 2 bolts match yours???????? Anyone ever see one of these, even if on another year of Caddy engine? The block it is attached to is a 1956 365 V8. Came out of a major Cadillac collection and was told was running prior to parking and removal. Never seen one like this before. Clay/Lexi
Edit: Temperature sending unit is on this head in the usual place.
Lexi,
Thanks for the guidance. I'll do some more searching for additional numbers.
Yep, that "blanking plate" is exactly like mine and in the same spot! I thought about making another plate and tapping a hole for a temp sensor and installing it but the location is so tight up against an accelerator bracket there would sure be interference issue.
Thanks
Hawkfan
When I read about this I got curious and looked at mine to see if they had the sending unit in the correct place. Both of my 56's are there. My 55 though, has it on the rear of the left head, right where that plate is. It doesn't have the plate on it though, it's just tapped and threaded.
Just thought I'd mention that in case you were thinking of putting your sending unit in the rear of the head.
Rick
Realistically, he best place for the coolant temperature sensor is as close to the engine-side of the Thermostat, where it can register the highest temperature before it can be circulated into the Radiator.
Bruce. >:D
I tried to make some sense of this puzzle, for my own edification. I could not locate a good illustration showing the '56 sensor position in the archives. (doesn't sell cars)
The parts list shows the temp sensor changes, '55 to '56. '56 should be the same thru '59, front left(DS) head, as shown. That's the single pin Delco w/ 3/4 NPT. The '56 one pictured would be correct. Important clue; that's not what is here. Neither '55 or '56 sensor in position.
The '55 sensor has a threaded end electrical connection, so the signal wire end connectors are different. Pictures are available(ebay) and goes in the back of the head, '55. The signal wire would be shorter and won't fit the '56 connector. Most likely, someone blanked off a '55 head and did away with the sensor as it didn't match the wiring. Really no reason, otherwise, to disconnect, unless the indicator/gauge doesn't work either.
This engine does not appear to be all original '56 and why there's no sensor.
As advised, make sure the VIN number matches to be sure it's even a '56 block.
Yes, I would love to see some block numbers as well. For those historians out there, the LH head I wrote about with the blank rear plate, does have the heat sensor. I believe the sensor is in the correct place, up front near the water pump top arm. As I wrote earlier in this thread GM admitted to making a number of changes to "major mechanical parts " (quote), as per the December 23rd, 1955 General Service Letter #896 for the 1956 Cadillac model year. The specific changes were not described, though it was noted that many were "dimensional". The Master Parts List notes 2 different part numbers for cylinder heads that year, with all sorts of provisos noted, (linked to various engine unit/serial numbers). Same for camshafts that year as well. Hopefully hawkfan can locate some of those numbers and post for us. That will give us something to chew on during these Covid times. :) Clay/Lexi
Edit: Photo image of my Cadillac's engine compartment showing location of heat sensor, close to water pump. See red arrow which points to the mechanical unit I installed, rather than rely on the OEM sender. Same location for installation though.
I happened to pull the radiator to have it re-cored as it had a leak and I was discussing the lack of temp sensor location on my engine with the radiator shop owner. This individual and his shop harkened back to the day of mom and pop parts stores. When I brought the radiator into his shop he knew just by looking at what car it came out of. He suggested that while he was rebuilding my radiator that he could braze a fitting into the top bonnet at the core line so I could install the probe there. Sure enough. I installed the radiator and the temp probe into the fitting and as soon as the thermostat opened the temp gauge went up to 190 deg. Shops and owners like these are very few and far between. Trying getting this service from one of the big parts outlets! Never happen!
Glad to hear that you got the problem solved. The one drawback to the new location is that you don't really know what the engine temperature is exactly until the stat pops open. Another thing that you want to consider is if your stat should stick closed, you won't know that either until it's too late.
Just food for thought.
Rick
Yes, Cadmaniac makes a good point. What happens if your thermostat sticks shut? Those Harrison radiators were used on Cadillac from 1949 - 1956. Only difference on some years is where the drain cock was placed. Clay/Lexi
Before this modification I hadn't a clue what the temp was. Now at least if the temp gauge doesnt move after I drive it for a bit I know something isnt correct. For how I drive this car, this probe location works.
Definitely an advantage. In this hot weather I note my mechanical gauge shows clear signs of movement at least within 1 - 1/2 minutes of fast idle. Then after a 2 - 3 mile drive it would be at around 180, i.e. about opening temperature of the thermostat if working. Clay/Lexi
Brian,
You're so fortunate to find and employ the services of such good people. Having owned my share of "vintage" Cadillacs, most independent repair services think you're an old crazy man to dump money into a beloved car. As one guy told me some years ago, "Why would you want to feed a dead horse." I have moved to Maine, and discovered a wonderful garage, owned and operated by brothers who charge 65 dollars an hour, and they're respectful, creative, intelligent, and use a variety of internet services for research. I wish the Club would develop a " National Register of Supportive Automotive Repair and Restorative Shops." Reciprocal advantages would more than provide ROI for all parties. Happy day, James
James,
Couldn't agree with you more!!! Glad to see you've found a shop you can trust and not get taken to the cleaners by. I've rebuilt several vintage cars for myself and others over the years and its something I enjoy doing! I've made some money at it along the way but I love driving them more. I enjoy the challenge and enjoy meeting people that share the same passion. In this day and age, most people are clueless when it comes to getting their autos repaired. They're at the mercy of the repair shop!
Enjoy the ride!
Hawkfan