Thread: Frustrating and confusing overheating / hot condition

Hi Everyone,

First post here as I'm a new member. I've searched through the threads and can't find anything similar to what has been happening with my car so I thought I would start a new thread and ask for your input / advice. My car is a 1998 3.1 SE with 240,000kms, automatic transmission. I'll try to be as brief and concise as possible,

I've owned the car for 2.5 years it ran beautifully for the first year, the temp guage read consistently 83*C, then it developed a leak and the low coolant light was on, turned out it was the water pump which I replaced, everything back to normal (no light, no leaking).....jump ahead 1 year to about 3 months ago, coolant light back on, loosing coolant and car was overheating due to major coolant loss. Took the car in and the shop advised that the timing chain cover gasket was leaking. I could see coolant dripping off of a hose near that area so it made sense. I replaced the timing chain cover gasket and there hasn't been any leaks. However, the low coolant light has stayed on ever since the gasket was replaced. I replaced the radiator cap after the gasket change as the old one looked pretty old. I took the car in to have a coolant flush and they said the radiator cap was not holding pressure so they replaced it and everything was fine according to them. The low coolant light was still on. When I took it home the temp climbed up above 100*C, I was getting nervous because I assumed the temp should stay around 83*C. I took a couple trips ~35kms each way, when I was on the highway the temp stayed around 85*, but if i was idling or stopped in traffic the temp gauge climbs back up to above 100*. If I turn on the A/C the temp guage stays cooler around 85*. I was getting frustrated trying to figure out what was going on so I took it back to the shop explained everything to them and this is what they told me:

They hooked up the car to the computer and confirmed that the radiator fans are coming at 105* and shutting off at 95*, which is what they're supposed to do. They pressure tested the cooling system and no leaks or loss of pressure. They used an infra-red heat gun and confirmed the t-stat is opening and closing at the correct temperatures. They said low coolant light is most likely a bad level sensor, but said it won't interfere with the performance or operation, but could change it if I wanted to. Other than that they said the car appears to be working as it's designed.

My question is this, does this seem like the cooling system is working fine? Does the temp gauge move around (up a bit then down all the time?) I always thought it should pretty much stay consistent at all times. Is there anything else to check? Needless to say I feel like I've exhausted all possibilities that I can think of and took it in and was told it's working ok, but it just seems weird to me. Maybe the car was running too cold the first year so now I think it's running bad but now it's actually working. Thanks for your input.

ok I checked the oil and it's clean, looks good (cap and dipstick). I checked the coolant level at the radiator cap and you can see fluid at the filler neck and I checked the level at the reservoir and there's about an inch or so of fluid sitting at the bottom. The part that's throwing me off is the temp read dead steady at about 83*C for a good year, then I changed the water pump which was leaking causing the low coolant to come on. After I changed it, the light went off and the temp held steady at 83*C again until the leak started. But apparently that temp is too low for this car, I'm starting to think the t-stat was stuck open for so long it seemed the cooler temp was correct and now it's getting stuck between open, closed, working properly....but that seems like a stretch that it would stay open for nearly 2 years.

Originally Posted by squider

ok I checked the oil and it's clean, looks good (cap and dipstick). I checked the coolant level at the radiator cap and you can see fluid at the filler neck and I checked the level at the reservoir and there's about an inch or so of fluid sitting at the bottom. The part that's throwing me off is the temp read dead steady at about 83*C for a good year, then I changed the water pump which was leaking causing the low coolant to come on. After I changed it, the light went off and the temp held steady at 83*C again until the leak started. But apparently that temp is too low for this car, I'm starting to think the t-stat was stuck open for so long it seemed the cooler temp was correct and now it's getting stuck between open, closed, working properly....but that seems like a stretch that it would stay open for nearly 2 years.

Plus I've looked at the location of the t-stat (buried behind the air intake / throttle body) and it looks like a b*#@! to take out and put back. The shop quoted $200 because they said it's not an easy one, but advised against doing it anyway cause everything seems good.

I have a similar problem- 228,000 miles. replaced bad water pump last week and everything was fine untill 2 days ago suddenly started running way hot (in the red) and using coolant. no leaks while idling/sitting made me think headgasket. I got it all torn down in the driveway (about 5 hours) and head gaskets are old but not blown. initial disassembly showed water in the throttlebody/air intake from air filter box. cylinders are clean and dry, coolant (original) is filthy. no water in the oil. engine had seemed to lose compresion because after it overheated and died on the interstate it wouldnt restart, and the engine seemed to turn over way faster than normal from lack of load. could it just be a bad thermostat? why wouldnt it restart once it was cold??

I am having the same problem with my 02 grand prix (191,000). I've replaced the radiator tubes, both fans work when parked, flushed the radiator and put a whole new thing of 50/50 in it. Low coolant light is still on and hits 260*F (parked), 210*F (at red light). When I drive it goes down between 210* and 160*. This is so frustrating.

Originally Posted by dsmuts

Air bubble? Thermostat?

Are you replying to me or 228k?

Originally Posted by Sushamouf

Im thinking you have an air pocket. That will cause temp to fluctuate rapidly. Try bleeding the system.

Sent from my Droid

I have bled the system.

Originally Posted by dsmuts

you

Oh, well I dint quite underhand what you're trying to say/ask.