95 Oldsmobile Cutlass Supreme SL Overheating Problems

[Cutty_Sark]

Hey guys, I'm new to the site and had some questions about the Olds. About a couple of months ago or so, I noticed the car starting to overheat often, so slowly, me and the mechanic replaced the entire cooling system, starting with the radiator cap, the radiator, upper and lower hoses, thermostat, and, most recently,the water pump, and the car will still overheat. But the temperature gauge doesn't just go up and stay up all the time; it will go up about 3/4's to Hot then go down to a little below halfway and keep on doing this until eventually it is just hot. My mechanic says it could be a blown head gasket, but the oil isn't milky or thick, and when I check the radiator neck after running it for about 15 minutes, there is water in it, but the hoses are hard as a rock and hot as hell, so I don't know what it could be. Any suggestions or advice would be greatly appreciated, thanks

[rich_e777]

Do you have to put coolant in it often? Anything floating in the reservior.

 

If not it sounds like you got something blocking the way inside the engine.

 

Did you replace the sensor in front of the thermo housing?

[nelson480]

The air was bled properly from the system?

Have a block test performed for head gasket problems

[Cutty_Sark]

Well every time before I start my car I check if there's water in it and there is. Is that the whole part with the little screw on it to bleed the air out? If so, no, it was the thermostat itself; at any rate, I'm gonna try and get a cylinder compression test to see if it is a blown gasket too

[jman093]

Is that the whole part with the little screw on it to bleed the air out?

 

Probably, there's also a 2nd one one on the heater pipe on the firewall.

[Galaxie500XL]

Is the cooling fan running, and is it running at normal speed? I've often seen cars that had a (barely) running fan, which can definitely cause overheating issues. If you can't feel moving air from the fan a good ways back toward the firewall, it's probably time for a new fan motor.

[Crazy K]

On my 95, the same thing happened, but I determined it was not truely overheating. It was due to the studs holding the rear maniofld having broken off. the exhaust was blasting the sensor directly. You need to verify what the ECM thinks the car temperature is.

 

On that car I tried a trick: I got a 1996+ 3100 temperature sensor, which has three wires and not two. I also got the harness pigtail that goes to it, and a piece of wire from a defunct 95 sensor (all j/y parts). I went to my car and removed the stock two wire connector and installed the three wire (you can do this yourself, 19mm deepwell, universal joint, extension, and teflon to coat the threads). I then cut off and replaced the two wire sensor with the three wire sensor, the two identical wires are color matched and I soldered them together and heat shrink wrapped them. The third wire, (green) I soldered the pigtail I cut from a junkyard sensor, such that I could plug it into the stock sensor's connector. I did not cut the head mounted sensor's pigtail. I could for the remaining life of that engine select one or the other sensor to use for the gauge and allow myself the ability to see what the car was doing.

 

more info:

1995 uses two sensors:

one wire sensor on the rear head on the corner for guage

two wire sensor near the thermostat for the computer.

 

1996 uses one sensor:

three wire sensor near the thermostat for gauge and computer

[Priscilla]

I grew up listening and watching my dad growing up because dad said all girls should have basic knowledge of cars and a little more because it doesn't hurt.

But anyways,  my intuition and my dad's voice would immediately turn me to checking out the coolant fan and the fuse.

Have you checked the coolant fan as well as the fuse?

Maybe the heater core is plugged thats another thing that just popped into my head. 

Let me know if I was able to help 

[Schurkey]

Kinda guessing they figured it out eleven years ago.