So, ladies and gentleman, I have the world famous 2.2 5speed, and its overheating non-stop
it stops with the heat cranked, which tells me the heater core is not blocked or plugged.
Brand new waterpump, and brand new thermostat still has yet to resolve my issue, 4th cylinder is also running 50 degrees cooler than all the rest of my cylinder's
What do you guys think?
Im leaning towards 1 of 2 things, head gasket, even tho there is no white smoke, and oil is clean as could be, or perhaps bent valve, is has a slight knock on start-up but this is a known issue so I ignore it. It goes away after it warms up.

I have a spare 2.2 that I can drop in, but there was a few things I wanted to do to it before I did that.
So my next question is, are there performance cams or any other internals I can upgrade before I drop the new engine in?

You bled the system if possible?

How I bleed it is, take off the radiator cap, let it run. The level will drop slighty, but when the t-stat opens up, it will drop quite a bit.

When air bubbles stop coming to the top, you have bled the system of air.

Fill up the overflow tank, and put the radiator cap back on.




- 2004 Cavalier - 124k, owned since new

call me crazy, but there is no rad cap on my radiator. Maybe I have just failed to pay close attention to it tho, which is more than possible

Did you install the thermostad correctly, make sure the copper piece of the thermostat is facing toward the water pump.

thermostat is in correctly, with these engines, it's kinda hard to install them backwards

Try this!!! I have a 2001 2.2ohv and i had the exact same problem! I replaced the thermostat, and the water pump and it was still overheating. Then one of my buddies told me that they are a very sensitive pressure system. I changed the cap on the overflow tank and it stopped overheating! After the money and time i spent replacing those parts it was really a kick in the but to spend $4 and fix the problem!

Do the heater hoses feel warm going to the rad? Does it overheat sitting at idle with the heater blasting? If you let it get warm while sitting at idle, does the radiator get warm or does it stay cold?

I had a similar problem on a different vehicle. I tried bleeding the system 3 different times and it still would overheat randomly. I let it idle till it was starting to over heat, then felt the rad and found it and the hoses were cool. That means the thermostat isn't opening up due to air or a faulty thermostat. I found that if i drilled a 1/16 in or smaller hole in the thermostat and then bled the system, it eliminated the problem. Don't go crazy on the hole size though, you want the smallest hole possible that will let air out, but not bypass the thermostat much and still let your car get warm.

If all else fails... the headgasket is the place to look. My LN2 has had a headgasket go on it and it kept overheating as well. Replaced the water pump and thermostat. No sign of oil loss, just coolant. Replaced the headgasket and it ran beautifully.

Just a quick little note, but did you check the condition of your radiator? I had a overheating issue a few years ago and it turned out that a large majority of the fins on the radiator were missing. Replacing the radiator fixed the problem.

The large temp difference of cylinder 4 would concern me. Have you done a compression test on it yet? If so, how does it compare to the rest?

i didnt read most of the post so sorry if i ask a repeat question. is your fan turning on?

well i also have an over heating issue i have a 1996 2.2L my cars only over heats while driving, i have had a head gasket replaced so i know its not that i have bled the system and the bubbles came out. After turning off the car a loud clunking noise from the hose thats comes off the engine and goes into the rad any ideas?????

just to let you guys know, I had the exact same issue, switched out rad, water pump, thermostat with no luck, so what did I assume? cracked or warped head, so I swapped the whole engine. Same issue. What was it?
The gauge........
Do yourself a favour and go to wally world and buy a cheap aftermarket temp gauge, hook it up and drive around for a day checking it out