Help with Temperature issues...

[ToniMJ]

Hi there! I recently purchased a 1997 Chev. Monte Carlo with approx. 100,000 miles. When I test drove the vehicle I noticed that the temperature gauge fluctuates consistantly. I pointed this out to the car lot and they put in a new temperature gauge and thermostat. It seemed fine for about 4 hours worth of interstate driving. When I reached my destination, I parked it, and the next time I drove it for about 35 minutes on the interstate going approx. 55-65 mph's. That first time and everytime I drive it on the interstate it goes all the way up to 3/4 of the way to 260 and sometimes even triggers the 'heat' word to light up. As soon as I go to pull over, just in case it over heats... it's back down to the half way point again. While I'm driving around town it's fine...even sitting in rush hour traffic for 2 hours it's fine...it's just when I'm on the interstate. I just had the radiator, temperature gauge, and thermostat replaced, along with some vaccuum hoses; and have taken it to 3 mechanics all of which tell me they can't find a problem. Is this just a common thing with this car or is there something wrong? I've also had the oil changed to make sure there wasn't any coolant in the oil and there wasn't. HELP ME PLEASE!!! I'd be eternally greatful!

[richtazz]

THere is probably air trapped in the cooling system, and it's only working it's way to the engine at steady highway speed. It's a common issue on your engine, and beeding them can be a nightmare. Take it to a shop that specializes in A/C, cooling system and radiator work if you can't do it yourself.

[96montez34]

Unfortunately, I don't have the solution, but my car is doing the exact same thing as yours.
My 1996 Monte Carlo 3.4L DOHC has been into the shop three times for cooling issues. The last two times were for the exact symptoms you decribed above. The shop replaced the Coolant Temp Sensor, and now they replaced the thermostat. I think that probably just intoduced even more air into the system. Can someone please describe the proper procedure to bleed air from the coolant? Thanks

[richtazz]

Try this link (I hope it works):

http://127.0.0.1:9001/servlets/BlobS...m&cellId=37225

The most important step is opening the bleed valves while filling/draining, and running the engine through 3 heating/cooling cycles to insure the air has purged. Another thing I do, especially on the newer 3100's where the thermostat mounts sideways on the end of the intake, is drill a 1/8" diameter hole in the t-stat flange to help steam escape if air gets trapped behind the t-stat. Make sure you install the t-stat with the 1/8" hole at the top (12-o'clock position) to ensure the air can escape.

[Rally Sport]

I think the answer is in your car's airdam, unless that thing is hanging down and isnt cracked or whatever.

Although itd be more noticeable in rush hour.

[96montez34]

Hi, I looked at the radiator and the fan(s) shroud appears intact, but I did notice a lot of bugs and some of the cooling fins are bent.

I bled the air from the coolant bleed screw with the engine warm and running, but the "hot" light still comes on during freeway driving.
It stays on for a few seconds, and then goes out. The coolant is at the proper level, water pump was replaced, and thermostat was changed twice by repair shop. I am thinking of buying an infrared thermometer (non contact) to see if the engine is really overheating.

Could it be the head gaskets? Is there an easy way to tell if it's a head gasket, or is a compression test necessary? If it's the head gaskets, I'm thinking I may be better off trading her in on a used car. Should I try drilling an 1/8 hole in the thermostat flange that richtazz mentioned to fix it? Thanks

[heather2011]

I have a 96 monte carlo and i am having heating problems. There will be heat for just a little bit but then the gauge will start climbing and at times peg out and kick the hot light on. Then it will come back down and go back up. have changed the thermostat and radiator cap and checked all the hoses. At a loss as to what it could be unless it's the heating core. Any suggestions?

[racerjim0]

You need to open the vents to let air out. There are two brass vents, one on a little tower toward the left of the engine and one on the thermostat housing. Make sure you radiator is full and wait till the temp gets close to opening the thermostat and crack both open until water comes out. Now the bad news!This usually means you have bad intake gaskets which is a common failure on these engines, Buy the gasket set from GM/Chevrolet. Their new kits come with new intake bolts. I think I paid 76 bucks for the set. Stop leak may get you by for a while.

[dorfboy]

It sounds as though you are having issues with coolant flow. If you honestly did need some new intake gaskets then you would be leaking coolant and if that was the case I am sure that you would have noticed. The proper way to bleed the system is to open those bleeder valves and when water starts to flow out with the engine running, close them. If it does not work I will wait until it cools down a bit, open the radiator cap and start the engine. I will watch and see if air bubbles will come out. It may take some time, but just keep topping off the coolant until coolant starts flowing.