Temperature fluctuations

[EddieHaskell]

Good evening, folks...

Well, driving back from downtown, I noticed my coolant temp climbing well beyond the usual 185, up to about 220. I turned on the heat full blast, which got it cooled but alternating between 170 and 210 the whole freeway ride. Once I got off the freeway, it climbed back up to 220 and held there.

Back in January, I had a hole in my waterpump and air had gotten into the system, but with that one I noticed that during the "hot" phase, the vent would blow cool (little to no coolant in the shroud, which makes sense) but this time the heat was consistent and constant... I don't know what this could be, and I'm doubting it's the thermostat, as I changed that not even six months ago, and Pontiac replaced the water pump three days later... I dunno', and suggestions would be greatly appreciated. Thanks.

[hockeyman]

Re: Temperature fluctuations

Check the radiator fan motors. At speeds above 30mph, air gets forced through the radiator and cools the coolant. At lower speeds, the air doesn't pass through the radiator as well, and the engine's temp begins to rise. If the fans don't kick on, the temp will keep going up into the danger zone.

Just as a precaution though, I'd recommend re-replacing the thermo and bleed the coolant afterwards. Air pockets can get into your coolant lines and cause havoc. If and when I replace my thermo, I get the engine up to operating temp (in park) and slowly loosen the bleeder screw on the thermostat's housing.

Bleeding the coolant 1
Bleeding the coolant 2

[Joey41]

Re: Temperature fluctuations

Definitly bleed the system as stated above my post. From what I have heard is that your coolant system can get corroded and clogged from air being in the system for longperiods of time. I have a 97 camaro, mine was bad-had to get a new radiator. You may look at getting the radiator checked/tested by a professional radiator shop. Of course be sure there is no blockage in front of the radiator as well.

[shenanigans]

Re: Temperature fluctuations

just an fyi, our temp guages are insanely inaccurate as well.

[BLLDOGG]

Re: Temperature fluctuations

check your radiator to see if something is blocking it or if its just dirty.

[EddieHaskell]

Re: Temperature fluctuations -- Fixed

I decided to stop being a stubborn jackass and redo the little stuff that I did in January. I replaced the thermostat again, and had a friend at a local shop completely flush the system (my coolant was in a bad way. God, do I hate DexCool) and then I took it for an hour drive where it never got above the 185 hash mark. It seems to be okay now. I don't know if I really needed to replace my t-stat as it was only six months old, but all in all, it was a quick and cheap fix.

My sincere thanks to all for the support and ideas, they were really useful, heck, they were the fix! Thanks again.