99 STS overheating prob, any help appreciated!

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03-11-2008, 04:23 AM

Caddyman77

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Join Date: Mar 2008

Posts: 2

99 STS overheating prob, any help appreciated!

First of all, thanks in advance to any replies or suggestions that any of you out there may leave, I'm really in a bind right now. I have a 99 STS with 115k, I've always driven her slow and steady, regular oil changes, up to date etc... All of a sudden my car started to overhead abruptly, the temp slowly climbed to the red end, but no steam was coming out of the engine. I obviously stoped the car, however it continued to overheat when I started her back up after ten min or so and even told me I had 0% engine oil even though I had just gotten an oil change a few weeks before this overheating madness occured.

Anyhow, took the car to midas but they said to take it to the dealer since the "service engine soon" light had also come on. The dealer did an inspection, replaced the temp guage, did TWO coolant flushes, and yet it's supposidly still overheating. Thus far the bill is around 450 for just the inspection, 2 coolant flushes, and temp guage. Seems kind of high but at this point since the engine is overheating on low range they told me that a gasket is blown, and said it will cost 4k to replace that or I can pay 5k for a new engine. After doing a lot of research on the net I've come across many people who blame the infamous gm recommended Dex-Cool coolant as the culprit of many ruined engines. Regardless of the dex cool implication, I'm thinking of just paying the 400 for the services up to this point and taking it to another dealership, or maybe just to a local mechanic that could possibily diagnose the problem for cheaper. And is 4k for replacing a gasket accurate? Or 5k for a new engine? I defineatly think I need to get a second opinion, part of me is paranoid that perhaps the temp thermostat was just stuck. Any advice would be GREATLY appreciated. I'm leaning toward taking the caddy to a smaller mechanic and paying another few hundred bucks to get a 2nd opinon before I either fix and replace the gasket or buy an entire new engine.

Thanks again for taking the time to read this and possibily give me any advice or comments!

03-11-2008, 06:27 PM

slowroll

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Join Date: Oct 2007

Location: in the mitten

Posts: 3,160

RE: 99 STS overheating prob, any help appreciated!

A CO test will tell you if head gasket is blown. There is a chance blown head gaskets will lead to engine replacement. The 4k head gaskets vs 5k for new engine is a bit confusing though.

03-12-2008, 02:52 AM

sls2001

Join Date: Feb 2008

Posts: 2

RE: 99 STS overheating prob, any help appreciated!

I have the same problem with my 2001 SLS. The temp quickly went from normal to the red after coming off the freeway and the change oil signal came on showing zero. The only coolant loss was a slight seepage and steam from the radiator fill cap. No water in engine oil. I am hoping the it is not a blown head gasket. I can let the car idle in the driveway and even drive it short distances without a overheating problem. I hope that someone can provide me with some advise as well.
Thank you in advance for your input.

03-12-2008, 12:52 PM

carnut

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Join Date: Feb 2008

Posts: 463

RE: 99 STS overheating prob, any help appreciated!

Any radiator shop can do a CO test. That checks for exhaust presence in the cooling system. A blown head gasket will generally idle for a long time before overheating because of the low friction at idle. More RPM, more friction or heat, thus overheats. Also are the radiator fans coming on? Is the purge hose to the recovery tank restricted, not allowing circulation? Is the radiator pressure cap holding correct pressure, has it been tested?

03-15-2008, 11:26 PM

rockfangd

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Join Date: Jan 2008

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Posts: 33

RE: 99 STS overheating prob, any help appreciated!

i have the same exact problem with my 96 eldorado 4.6. It runs beautiful and i can drive all over in the city, and it can run all day but when i drive it on the highway at about 55 for about 20 minutes it overheats but does not lose coolant. Im on the debate of either finding out what is wrong with it or selling it

04-11-2008, 07:16 PM

sls2001

Join Date: Feb 2008

Posts: 2

RE: 99 STS overheating prob, any help appreciated!

I have a similar problem with my 2001 SLS and there is no anti-freeze in the oil and after I drive for about 10 -12 miles under normal conditions, the tempgauge starts to creep up and then it will go all the way to hot. There is no leakage from the radiator cap or around the motor, but after I let it idle for about 5 - 10 minutes, the temp returns to normal range. I can drive it a few more miles and the same thing occurs. I have checked the heater hoses to see if one side is hotter than the other and both fans are coming on when the temp reaches a high reading. Ther doesn't appear to be any dirt blocking the radiator. I haven't changed the thermostat or had a CO test done as yet. Any other suggestions would be helpful.

Thanks
Bob

05-08-2008, 02:20 PM

stomper

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Join Date: Jun 2007

Posts: 2,701

RE: 99 STS overheating prob, any help appreciated!

Quote:

ORIGINAL: sls2001

I have a similar problem with my 2001 SLS and there is no anti-freeze in the oil and after I drive for about 10 -12 miles under normal conditions, the tempgauge starts to creep up and then it will go all the way to hot. There is no leakage from the radiator cap or around the motor, but after I let it idle for about 5 - 10 minutes, the temp returns to normal range. I can drive it a few more miles and the same thing occurs. I have checked the heater hoses to see if one side is hotter than the other and both fans are coming on when the temp reaches a high reading. Ther doesn't appear to be any dirt blocking the radiator. I haven't changed the thermostat or had a CO test done as yet. Any other suggestions would be helpful.

Thanks
Bob

we have a whole list of things one can do to test for exhaust gases in the coolant, in the FAQ section.
give it shot.