: 97' DeVille Northstar overheating



newtogolf
06-18-05, 01:44 PM
A couple of days ago my cadillac overheated to 260*. I am replacing the thermostat today. I noticed that only one radiator fan (drivers side) is coming on while the A/C is on (only drove is for 10 minutes today). Is that normal or could something be wrong?

newtogolf
06-18-05, 03:53 PM
Ok...I am stupid! How do you change the thermostat on a 97' Cadillac DeVille? Where the heck is it?

Ranger
06-18-05, 06:04 PM
Follow the upper radiator hose from the radiator to the engine. You'll find it there. I think both fans should be on with the A/C if I am not mistaken.

b4oliver
07-04-05, 04:13 AM
The thermostat is located in the water pump housing cover where the lower hose connects.

daemart
07-04-05, 10:50 AM
Your thermostat is not the problem. We always blame the thermostat because it's easy. Most likely you have a leak in your radiator tank on the right side of the car. Your radiator tank is the plastic end of the radiator on both sides. These things develop a crack when your temp gets that high. It's the right side tank that always blows first because that's where the hot coolant first enters the radiator. See if you can see any coolant leaking out. Find a cheap radiator shop and have a pressure check done.
Most of the time, both fans come on at the same time -- that's what your center relay is for. The three relays are located behind and at the bottom of the radiator. Unplug your bad fan and hook 12 volts to it - at the fan side, not the relay side. If it doesn't turn, you have a bad fan. But you probably have a coolant leak also.

Don

Ranger
07-04-05, 09:58 PM
The thermostat is located in the water pump housing cover where the lower hose connects.
OOPS :o

psychosis
07-10-05, 02:44 PM
On my 96 Deville I changed the radiator two weeks ago after detecting a leak (yes...on the right side just as was mentioned).

The "low coolant level" message came on which is why I looked to find the leak. Now two weeks later with the new radiator, hoses, sealant, and some "Kool It" conditioner started running hot today. The little red thermometer light came on so when I checked the information center for the coolant temp it was running about 250 degrees! All the way way home if fluctuated between 225 and 250 degrees. When moving it cools back down to 230 or so. But sitting in traffic climbs right back to 250 quickly.

Seems too hot to me buts it also seems to be running OK. Does anyone know what is the "normal" coolant operating temp for a Northstar on a warm (90) florida rainey day with the AC on? I was thinking maybe a water pump? Fan not coming on? It just turned 50 thousand miles.

Thanks in advance.......

Geno Castellano
07-10-05, 10:59 PM
On my 96 Deville I changed the radiator two weeks ago after detecting a leak (yes...on the right side just as was mentioned).

The "low coolant level" message came on which is why I looked to find the leak. Now two weeks later with the new radiator, hoses, sealant, and some "Kool It" conditioner started running hot today. The little red thermometer light came on so when I checked the information center for the coolant temp it was running about 250 degrees! All the way way home if fluctuated between 225 and 250 degrees. When moving it cools back down to 230 or so. But sitting in traffic climbs right back to 250 quickly.

Seems too hot to me buts it also seems to be running OK. Does anyone know what is the "normal" coolant operating temp for a Northstar on a warm (90) florida rainey day with the AC on? I was thinking maybe a water pump? Fan not coming on? It just turned 50 thousand miles.

Thanks in advance.......


250 and the coolant temp warning is too hot. You have a problem of some sort. The most obvious answer is the one you mentioned. The engine's electric cooling fans are not working. If the engine gets that hot at idle when there is little to no load on it (but no ram air flow through the grill) and yet cools down fine when the car is moving (causing ram air thru the radiator) then the engine cooling fan operation is very suspect.

Idle the car with the AC on and pop the hood and look at the fans. They should be running with the AC on as the AC condensor requires air flow all the time even if the engine is relatively cool. Most anytime the engine is idling with the AC on the fans should be running. If not, start by checking fuses and relays in the relay center. You may have a shorted out fan motor or something like that.

libilibi
07-10-05, 11:30 PM
hi my name is Karim and i am a car salesman

I recently purchased a 1997 Caddy Deville D'elegance from the auction, the car is having overheating problems and i cant figure out what it could be,
here are the things i've done so far:

Flushed the radiator

changed the thermostat

changed the water pump

checked the purdge line and it was fine, it had flow

engine fans work great, low speed and high speed

radiator has no cracks

and the car is not consuming coolant nor is it mixing with oil.

