Temperature Issues

Ok, for a while now me and my coolant system have been in a epic battle. I had a leak, fixed it. Recently, it was running hot and dropping to normal. Well i blew the pinion seal on my differential so while in the shop i got the thermostat replaced and last week i replaced the raidiator cap as a precaution. Now its like round 3. i got my car tuesday. it lasted to this afternoon without problems. On my way home from school it was fluxuating everywhere. It would get hot, then drop to normal then back up and back down. When I was at lights it did it too as well as moving. I am befuddled.

have you checked to see if the coolin fan is working?

coolant temp sender?

Look at the thread Stupid Question About Coolant!
I was having some of these same issues and it turned out that the Coolant temp sensor was the culprit.
It is on the second page.

my fan is working, it actually turned on before the car was at normal temperature

my fan is working, it actually turned on before the car was at normal temperature

Funky CTS will do that.......

I taking your advice on this, but i get the feeling this is gonna be a pain in my ass to replace.

Actually its much much easier then it sounds. It is attached to the bottom of your waterpump. Just make sure you buy the AC Delco one from your local dealership instead of the $10 one from the auto store. You will pay about $25 at the dealer but it is well worth it. It comes with a type of sealing compound already on the threads so you won't need any teflon tape. Just get the other one loose and be ready to put the new one in immediately to avoid spilling anymore coolant then neccessary. Tighten er up, and your good to go. Just make sure you also disconnect your battery to reset your computer before you start it up too. The whole thing will take you less then 10 minutes and it is a cheap and easy fix. If it turns up to not be the sensor then you atleast have taken that out of the equation. Good Luck!

If it matters, i have a v6...

anyway,last night I went to my friends house and we tried to diagnose the problem. Well of course my car decided to be fine. I drove to his house no problem, it just got about to normal temp. So we had it idling in the garage to see what it would do, well the fan kicked on around 185ish which we thought was weird, it kicked off and it never got overly hot. It didnt move for like 10 min. So we took it for a drive, it was fine. We sat on the side of the road and then it was normal, it heated up to about half way on the temp gauge and the fan kicked on and went back down. It makes no sense.

I really am confused. I am low on funds so im not trying to go out and buy everything without really knowing whats up.

Today, in the morning, i warmed my car up for like 5 min or so before school. It was fine all the way there. After school, i let it warm for like a min or two and it was overheating but not reaching the red. the fan would kick on. My friend drove it, it was hot for like a min and went regular after turning the heat up, turnedit down and it was fine. Another thing this morning i noticed was the fan kicked on abut 180, which i think is weird. Also, when the car was running hot, it was blowing cold air into the car, with the heat on.

My friend and I have NO CLUE whats going on and I cant stand it.

"Hello, McFly, are ya in there?" :wave:

Something is wrong with your coolant temp sensor circuit!!!

Don't want to spend moeny whatever, check the wiring out and get some specs on the sensor, most s/b around 400 ohms cold.

Your water pump could be bad and intermit. After all there is a winding noise coming from your belt that isn't the belt istelf because it's fine. (i'm the friend he speaks of that has worked on it with him)...today we flushed the block, radiator, and heater core. i drove it and it was fine. we let it idle for a while and it didn't even get hot enough for the fan to kick on. later he drove it around and says the temperature would flutcuate rom 240 to 160. I can only think of three things...a)his water pump has problems, or B) when he fixed his "coolent leak" we just put some stop leak in it because the leak was in the resivoir/over-flow tank, it was just cracked. the stop leak didn't work so with his dad he put more in. i think it could be claugging up the heater core, because when the car over-heats the heat blows cold air. or c), it's cavitating, where the coolent is boiling in the block and creating air pockets and the water pump cant pump it. this is possible but illogical, cause if it cavitates and it's boiling it's overheating real bad, and well he would have toasted his motor by now. any of this sound reasonable to anyone? i have a 90 trans am and i know my motor pretty well, but i'm doing the best i can with his. thanks for the help

Your water pump could be bad and intermit. After all there is a winding noise coming from your belt that isn't the belt istelf because it's fine.

Take the belt(s) off and turn the pump pulley by hand, shouldn't be any drag on it. A pump failure tho, can not be intermittent, BUT, given the amount of engine death dumped in it (stop leak) there could be a ball of it blocking a passage right there?

If the pump checks ok, then lets go back to the blasted CTS. IF, the wiring and sensor check out, then it is sending the correct information to the PCM based on the situation as it is occuring, air pockets, maybe, hows about a glob of stop leak interfering with the sensor..

But I don't know about that, I believe strongly that the the CTS is the culpret. The no heat issue, there's no heat period at any time? If possible, I know we're dealing with a 4th gen here and half the enigine bay is under the windshield, check the inlet and outlet hoses for the core. I'd love to say the inlet is hot and the outlet isn't and agree with you fully the "stop leak" became "stop heat".

Anybody check the rest of the hoses out to make sure none are collapsing and the stat is functioning correctly (those fail intermittently)

Well it wasnt the CTS. It was the heater core. It was/may still be collaged a little and maybe developing air bubbles. We have flushed it well and it seems to be fixed...but lets not jump to conclusions.

where there's stop leak, there's problems. once you've cracked a motor open and see what that stuff does, you'll know, for now, trust me, stop using it, it's not worht it!

I hate to bump and old thread of mine, but I had spoke to soon in my last post. About a month ago I took it to my mechanic to see what was wrong. We figured out before hand air was getting into the system, we just don't know where. So I took it too him and he said it was a tiny hole in the head gasket. being that, my dad didnt want to fix it. So the car has been sitting at my house. I have driven it around town a few times. It will take like 10 min to heat up then the temperature will rise, but never over heat just run really hot. It has never over heated. It is also not mixing with the oil or blowing smoke out my exhaust. I dont think it is the head gasket but I cant afford to get it looked at.