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Water temp idiot light

Started by Jeff Rosansky CLC #28373, June 09, 2015, 10:28:52 PM

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Jeff Rosansky CLC #28373

70 Deville
What temperature does the Water Temp idiot light kick on?
Just shy of a hundo here today.  Stuck in traffic for a while with the a/c on.  Idiot light kicked on.  Pulled over and opened the hood. Lot of bubbling in the overflow tank but didn't overflow.  Let her cool for about 15 minutes and drove her home.
What temp does the light come on, and what temp should we be concerned about..... In other words, shut her down immediately when the light comes on or OK to drive a bit. I was less than a mile from home.
Thanks
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

chrisntam

#1
I seem to recall water temp sender was around 260 degrees, the engine temp light comes on at 320?  295?

Was driving mine this weekend (low 90s) and the engine temp (metal) was around 220 to 240.  After I shut it off, restarted it about 5 minutes later, the metal temp was up to 250 (as it should be).  After starting it, it took a good minute or two of the water circulating to get the metal temp back around 220.

Others have said it being a new engine and being tight is creating extra friction (heat) I have about 250 miles on it.  I plan on pulling the 195 stat and putting in a 180.  I already have a new 4 core radiator with a 7 blade fan.  I also plan on putting a water temp gauge on it at the same time, just so I can see what the water temp is.  I just need a better judge of what is really going on with the engine (temp wise) than just having the metal temp gauge on it.  I think mine is running hot, but I can't really tell yet (mine has never bubbled in the overflow tank).

Suggest to put some gauges on it so you can keep an eye on what is actually going on.

chris.
1970 Deville Convertible 
Dallas, Texas

chrisntam

Took a quick look at the FSM, it says the idiot light and engine temp lights come on when their temperatures are "excessive".  That sure helps............

Still looking...........
1970 Deville Convertible 
Dallas, Texas

bcroe

Quote from: chrisntam on June 09, 2015, 11:04:26 PM
Took a quick look at the FSM, it says the idiot light and engine temp lights come on when their temperatures are "excessive".  That sure helps............          Still looking...........         

I don't like being "surprised" by a light coming on, at an unknown temp at that.  And I don't like not
knowing if I am continuing to make the condition better, or the same, or worse.  The answer, as advised
above, is a legitimate temperature gauge; I add one to every vehicle that doesn't already have one. 

I like the bulb type, which work even with engine off.  The 270 degree scale ones are quite compact.  Bruce Roe

Scot Minesinger

I am in the same boat as Chris:  Rebuilt engine, 4 row radiator, 7 blade fan (from commercial chassis), and temperature gauge. 

The 4 row radiator required that I add rubber between side tanks and fan shroud to keep air flowing thru radiator instead of around it.  Make sure there is not an air path of less resistance around your radiator instead of through it.

My re-built engine is bored 0.030 inches over, which makes a 472 a 478 engine and the thinner walls between coolant and combustion chamber is actually what makes the car run slightly hotter, not more friction internally.

Generally my car is not running in much hotter weather than 95'F to 100'F, but with top down and a/c off.  If I get caught in rain, of course the top is up and a/c on.  I have stress tested the car by having it in a/c and 95-100'F with top up and it runs at 220'F when idling for extended periods.  Make sure timing is set per factory specs, it makes a big difference at idle if it is not set right.  Make sure idle speed is set correctly to  the factory spec (set with car in drive, foot on brake, and a/c on high).

I think that the temp light controlled by sensor under a/c compressor (coolant) is set at 260'F and the hot block sensor is past 300'F.  I used the coolant sensor port for my temperature gauge.  Attached is my gauge set up.  Try not to get too much of a temperature gauge watcher.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Jeff Rosansky CLC #28373

Yah. The manual does not give a spec that I was able to see. I looked at aftermarket ones on line thru NAPA,etc but did not find a spec there either.
Mine is .30 over too and a new engine. Did not lose any coolant. It was in traffic for a while, got on the hiway for about 2 miles and then traffic again for about 20 minutes. I have a gauge but not installed yet. When i get it in, what temp is too hot? What is my "shut it down now" tsmp?
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Jeff Rosansky CLC #28373

Actually, now that I think about it, I wonder if the fan is on correctly. Could someone post a quick picture please?? I know I had it on correctly, but as some may remember the engine bjilder screwed up and a shop had to repaie it. Wonder if it is backwards. I know it is marked but I can't easily see it.