Any ideas of what it could possibly be??

Ranger
07-11-05, 11:18 AM
Have you pressure tested or replaced the pressure cap on the surge tank?

johnito1
07-11-05, 08:49 PM
I have a 1994 Concour that is overheating. I have bought a new water pump, radiator, hoses, belts, etc. But it is still overheating. There is no oil in the water, but I'm being told that the heads are warped and that there is no way of having them rebuilt...valve job! Need some advise.....Anybody...help..pls???

Ranger
07-11-05, 09:23 PM
Northstars are not likely to get coolant in the oil if a head gasket blows. Just the nature of the beast. Check the belt tensioner and the purge line. If all is well then pressure test each cylinder to confirm the head gaket.

Geno Castellano
07-12-05, 12:52 PM
I have a 1994 Concour that is overheating. I have bought a new water pump, radiator, hoses, belts, etc. But it is still overheating. There is no oil in the water, but I'm being told that the heads are warped and that there is no way of having them rebuilt...valve job! Need some advise.....Anybody...help..pls???


It may be a head gasket but the idea of "warped heads" and such is incorrect. It just doesn't happen. If you read through past posts there are many examples of the heads coming off for head gaskets with way way over 150K miles on them and the heads are fine as are the valves and there is no need for a valve job... It's really a thing of the past.

johnito1
07-12-05, 08:31 PM
Thanks for the advice. Does anyone know the process for completing a pressure test on the cylinders to confirm if head gasket is blown. If blown...are the heads repairable?

Geno Castellano
07-13-05, 12:26 AM
Thanks for the advice. Does anyone know the process for completing a pressure test on the cylinders to confirm if head gasket is blown. If blown...are the heads repairable?


This has been described many times in past posts. Do a forum search using "cylinder pressure test" and it will likely show up in the results.

Posts like this have the procedure: http://www.cadillacforums.com/forums/showthread.php?t=44107&highlight=cylinder+pressure+test

psychosis
07-15-05, 09:32 AM
OK, My "In Denial" phase is over.

(1) Installed the new GM radiator on my 96 DeVille to fix a broken side tank along with new hoses, clamps, sealant pellets, and "Kool it" conditioner. Nothing but the best for my caddy but now what?.......now its overheating?

(2) I'm sure it has to be the thermostat. Theres no way it could be the dreaded head gasket leak. Its only got fifty thousand miles. Besides I wax it every weekend with the best stuff I can buy and keep it stored away in my garage all week under the latest high tech car cover.

(3) Changed out that Thermostat and its still overheating? I was still holding out hope that the water pump was failing.

(4) Checked out the waterpump and its fine? Still in denial, I'm imagining a still have a leak somewhere else and thats why my purge talk is always empty. Bar's leak sealer should fix that!

(5) Still overheating? No it couldn't possible be........OK OK i'll check to see if I'm getting combustion presure on the system.

Damn! Head the gasket is leaking. I guess knew it all along.

Wait a minute........before she goes to the salvage yard....... is there something else I can try to save her....? Thanks

PT

zonie77
07-15-05, 01:23 PM
If you don't want to do the head gaskets put it up for sale at the value the salvage yard/car dealer will give you. Someone on the forums may be willing to buy it.

Update the thread if you put it in the ad section.

mcowden
07-15-05, 03:04 PM
OK, My "In Denial" phase is over.

(1) Installed the new GM radiator on my 96 DeVille to fix a broken side tank along with new hoses, clamps, sealant pellets, and "Kool it" conditioner. Nothing but the best for my caddy but now what?.......now its overheating?

(2) I'm sure it has to be the thermostat. Theres no way it could be the dreaded head gasket leak. Its only got fifty thousand miles. Besides I wax it every weekend with the best stuff I can buy and keep it stored away in my garage all week under the latest high tech car cover.

(3) Changed out that Thermostat and its still overheating? I was still holding out hope that the water pump was failing.

(4) Checked out the waterpump and its fine? Still in denial, I'm imagining a still have a leak somewhere else and thats why my purge talk is always empty. Bar's leak sealer should fix that!

(5) Still overheating? No it couldn't possible be........OK OK i'll check to see if I'm getting combustion presure on the system.

Damn! Head the gasket is leaking. I guess knew it all along.

