I have a 95 3.4 5 speed 120k miles
I just changed the water pump 6 months ago
the freeze plugs were replaced a year ago
I just replaced the thermostat yesterday

So my car sometimes overheats. Some starts I start my car it will get really hot like 250ish and after a min of sitting there or sometimes I restart the motor and wait a min it will cool off and warm air will come out of the vents. Where before it was cold. (I had the heater on). This morning it overheated. So I went to work and when I turned it on in the afternoon it was fine running with no problems.
It was bubbling out of the overflow for awhile until I turned the cap on there better.

Someone told me I might have an air pocket. Someone else told me my radiator cap might not be holding to the proper pressure. And someone else told me it might be a blown head gasket.

I am not sure if this is related but when I was driving it yesterday after I changed the thermostat and today when I was accelerating I herd a sort of thunk under the hood.

Other than the overheating it seems to be running like normal

I need some help. Thanks

 

did u bleed the air out. theres little bleeder valves that u unscrew a little to let the air out. very well could be head gasket. do a compression check on it.

 

Bleed the air out =P That's the problem. Your system is air locked.

 

Borrow a pressure test from autozone and pressure test the coolant. See if it will hold pressure. All three of the above statement are true. Air pocket, bad cap, head gasket. The bad part is the air pocket and the bad cap can cause the head gasket to fail.

I will add a couple more, Fans not turning on/working. The radiator is sludged up and you can not get enough coolant thru the radiator.

 

I had the same issue on my 2000 v6... one thing I noticed is use antifreeze and not water. but what I did was change the cap, make sure the resevoir hose is not pinched under the battery. I changed out the fusible links (I think thats what the are) in that box on the drivers side and made sure the fans all work. and make sure to bleed it... I did all this at once but I think the cap and bleeding it was what fixed it.

 

where is the air socket located

 

there little screw valves. should be at the front of the motor in the colant lines. on my lt1 theres one at the bottom of the tb and another in the heater hose rout. they arent very big and have a regular screwdriver head on the screw that u losen to let the air out.

 

where is it at on the picture

http://www.zorly.com/images_camaro/0...oski%20Jr..jpg

 

You realize this is the V6 section? I saw two bleeders. My edit did not work real well. If you zoom in just below the throttle body you can see yellow circles.

 

i do have a v6 thats not my engine ive tried to look for a v6 engine to get better refference