1997 Cadillac STS overheating

I have a 1997 Cadillac STS that has been giving me quite some trouble recently with the cooling system. First, I had a leak in the radiator, so I have put in a brand new radiator, thermostat and hoses (I figured
I would replace all those little things while Im at it)... I filled the system back up and it is now overheating, yet there is no visible leaks anywhere when I look all around the engine compartment (when the engine running or turned off) ... There IS definitely fluid going somewhere though, but it is not into the oil... I did an oil change as it was about due and there does not appear to be any coolant in the old oil. I thought maybe it was somehow leaking into the combustion chamber and getting burnned off like this, but I was told I would see a white smoke or steam from the tail pipes and I dont have this either... I am at a complete loss as to what might be going on.
Has anyone run into this before?
Thanks for any help in advance,
Kevin Lawrence snipped-for-privacy@rogers.com
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I don't have an answer, as such, but I have a question that might point you in the right direction.
On a system like that, where the pressure cap is on the overflow bottle instead of the top of the radiator, how does one go about getting the system FULL.......that is, get all of the air bled out?
I don't know the answer. If you don't either, I'm guessing you didn't get the system anywhere near full and the apparent loss of coolant is really just trapped air finally making it's way to the overflow bottle.
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Ken Abrams wrote:

Well, from what I was told, if you fill the system really slow, most of the air should work it's way up as you fill it up. Now, when I was filling it up, I only got two 3.78 litre bottles of fluid in there and the system is supposed to take over 11 litres... I thought perhaps there was just some fluid left in the engine that didn't get drained when I disconnected the hoses. Now that I think about it, 4 litres of fluid is a lot to be trapped in the engine when both hoses are disconnected, so perhaps there was a lot of air still trapped. I can't figure out where there is no air vent that I can use to let any air out... there is supposedly a hose that goes into the overflow bottle that is supposed to vent air, but it's not something I can open and close manually so its tough to control. Anyhow, maybe I will just keep filling it up for a bit and see if it stops going down. I will take the advice of another user who suggested running the car while parked on a steep hill, maybe this will help get air out.
Thanks very much! Will update if this works in case others run into this problem.
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Well, the caddy is no longer overheating, however in a 20-25 minute drive on the highway, to and from work each day is leaving me with about a 1 litre (1 quart) of coolant that is disappearing. I still dont see any signs of coolant leaking anywhere, and surely it can't just be air still working its way out... I have added more than the systems capacity since the original fill-up.
Any ideas as to where I would look for the possible cause of the coolant dropping like this?
Thanks Kevin
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wrote:

You have a few possibilities. Check the pressure cap and the line running to the coolant recovery tank. Pressurize the system and look for leaks. Finally, consider the possibility of head gasket failure. A leakdown test would confirm this.
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Merry Christmas Nicky:
I agree with you about the leak-down test. The dyed fluid shoud be able to substantiate the location of the leak. It is possible that a pin hole in one of the replaced hoses may be the source of the leak. That was the cause of the loss of coolant in from my 1995 STS. My technician located the source of the leak, and then replaced the faulty hose. Mission accomplished.
I hope that the head gasket is not the problem, since it is very expensive for a shop to repair, or labor intensive (sp) for Kevin and a buddy to replace.
Peace be with you during the holidays,
Famous
NickySantoro wrote:

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Merry Christmas Nicky:
I agree with you about the leak-down test. The dyed fluid shoud be able to substantiate the location of the leak. It is possible that a pin hole in one of the replaced hoses may be the source of the leak. That was the cause of the loss of coolant in from my 1995 STS. My technician located the source of the leak, and then replaced the faulty hose. Mission accomplished.
I hope that the head gasket is not the problem, since it is very expensive for a shop to repair, or labor intensive (sp) for Kevin and a buddy to replace.
Peace be with you during the holidays,
Famous
NickySantoro wrote:

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Hi, maybe, there is still some air in your system. put the car on a really steep slope with front side uphill (safety measures strongly recommended (;-), open the radiator cap, let the engine run, squeeze all the hoses, then fill in some more coolant. Should be OK then. Andreas
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Sinerviz wrote:

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Hello, I have a 97 Cadillac STS and I changed the water pump and the thermostate. I fill the car with coolant and I have the same problem its overheating. I have run the car with the termostate cap off to try to bleed off the air and still it overheats. Just wanted to know if you had any further info and did you fix the problem. Any advise would be great.
Sinerviz wrote:

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Hi I also had a problem with my 1997 Eldorado Touring Coupe and it was heating up when going fast but not going slow. So I took it in and they said that I had a this that and everything else that you could think of,it cost me over $2000.00 dollars and it still over heated so then they said it was a head gasket and it would cost $4000.00 dollars to do both heads to play on the safe side. I thought that was to much and found a retired mechanic who did it plus a few other items for $2000.00 dollars but know it drives perfect at high speeds and just goes over a pinch in the middle of the heat guage needle,is that alright? Or should it be the same? Could it be a air lock in the system or could it be the thermostat is sticking a bit,heat valve,or clogged a bit?? please let me know and thank you!
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tm>Hi I also had a problem with my 1997 Eldorado Touring Coupe and it was tm>heating up when going fast but not going slow. So I took it in and they tm>said that I had a this that and everything else that you could think of,it tm>cost me over $2000.00 dollars and it still over heated so then they said it tm>was a head gasket and it would cost $4000.00 dollars to do both heads to tm>play on the safe side. I thought that was to much and found a retired tm>mechanic who did it plus a few other items for $2000.00 dollars but know tm>it drives perfect at high speeds and just goes over a pinch in the middle tm>of the heat guage needle,is that alright? Or should it be the same? Could tm>it be a air lock in the system or could it be the thermostat is sticking a tm>bit,heat valve,or clogged a bit?? please let me know and thank you! tm>
The analog gage is fine but you don't see numbers.
You can monitor the coolant temperature on the DIC. Cycle thru it with the Info button, it should be right after Battery Volts. It is not programmed by the factory to show this info, though. Here is how, using your HVAC panel:
Yes = |Fan Up| No = |Fan Down|
Ignition key in "Run" (engine may or may not run).
Hold |Off| & |Pass Warmer| simultaneously to start Diag mode. Everything lights up on the IPC, then diag codes are rolling. You may want to jot down the codes, but they are irrelevant for our purpose. After going thru all codes, you'll get a prompt:
Prompt            Answer
PCM?            No IPC?         Yes    <==IPC DATA?        No IPC INPUT?        No IPC OVERRIDE?        Yes    <==IPCS13        86    No IPCS12        77    No IPCS11        0    No IPCS10        99    No IPCS09        0    No IPCS08        73    No IPCS07        73    No IPCS06        0    No IPCS05        43    <==== At this point, with the |Pass. Warmer| button                 change this number to 111. Save this value by pressing and holding the |Front Defrost| and |AC| buttons simultaneously until the number 111 on your DIC blinks once. Then enter "No" (Fan Down). Answer with "No" to all remaining prompts, and exit diag mod by pushing in the big |Auto/Temp| Dial or turning off the ignition.
Note: The IPCS** values appear in the trip odometer display. Another note: By changing the "IPCS03 160" to 132 (w/ the |Pass. Cooler| button, you can get rid of the Daylight Running Light "feature".
WARNING!!! Do not do it if you are not sure you *can* do it. If you screw up, the IPC must be replaced. If you've started the process, and think you've made a mistake or you want to abort it, hit the |Off| button, answer "Yes" to the IPC CLEAR CODES? prompt, exit diagnostics and start over.
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Thanks for the info!!!!!
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