Wait a minute........before she goes to the salvage yard....... is there something else I can try to save her....? Thanks

PT


What about the cap? Did you replace the cap on the surge tank? It's 15 pounds, not 16, not 13. 15 pound cap. For $3-$5 it's a cheap and easy fix before you jump to conclusions.

weister42
07-16-05, 11:49 PM
my coolant is not leaking, but the transmission oil line going into the radiator is seeping:( I'm gonna order a radiator soon

Riceless
07-18-05, 08:25 PM
Im havin a problem too, overheating, runs fine, no smoke, fans coming on, just put a thermostat in and flushed the radiatior, still overheating. Only 70,000 on a 97 Northstar. I think its time for a recall. This is horse shit. I think some antifreeze comes out the overflow tube... It would have been very nice of Cadillac to put a damn fill to line somewhere on the damn tank... Maybe it has something to do with that cap, I guess Ill go get a new one and try it. Its gotta be something weird like that... If it dosent fix it, then while I got the radiatior cap off Ill drive another car under it and call it fixed.

BeelzeBob
07-18-05, 09:37 PM
Im havin a problem too, overheating, runs fine, no smoke, fans coming on, just put a thermostat in and flushed the radiatior, still overheating. Only 70,000 on a 97 Northstar. I think its time for a recall. This is horse shit. I think some antifreeze comes out the overflow tube... It would have been very nice of Cadillac to put a damn fill to line somewhere on the damn tank... Maybe it has something to do with that cap, I guess Ill go get a new one and try it. Its gotta be something weird like that... If it dosent fix it, then while I got the radiatior cap off Ill drive another car under it and call it fixed.



Just take the pressure cap off when the system is cold and the coolant should be about 1.5 to 2 inches from the cap fitting. Not that hard.

Check the coolant level when the system is cold each morning and see if it is dropping. One clue would be if the system is loosing coolant or not.

Have you checked all the other things mentioned in other posts on overheating..??? such as the water pump drive/belt/tensioner and the flow of coolant thru the vapor vent line to the surge tank...???

Eldorado Pimp
07-26-05, 01:42 AM
Okay guys I have a 93 Eldorado with overheating problems, Tried changing the themostat. Flushing the engine and putting in straight dex cool. Can you do that? or does it have to be pre-mixed. Will try new radiator cap next. Keep your fingers crossed.

Ranger
07-26-05, 11:32 AM
DO NOT use straight Dex. Mix it 50/50.

zonie77
07-26-05, 07:52 PM
You can use straight coolant but it isn't as efficient as a 50/50 mix. Water is a much better coolant than ethylene glycol but it rusts/corrodes the cooling system and freezes/boils easier than ethylene glycol. Ethylene glycol by itself isn't as good a coolant (heat transfer lower).

It is MUCH better to use the recommended mix.

You don't need the premixed. Use distilled water to make it 50/50. Preferabley mix it before you pour it. That way you don't get surprised when it fills and you are almost a gallon short of one of them.

mcowden
07-26-05, 08:35 PM
DO NOT use straight Dex-Cool. Mix it 50/50 with distilled water, just like it says to do on the bottle and in your car's manual. You risk serious engine and cooling system damage running straight coolant of the orange or green varieties. :bonkers:

If you've already put straight Dex-Cool in there and driven it, you'll have to drain it and dump in a mostly distilled water mix, then run it up to temp and test the concentration after it's cooled. Adjust as required until you get the right numbers. The float-type testers are not always accurate, so you may need to borrow a refractometer type or take it somewhere that has one. If you dumped in straight Dex-Cool but have NOT started it yet, drain it back out and refill with a 50/50 mix of Dex-Cool and distilled water.

In any case, don't forget to include the 6 supplement pellets or 2 tubes of Bar's Leaks Golden Seal powder. Avoid the other supplements, no matter how tempting or more compatible they seem. The GM or Bar's Leaks powder supplements are the ones recommended by GM and the only ones you should use.

zonie77
07-26-05, 09:20 PM
I should have been a little stronger about that. Your car can run on straight coolant but it is more likely to overheat. It is definitely NOT recommended. I am NOT recommending it. It could be done in an emergency but not in normal use.

