OT-'95 olds acheiva heat isues

I've been having a kinda odd problem with my car lately (95 acheiva, 3.1 V-6). The thermostat was sticking, the engine got hot then the temp guage dropped and warning light went away- coolant came out of the overflow tank which has the radiator cap on it.

I had the thermostat replaced by the local mechanic, and it was fine the next morning on my way to work. That night on my way home the heat worked at first, then after a little while it was blowing cold. It was hot & cold the rest of the way, as I stopped at the farm, the grocery store, etc and went through town.

On the highway I don't notice any problems, other than warming up then going cold for a little bit. The temp guage goes borderline red before the heat comes back and then it drops off below 140 and comes back up.

Going through town it kinda gets warm, then cold, then warm, and it fluctuates a little bit.

Is it a bad thermostat outta the box?? I stopped back by the mechanic the first day and he said he was having troubles with another car with the same engine- put 2 thermostas in it and it was still acting up. He said mine could be that the radiator fan isn't coming on, but the temp does go down in town. Haven't gotten out yet while it was warm to see if the fan was running or not though.

Any ideas???

Donovan from Wisconsin

look around on the top of the engine, maybe on the thermostat housing area for a square head plug, or a bolt going in to the coolant. many cars have a bleeder to bleed air out of the cooling system. usually if the radiator is lower han the top of the motor, there will be a bleeder.

Head gaskets, common on 3.1.

Get a bottle of Bars stop leak and pour just the liquid in the radiator. Shouldn't take long before it's smoking out the exhaust.

I have an '95 Olds Cutlass Supreme that the guage is showing 235-250 degrees once it warms up and stays there. Hooked a diagnostic tool to it and that only reads 212 degrees. The car has always ran little over 200 on the guage since new, but this last fall has been running warmer then ever before. Have an electric guage in it now because I tried a different sender for the factory guage already. Then tried a GM thermostat since I throught that could be it and was told not to put in an aftermarket thermostat. Then also tried a new temp sender for the computer that would control the fan and still no luck. It was warm enough the other day to try out the air conditioning and the fan did come on at times, was in the 50's. Hopefully Allen chimes in here. chris

Forgot to mention I'm not boiling over or loosing any coolant.

Those are bad for getting air pockets. I agree with Glennster it should have maybe 2 bleeder screws on it try to bleed the air out and see if it helps.

I've been having a kinda odd problem with my car lately (95 acheiva, 3.1 V-6). The thermostat was sticking, the engine got hot then the temp guage dropped and warning light went away- coolant came out of the overflow tank which has the radiator cap on it.

1) sounds like a bad stat,,, I know around 2000 GM has only one temp sender/sensor,,, the ECT sensor for the electronic engine controls also works the temp gauge,,, when a Gm flys off hot it will turn the temp gauge off and the cooling fans on,,, nice engineering eh! BTW I use OEM stats when possible

I had the thermostat replaced by the local mechanic, and it was fine the next morning on my way to work. That night on my way home the heat worked at first, then after a little while it was blowing cold. It was hot & cold the rest of the way, as I stopped at the farm, the grocery store, etc and went through town.

On the highway I don't notice any problems, other than warming up then going cold for a little bit. The temp guage goes borderline red before the heat comes back and then it drops off below 140 and comes back up.

2) Best i can tell the temp gauge is not lie'n,,, you can tell by heat and no heat,,,, could B a few things,,,, could b air bound,,, they are tuff to git all the air out,,, you would figger that by all the cool down and hot cycles the over flow system would take care of that and it does most of the time,,, check that the tube from the rad to the over flow bottle is not restricted are stopped up,,, replace the rad cap,,, I have seen the nipple were one of the heater hoses connected to the engine rite near the thermostate git stopped up are restricted and also a plugged heater core,,, Gm FWD's will heat if the flow thru the hearer core is restricted,,, Really tho it sounds like its low in coolant,,, low coolant will act zacly as what you have,,, gonna rule out the rad less its leak'n,,, a plugged rad would not recover once it ran hot,,, its possible the water pump impeller has worn/rusted off tho I have never seen this on a 3.1,,, water flow needs to b checked thru the heat core it will explain alot of things,,, intake gaskets are a problem on 3.1 and 3.4's (same engine) ,,, water in oil or oil in water,,, no pattern to'em,,, the fun part of B'n a mechanic izzzzz you marry alot of problems,,, its his problem to verify the correct function of his replacement part or what issue is causing the problem,,,wham bam thank you mamms make ya alot of money,,, good mechanics verify that the customer leaves with a fix the best he can do is use a OEM stat if it fails no harm no foul,,, sounds like a do over if he does not pocess the skills needed to diagnose the problem BTW I don't think its a cool'n fan issue,,, at highway speeds its not needed

Don,I think Mike is correct.Those closed systems on the GM won't tolerate low coolant.If they get just a little low on coolant the heater won't work.There should be a bleed screw "PROBABLY On TOP OF THE THERMOSTAT HOUSING" to bleed that air out so you can get max amount of coolant in there.That air is displaceing coolant right now.Just open the bleed screw and let the air out.You may have to do it 2 or 3 times to all the air out and all the coolant in.

matthies,take that radiator cap off with the engine not running.Look down through the top of tank at the core tubes.If they look corroded or clogged you need to remove the radiator,take it to a shop and have it rodded out.That coolant has to circulate properly or it will run warm.Running the Ac will make it run warmer with a clogged radiator.And both fans also need to work right on these cars also.Check the fan motors and the sensors.

Don,That bleed valve will look like a brake bleeder or grease fitting.

It may be worth the trouble to back-flush the heater core with clean water too. I posted something on that a day or so back. Improved heater performance 100%.

Feel the upper rad hose when no heat comes out.If real hard due to excessive pressure,my vote goes for head gasket.Too much pressure will not allow coolant flow through core.

On these engines, you should always assume the head gasket is blown until it's been proven otherwise.

Put a cooling system pressure tester on the radiator and start up the engine. If the pressure heads through the roof you have a blown head gasket.

I agree with the coolant level. Sure sounds low to me. When the PCM took over control of providing serial data to the instrument cluster, the gage does not "Turn OFF" when the engine gets hot.

The best way to refill any cooling system is with an "air lift". It pulls a vacuum on the cooling system then the vacuum draws the coolant in. No air pockets. The 60 degree V6's are not known for head gasket problems, that is reserved for the early Quad Four engines.

Both my 94 & 96 Olds Cira with the 3100 engine I had to replace the head gaskets on, both putting exaust gas into the radiator.