Temperature Sensors for 1972

[The Tassie Devil(le)]

G'day all,

I am requiring two Engine Block Temperature Sensors for the 1972 500 that attach to the Cylinder Heads.

One is the Block Sensor for the A/C that goes in the Right hand head, at the front, just to the rear of the Alternator, (operates at 120 F) and the other is the Overheating Block Sensor that fits onto the rear of the Left Cylinder Head. (Operates at 295 F)

Any idea where these can be purchased, or are they still available at the Cadillac Dealerships.

Thanks,

Bruce.

[TJ Hopland]

Its been kinda hit and miss for me on them lately.   Some people list them but you don't get the correct part either physically or even close temp wise.  I gave up and found a vendor that was willing to sell me a grab bag of used as is ones but have not had time to test em yet to see which ones they are or if they work.  I believe 80's they had similar sensors but went to metric threads.  Cadillac was the only one with the metal temp sensors and they did vary the temps over the years so that is one reason for different part numbers and confusion.  Other makes with auto climate control had the other sensor but on some of them it was a 2 terminal so you have to run a ground wire to the other terminal.  I got one of those for a project then ordered another from the same vendor and got a totally different sensor next time with the same part number on it.  There is a diesel sensor (ford I think) that worked for the climate one but I can't remember where I read about that to find the part number at the moment.   

[Scot Minesinger]

Never have been able to find the 120'F unit that activates the climate control heat delay.  I restore these systems and that switch completes ground when temp on head reaches 120'F.  Usually I just ground that wire going to the switch so there is no delay.  The delay was useful when the car was parked outside on a cold winter day, but that is not how the Cadillac is used today.

["Cadillac Kid" Greg Surfas 15364]

G'day Bruce,
I sent you a PM.
Greg Surfas

[The Tassie Devil(le)]

G'day TJ, Scott and Greg,

TJ.    I didn't realise there were so many different types.

Scott.     I just knew it had to be worthwhile, and every time my own Caddy starts up, the Heater really comes on and strong with warm air as soon as the block is up to temp.

Greg.   Yes, I received it and thanks very much for the information.

I was going to reply directly to you with a phone call, but wanted to wait till you were awake, as nothing worse than getting the phone ringing just after going to sleep, or at 3am.

Bruce.

[Scot Minesinger]

The 120'F sensor behind alternator is not in use during a/c, and it is only beneficial if it is real cold outside and only for the first mile of travel.  Given that these cars are not driven on real cold days, this sensor while a good idea for Caddys parked outside driven by ladies with bare ankles, it is of no value for the use pattern today.

["Cadillac Kid" Greg Surfas 15364]

Scott,
If you are talking about Winter, and the outdoor temperature is say 40 degrees, It doesn't matter what the temperature in the garage (if so parked) is when the car gets outside, if the Fan delay switch is not in the circuit, as soon as you are out of the garage you are getting 40 degree air blown on you.
The switches are available albeit costly, so why not utilize all the "advanced" features the ATC enjoys?
Greg Surfas

[Scot Minesinger]

Greg,

Where can you get the 120'F switches?  Others like you want the delay.  Time, availability, and etc are more of a barrier than price.

Maybe I drive my Cadillac in Virginia a dozen times, compared to a hundred, when it is 40'F or colder outside.  The garage is nice and warm, heated to 70'F always.  By the time the inside of the car even starts to chill (thermal inertia) when it is below 40'F, the car is warmed up and the heat is nice.  We all have our tolerances, and this delay is just not a luxury I'm very excited about.  The thing about the no delay I like is that when the fan starts you know the system is working.

I just don't think the delay is worthwhile, to each their own.

["Cadillac Kid" Greg Surfas 15364]

Scott,
A lot of drive our cars as daily drivers.  My "new" car is my '76.
Greg

[George D. Mukalian CLC # 10047]

I HAVE A COUPLE OF THESE SENSORS. THEY ARE COLOR CODED BUT I DON'T KNOW WHICH COLOR REPRESENTS WHAT TEMPERATURE.
DOES ANYONE KNOW??