Ranger
07-26-05, 09:49 PM
Dex-Cool is acid based. 100% Dex is not a good idea at all. Infact I would say it is not even an option.

oldgamer
07-27-05, 03:31 PM
... I'm sure it has to be the thermostat. Theres no way it could be the dreaded head gasket leak. Its only got fifty thousand miles. Besides I wax it every weekend with the best stuff I can buy and keep it stored away in my garage all week under the latest high tech car cover...

psychosis,
you're joking, right?
Never heard waxing and storing in a garage can prevent a head gasket leak :D
Sorry to hear about that overheating problem, though.
I store my car in a garage and wax it too and now transaxle's broken.:( Never gonna wash it again :D :D :D

psychosis
07-28-05, 11:52 AM
Just Kidding! I wish waxing it and keeping it in the garage would fix everything! Actually before she went to the junk yard I got lucky and was told about a guy who owns a small Auto AirCond shop in the city who knows these cadillacs inside and out, backwards and frontwards. Hes the man....

So this is how it went down to fix it.....

- Normal Operating range between 218 -228 degrees
- Seems a little hot but it seems OK
- Opps..No what? Coolant low message comes on
- Check Coolant level, Low Coolant in the surge tank no big deal. right?
- Drive for a day, Coolant level lights on again?
- Pressure test system, Major Radiator Leak in side tank
- Replace Radiator, Hoses, Cap, Coolant, water wetter, Barrs Gold Seal
- Ok for about a week
- Darn.....Overheat idiot light comes on 250+ degrees and staying there
- Now what, no more leaks..it must be Head gaskets! Damn......

Finally found the "Cadillac Man" ..they say hes been working on Cadillacs since the 50s ....he'll know what to do.

- Dye agent in the Radiator to check it for combustion system leaks
- Run it around for about an hour.....Nothing! No combustion gas detected!
- Have you Checked Water Pump? - its Ok but if that seal (o-ring) is weeping!
- Possible Air Bubble/Loss of Coolant due to water pump seal leak by.
- Replace Water pump, seal, belts

-Now its running between 196 and 208 all day long in 105 degree weather and in traffic...3 weeks now running every day and no more problems!:worship:

If everything else seems ok ....BEFORE YOU TEAR IT DOWN... CHECK THAT WATER PUMP! Even a slight leak in the O-ring around those water pumps can cause an overheat condition on a Northstar due to air getting into the system. (So sayth the Cadillac Man)

oldgamer
07-28-05, 12:40 PM
That sounds better!

mexakin_22996
08-03-05, 09:15 PM
i have a 96 deville, its overheating but the weird thing is that it only does it on the high way, i checked the radiator,new thermostat,all hoses, heatercore, pressure tested it and no leaks,and took the waterpump cover off and seemed to be workin fine nothing broke both sides turned ok, when it gets hot i just lets the water out the drain hose by the radiator cap, yesterday when testdriving when i got to like 55 i heard a belt screach, might b the water pump i dont know. any suggestions please,,

oldgamer
08-03-05, 09:56 PM
Check the water belt too.

zonie77
08-05-05, 03:31 PM
If it's headgaskets they may only show up at higher speeds or uphill, of course that's true of other problems too. Check the other stuff first though and make sure it's not a bad radiator, etc.

chevyorange
08-05-05, 06:16 PM
If you are getting the higher temps during bursts of full throttle (especially uphill) otherwise it drives fine, it sounds like my car which was head gaskets/crack in one head... and I've read of others with the head gasket problems all seem to have overheating and loss of coolant after an uphill drive/acceleration yet drives fine around town.

erroneous
08-05-05, 11:36 PM
When you say higher temps uphill, how high? Because my 96 Deville goes up to 233 after coming off the hiway and going up a mountain. Usually comes down pretty quick but right after that i get oil press idiot lite at idle speeds. Which rotella mostly cured!

zonie77
08-06-05, 02:18 AM
If you aren't losing coolant your headgaskets are fine.

Mysterious loss of coolant is another sign.

chevyorange
08-06-05, 02:23 AM
I'm talking 250 - 260 going uphill, with coolant loss. Don't even waste your time checking anything else if you have these two symptoms, from my research.

zonie77
08-06-05, 03:20 AM
chevyorange,

remember someone came on with a bunch of symptoms and 3 people (incl me) said sounds like head gaskets. There was a ration of s*** about it turning out to not be head gaskets! I think it was a bad radiator. I'm just being cautious, but you are right!

erroneous
08-06-05, 09:49 AM
Thanks guys

The more I read here, the better I feel.

