Overheating!!! Please help!

Hey, I got a 91 LS. Shes just been taken out of the garage for the first time since spring. Whens she idling the temp seems fine. Just up about a mm more than usual. But as soon as I start to move her, or rev her the engine temp starts to rise right away! The water pump is new. Could this be a thermsat problem, or a air pocket in the system, The rad is new too, and it was drained twice by me this winter. Any clues guys/ gals? Please help! Shes supposed to get a alinment monday, but I don’t wanna take her out like this! Please let me know! Thanks!


It sounds like the thermostat to me… I would try that first anyway – it’s not like they’re expensive.

Alittle more info.

Went out to have another look, and I held onto the hoses. The tops hose seems hotter then the bottom hose that goes to the thermostat. Could this mean that is the problem?

Also when it was drained I spilled some fluid, so I just replaced it with water. Could it be a problem with the mixture? Could that casue overheating?

Also theres little too no coolent in the coolent res. Could this casue a problem.

Please help!


I ran her with the cap off for alittle while again yesterday, then added some water to the coolent res.

Took her for a spin today, and she overheated alittle bit, but not as much as yesterday. But still whenever I take my foot off the gas she goes right back to normal?

Do I need to let her idle for alittle bit with the bleeder valve open?

Any thoughts? Please let me know! Thanks!


Another update!

Went out today! Took the cap off and opened the bleeder valve. Let her run for awhile.

Then I was moving her to my house from my parents, and I got alittle ways, maybe 5 kms, with no prob, then the temp started to rise again! So I pulled into a parking lot, shut her off for a sec. Started back up again, and the same thing happens. But the strange thing is that as soon as you take your foot off the gas, shes goes back to normal in a matter of seconds.

So I went out again just then, took the rad cap off and let her run for about 20 mins. But sure enough when I put the cap back on, and reved her alittle the temp shot right up again! So I shut her down and came here!

But when I had the cap off I was getting some bubble, some very big, some med, and some small. Could this be just air in the system, or could this be a head gasket?

Someone please let me know!

Could it be the thermostat?
The headgasket?
The gauge?
Air lock?

Any ideas?


Well, you know what’s worth a shot? new rad cap. Cheap and easy. If that doesnt’ work, try replacing the thermostat. It’ll take you probably an hour including flushing the old coolant out and putting new stuff in.