THANKS,.
GEORGE

["Cadillac Kid" Greg Surfas 15364]

George,
Both replacement Delco numbers D-1870 and D-1872, the sensors for the Right and Left head (respectively) are bare aluminum with identically colored plastic  insets.  Where and from what car are you sensors from?
Greg Surfas

[Scot Minesinger]

Greg,

Greg,

I had no idea people drove these cars as their daily driver.  Was thinking of doing that in like ten years, or maybe buying the new Cadillac S class fighter due for introduction in 2016 or so (I would buy it 2 years old).  Need a car that seats five, rear drive V-8, am I asking too much?  I used to drive 30k miles a year, and it just seems like a bad thing if I were to wear one of these treasures out that way.  Now, I drive more like 15k miles a year.  Use a truck much of the time.  I would hate to drive an older Cadillac how I drive my truck.  Always in a hurry hectic life right now, just can't bear to subject my Cadillac to that type of driving.  Sometimes I forgo driving my convertible on a beautiful day because I'm in a hurry and won't enjoy the drive very much.  In about 10 years will be slowing down and then like you I can drive a wonderful classic Caddy much more often.  My favorite daily driver was my 1995 Fleetwood RWD, drove it a quarter million miles with no issues - still looked great and had good power-amazing power (better than my 2006 Dodge Hemi).  I get a new sedan (two years old) every ten years whether I need one or not.

["Cadillac Kid" Greg Surfas 15364]

Scott,
These cars were made to be driven.  The quality that went into their engineering and construction allows for literally hundreds of thousands of carefree diriving if they are maintained properly.  I bought my '66 in 1993 and drove it as my daily driver to work and on trips for 20 years.  Everything was kept as close to original functionally as practical and felt at home in bumper to bumper daily commute traffic as well as 80 on the highway.
Greg Surfas

[TJ Hopland]

For identifying the sensors one thing would be the thread.  I believe the 472/500 era were 3/8-16?   The 4100 era ones I think were similar diameter but finer metric threads.   I will try to dig through my box and confirm this unless someone else knows for sure.

I have seen several colors.  That may have been a brand or factory difference. 

I know one way NOT to test them is with a propane torch.   Seemed like a good idea but hard to control.   About the time you get a reading the plastic starts to ooze out.    My new plan is to put them in an oven.   That should be fairly easy to evenly heat them to the various target temps and easy to read with an IR gun.  I was thinking of bolting them to a piece of metal so it will be easier to clip the ohm meter to them and it will also help them retain heat during the testing.

[George D. Mukalian CLC # 10047]

Greg:
The ones I have are from both a 1969 472 motor & a 1970 500 motor(eldo).
I just wanted to know what color was associated with what temperature.
I can't find any literature as to which colors went with which years & where
they went(Front head or Rear head).

George

["Cadillac Kid" Greg Surfas 15364]

George,
I do not believe "color coding" was anything intentional in these sensors.  The sensor that screws into the right head is for the "stop before the block melts" temperature warning light (not the water temperature light) and should "make the circuit at between 290 and 300 degrees F.  The sensor that is installed on the right cylinder head and located behind the alternator is the heater fan turn on switch.  It makes contact (to the ground) at between 75 and 120 degrees.  I have had the same part number sensors (D-1870) run that range of temperature.  It is not critical, and is an indicator that the engine coolant is warm enough to provide warm air if needed before it allows the fan to energize.
Greg Surfas

[Bob Hoffmann CLC#96]

Guys,
I looked at a pair of NOS ones. The RH front is red & has 120 stamped on the side.
The LH rear is gray & has 280 stamped on the side.
HTH, Bob

["Cadillac Kid" Greg Surfas 15364]

Bob,
Ive got 4 pair of NOS in front of me, and both sensors have similar  inscriptions to what you said, but ALL have bare aluminum bodies, black plastic inserts with white rings between the insert and the body (in the body cavity.  I don't believe the color coding was intentional, but a result of what the manifacturer used.  I bought these back in the '7os.
These sensors were made by several manufactures including AC Delco (mine), Standard, and others.
Greg Surfas