Scot, could you ease post or pm me a licture/ info on that extra baffling you were talking about?  The radiator could probably use a good cleanout but can't spend the $$ rite now.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

chrisntam

IIRC, the blades should curve towards the engine.  I doubt it is on backwards, don't think there would be enough clearance between the radiator and a backwards fan.  Don't have mine to look at right now............

I too would like a pic of Scots shroud work!
1970 Deville Convertible 
Dallas, Texas

Scot Minesinger

Here is a picture of the fan and how it should look.  This is a 5 blade on a 1970 Cadillac SDV.  The fan has a clear stamp on it labeled "FRONT".  Anyway if your fan was installed backwards it would overheat if it was much over 80'F as air would be drawn out of the engine bay and air flow would be nil when traveling at speed because of headwind, so I doubt it is in backwards.

Also is the picture where I sealed off the sides with rubber-look close at edge of radiator and sides against shroud.  Also the rubber sheet under radiator (not pictured) is important too.  My car ran hot without the rubber sheet.

The cooling systems on the 71 - 76 Cadillacs seems more robust than the 68-70 Cadillacs, and that may have developed out of problems you just suffered.  The radiators are larger and the fans are better than the 68-70 Cadillacs it seems.  About the only thing you can do is go to the 7 blade fan to retain a stock look.  The 69 Cadillacs used a fan clutch, so the 7 blade commercial chassis fans may be in demand, get one now at Cadillac King, Cadillacs Only or etc.

if ever you in an overheat situation again, turn a/c off that makes the car run about 5'F cooler.  If that does not suffice and you need to get home, put vacuum on power servo and car will go into heat mode and then runs another 8'F cooler.  Driving in 100'F plus with a/c off, windows down, and heat on is a health risk.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

"Cadillac Kid" Greg Surfas 15364

Jeff,
To put numbers to the lights, the "water" light comes on when the coolant temperature reaches 264 degrees, and the engine temperature light is 295-320 degrees. Cadillacs run hot, and that is the reason for them utilizing the thermal vacuum switch to switch from a ported vacuum to a direct manifold vacuum signal to the distributor when the motor reaches 230 degrees, a very, very, very common occurrence in Summertime traffic.
If you are in an area where the temperature is in the century range, like we are here in Southern Texas, the only way to maintain acceptable temperatures (motor) is with a 7 bladed (AC option) fan, a 4 row (2-5/8" thick) core radiator, correct timing, working vacuum advance and either direct manifold vacuum to the vacuum advance or a functional thermal vacuum switch.
As far as what to do when the light comes on, what I found (120 degrees in the Palm Springs desert) was to somehow get moving so enough air would get through the radiator and in a minute or two, the light would flicker and then go off.
Sometimes easier said than done.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Jeff Rosansky CLC #28373

Yws. Just was not ablento get moving again or I am sure the lifht would have gone off. I'll just throw a cattleguard on ths front next time I have to drive in traffic!!
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

"Cadillac Kid" Greg Surfas 15364

Jeff,
In a brand new Eldo (everything was "perfect" I had to just go in a direction that would let me get some air a couple of times.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Scot Minesinger

The 72 Eldo has a little better cooling system (better fan) than the 70 Cadillac.  The replacement 4 row radiator is same by USA Parts for either a Cadillac 70 RWD or 72 Eldo.  I'm in the testing/commissioning stage of a 72 Eldorado and so far we have not been above 90'F so even with top down and a/c on it is running well. 
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

