3.1 overheated......now temp gauge reads higher under normal conditions after overhea

[gacowboy30]

Hello everyone, I recently purchased a used 1991 pontiac grand prix se. I found out that the cooling fans were not coming on a few weeks ago unless the a/c was on. I replaced the temp sensor, radiator temp switch and I tried both relays in each fans slot and they both worked if the a/c was on of course. After I did all of this, the fans still did not work and the car got up to 250 degrees and began bubbling and as soon as I noticed it I turned on the a/c and drove about 1/4 mile and it cooled farely quick. Since it ran that hot, my temp gauge is reading higher than it used to before that and I also noticed that when I drive at normal speeds and let off the gas, the temp gauge reading goes up several degrees immediately and stops just under 220, if I get back on the gas it drops back almost as fast. Just as a side note, the old temp gauge reading was just barely above the dark line halfway to 220 which should be about 192-195 or so. I'm at wits end and looking for any direction to head into now to figure out what is going on with this thing. If youd like to help and need more info, please email me at [email protected] Thanks in advance!


Robert

[richtazz]

you have air in your cooling system. You need to bleed off the air usung the bleed valves at the t-stat housing and transfer tube by the water pump. A little secret to help bleed the air, drill a small 1/8" hole the t-stat flange, it will help the air escape past the t-stat when the engine is cold, reducing the risk of a steam pocket forming that could cause a blown head gasket.

[gacowboy30]

Thanks richtazz, I have one more question now that I have located these bleed valves, what should the procedure be? Engine cold not running, engine cold running, engine warm not running.......etc? I just want to be sure to do it properly. BTW, I have never seen a cooling system on a car have these bleeder valves on it. Why not on all cars or is air pockets just a problem with this particular engine?

[richtazz]

just the GM 60 degree v-6's (2.8,3.1,3.4) What you want to do is start the car and let it warm up until the t-stat opens, then open the bleed valve on the t-stat housing. coolant and air should bubble out, when air stops coming out, shut that bleed valve and open the other one, letting the air bubbles escape until just coolant comes out. Shut the engine off, and then start it right back up. and repeat the above process. Also, jack the front of the car up so the radiator is above the engine, it helps purge the air faster. Keep an eye on the temp guage and don't let the temp get too high when you initially start it. A good repair manual should have instructions on how to bleed the air, I believe the owners manual says also.