It seems, imho, that even experienced GM mechanics have problems diagnosing the N* powered vehicles. Here, we have real experiences and real-world solutions to our perplexing problems.....
This is one the best forums I have ever seen, and thats due to people just wanting to share their unbiased info. The way it SHOULD be. :worship:

zonie77
08-06-05, 12:01 PM
When the head gaskets first start to go the symptoms are subtle and hard to diagnose. The first one I saw with bad gaskets kept me trying to fix an overheating problem because it ran so well. Plus it only overheated occassionally. Eventually it got bad enough to show on a compression test. Even then it wasn't real low. Mysterious loss of coolant is the usual key.

mexakin_22996
08-06-05, 03:15 PM
ok i just did a complete flush on the system today, yesterday new radiator, and the day before new water pump today i drove it around town for like 1 1/2 hours and fine even with the ac on just whent out of town and it overheated, what the hell is goin on.???? im gona buy a new radiator cap right now see if it does anything, the only thing i can think of is the belt tensioner being bad any sugestions, i dont think its the heads cuz like 3 months ago i did a valve job on it, well hope its not that anyway.

mexakin_22996
08-06-05, 03:38 PM
anyone that can help me out can you send me a phone # so i can talk to u and see if u can help me out if u dont wanna post ur # here email me at ramo_22996@hotmail.com thanks i would really apreciate it

zonie77
08-06-05, 04:59 PM
What was the reason you did a valve job?

Did you timesert the block? Did you replace all the head bolts?

If you drive it in town and then check the coolant, is it low? Does it mysteriously lose coolant without overheating?

I would try a compression test on it and see if any cyls are low. A cyl leakdown test is better, more accurate. If possible do that.

mexakin_22996
08-06-05, 05:52 PM
i did the valve job because i took the motor out to fix the oil leak, and i did time sert the block, every single hole, and new headbolts and gm headgaskets. i havent checked if it looses coolant in town, i just put a new radiator cap in a little bit ago and it still overheated, and it is just when i hit like 45 and stay at 45 the temp goes all the way up to 255or 260 if y keep it at 45 or more.

mexakin_22996
08-06-05, 05:54 PM
is it possible that when i put the new waterpump in, the seal might b leakin air into the system, to make the waterpump snap in to were it suposed to be i had to use a cheater bar on the handle of the ratchet, it did go in kinda hard but i dont know if thats how its supposed to be.

zonie77
08-06-05, 07:21 PM
The water pump is hard to install. If it was leaking air it would also be leaking water.

The Caddy heads usually do not warp but maybe yours did. Did you check them or have a shop check them for warpage?

If the checked OK I would repeat what I said about doing the cyl leakdown test.

Plus, check the coolant after driving.

Cracks are also unusual but a possibility.

I think You'll have to start from scratch. Forget everthing you did and start rechecking. I know it's a pain but after all that work you want it to run good.

b4oliver
08-07-05, 01:33 PM
Where is this Cadillac Man located so that others may go to him for help? Thanks.

mexakin_22996
08-09-05, 08:33 PM
anyone interested in buying my car for 3000, everything is perfects except the overheating problem im having, its pearl white. good paint, email me at ramo_22996@hotmail.com for more info...

paintedalley
11-20-05, 03:20 PM
What about the cap? Did you replace the cap on the surge tank? It's 15 pounds, not 16, not 13. 15 pound cap. For $3-$5 it's a cheap and easy fix before you jump to conclusions.

Can you tell me what the difference it will make to use a 16 pound and not a 15 pound? my 98 deville uses a 15 lb cap, I had a new thermostat put on and a new cap..a 16 lb was put on because thats what the book said my car used... it HAD a 15 pound on there... will it run hotter? perform worse? damage my system?
Thanks!

mcowden
11-20-05, 04:26 PM
Can you tell me what the difference it will make to use a 16 pound and not a 15 pound? my 98 deville uses a 15 lb cap, I had a new thermostat put on and a new cap..a 16 lb was put on because thats what the book said my car used... it HAD a 15 pound on there... will it run hotter? perform worse? damage my system?
Thanks!

It's probably not a huge problem, but I would still put a 15 pound cap on it. The cooling system components were designed to hold 15 pounds of pressure and the higher rated cap is putting more strain on them than they were designed for. One pound is not a great big deal, but for $3-5, it's very cheap insurance.

Ranger
11-20-05, 06:48 PM
As Micheal said, it won't do any harm. It just means that the system won't vent excess pressure til 16 vs 15 lbs and will raise the boiling point by about 3 degrees.

paintedalley
11-22-05, 12:32 AM
Thanks to you both for the fast reply!