"Cadillac Kid" Greg Surfas 15364

Quote from: Scot Minesinger on June 10, 2015, 01:29:30 PM
The 72 Eldo has a little better cooling system (better fan) than the 70 Cadillac. 
And you figure that how?
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Gene Beaird

Quote from: "Cadillac Kid"  Greg Surfas 15364 on June 10, 2015, 11:41:25 AM
Jeff,
To put numbers to the lights, the "water" light comes on when the coolant temperature reaches 264 degrees, and the engine temperature light is 295-320 degrees. Cadillacs run hot, and that is the reason for them utilizing the thermal vacuum switch to switch from a ported vacuum to a direct manifold vacuum signal to the distributor when the motor reaches 230 degrees, a very, very, very common occurrence in Summertime traffic.
If you are in an area where the temperature is in the century range, like we are here in Southern Texas, the only way to maintain acceptable temperatures (motor) is with a 7 bladed (AC option) fan, a 4 row (2-5/8" thick) core radiator, correct timing, working vacuum advance and either direct manifold vacuum to the vacuum advance or a functional thermal vacuum switch.
As far as what to do when the light comes on, what I found (120 degrees in the Palm Springs desert) was to somehow get moving so enough air would get through the radiator and in a minute or two, the light would flicker and then go off.
Sometimes easier said than done.
Greg Surfas

Man, are you sure of those temps?  Because at about 365 deg. F, the babbitt on the bearings starts getting soft enough to come off.  320-deg. F water temp is going to make for a pretty hot engine block.   :o
Gene Beaird,
1968 Calais
1979 Seville
Pearland, Texas
CLC Member No. 29873

gary griffin

#15
If a blade could go on  backwards the pitch would still be the same. 

Increasing pressure raises boiling point. A 15 PSI pressure cap for example raises the boiling point to 257 Degrees Fahrenheit. The advantage of that is, if the air temperature is 100 degrees there will be a temperature differential of 157 degrees between the cooling air and the boiling point. There would be a little fluid going to the recovery tank due to normal expansion but there should be no boiling in the expansion tank.

Boiling at 300 degrees would require a 51 PSI radiator cap as 300 degrees creates a pressure of 66 PSIA (Absolute pressure less 15 degrees atmospheric pressure.) (Rounded to whole PSI)

If I had the rating of the pressure cap I would know the temperature to boil but I doubt a normal car would have a 51 PSI radiator cap.

I have an inexpensive thermometer that takes surface temperature by pointing it at the object. It would be handy in figuring the set points for aptly named "Idiot Lights".  I always wondered why the auto industry thought we wanted less information about our car engines rather than more information. I like oil pressure in PSI and engine temperature in Degrees Fahrenheit. I like the transmission temperature gauge in my truck also for example. Having been a pilot for many years I am accustomed to a lot of needles and dials.
Gary Griffin

1940 LaSalle 5029 4 door convertible sedan
1942 Cadillac 6719 restoration almost complete?
1957 Cadillac 60-special (Needs a little TLC)
2013 Cadillac XTS daily driver

"Cadillac Kid" Greg Surfas 15364

Gene,
That 295-320 (different sensors were used ) is cylinder head metal temperature.  Metal temperature is higher than the water temperature in the engine, and the limit would be reached almost immediately if the coolant was lost.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Jeff Rosansky CLC #28373

Needles give you something to watch. Without them, all I have to do while driving is text :)
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Jeff Rosansky CLC #28373

Kind of glad nobody out there really knows me because I seem to admit STUPID on this site an awful lot.
Of all the things that I replaced when I did the engine, I never replaced the cap.  Just looked at it, and it's a 7lb cap..... Not 15-16.  Oh well, It made for a good discussion anyway.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Scot Minesinger

Greg,

The 72 Eldorado had a better fan than the 1970 standard 5 blade fan.  Radiators and water pumps were apparently identical.  I think that with the 7 blade commercial chassis 1970 fan they are real close.

Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty