Okay, sorry to add another overheating threat to the pile, and I think I've got most of the info I need from searching this forum, but I wanted to share my problems and see if they matched up with anyone else's.

Okay, last week I was driving my car home from work, the weather was roughly 98-104 outside. I had the a/c on and the temperature was doing fine the whole time. A little on the warm side, but nothing to write home about. Then I parked the car, ran into the store to pick something up and came back outside and fired the car up with the a/c running. After getting about half a block away from where I just was, I smelled coolant and looked down at the gauge and noticed the temp gauge was pegged in the red.

I was at a red light, so I kinda panicked and shut it down for a minute, when the light turned green, I started it again, jumped over 2 lanes and pulled into a parking lot. I opened the hood and noticed the overflow tank lid had blown off and coolant was boiling over. I had the car towed to my place (Friday evening, didn't wanna try and get it fixed or gimp it 12 miles to my place) and then on Tuesday my dad came over and checked it out while I was at work. He noticed that the temp sensor on the water pump wasn't working thus not triggering my fans, so he replaced it and the car had been running GREAT since.

Now today, I was driving the car around up here in the desert (visiting my folks) and it's about 112 out and I noticed the car running warm (just over 1/2 way on the temp gauge, which is what, like 190ish?) I went and picked up some water wetter and on my way home I noticed the temp gauge spiking a bit, most noticeably when my foot was off the gas pedal. I added the water wetter and went for a drive with my dad. Again, ran on the warm side, but nothing too bad. We drove around a bit with the a/c on to test it (again, no issues) and went and got some ice cream for my mom. As we pulled out of the parking lot, sure enough, the car was overheated within about 20 seconds. Just shot straight up.

So here's my plan right now: replace radiator cap, bleed the system, and if need be, replace the temp sensor on the water pump. Hopefully that will do it, but if anyone sees these symptoms as signs of a different problem, please let me know, I really want to get this sorted out!

Thanks a million,

Kris Horton

 

Do you have a stock GM radiator cap or a cheap parts store cap.

 

Stock.

 

Anyone?

 

When it overheats are the fans running? If you are running your AC the fans should be running anyway, and that temp sensor shouldnt matter. Sounds like a thermostat acting up to me. If it only happens when it was hot, then parked, then drivin again, the thermostat may be sticking.

 

Over heating contributors:

• air in the system (did you bleed it?)
• improper coolant mixture
• radiator cap not holding pressure
• external leak
• fans not operating properly (fuse, waterpump sensor, bad fan(s), bad connection in the harness)
• something blocking the radiator (sucked up a bag)
• clogged radiator (internally)

 

Looks like I may have solved it. I opened the bleeder valves after driving for a bit and seeing the temp go up. It bled air out for about 3-5 minutes. I have yet to test it again with the A/C on, but I will do that next. I'm thinking about getting the radiator flushed anyway.

Kris

 

Air in the system would explain the second time it overheated, but not the first. If it had been like that and not overheating before, it didnt have air in it then. When it overheated the first time, and pushed coolant out, it pulled air back in to replace the coolant.

 

The first time it overheated, it was the sensor in the waterpump not telling the fans to come on I believe.

 

where is the bleeder valve your talking about? that the drain plug on the radiator?

 

Photo from Shoebox's site show bleeders on radiator hoses:

http://shbox.com/1/bleeders.jpg