99 overheating...still!

[tg1hq]

Has anyone else had this problem?
I've replaced the thermostat, had the cooling system flushed and filled with DexCool, and the car still gets hot! What could it be? I thought the flush would clear any gunk in the system. Why would I still be having troule? I don't see any leaks!

[steve_o]

Did you bleed the system of any air?

[tg1hq]

I don't know, I had a shop flush and fill it. BUT! I did find that they left the reservoir cap off, and I lost a lot of fluid that next day. Even if I topped it off, could there be air in the system now? And how would I bleed it? Is there just a bleeder screw/valve somewhere?

[RahX]

those 3.1s can trap air like you wouldnt believe. what i usually do is this. warm the car up at an idle until it reaches operating temp then hold the throtttle at about 1200-1300 rpm. when it starts to get hot rev it up to about 2200-2400 and let off till it comes back down to 1500ish and rev it back up to 2200-2400 and repeat several times. you should be surging the engine like youre getting ready for a badass takeoff, in park . thats how it should sound anyway. what youre doing is working the cooling system to try and purge the air since the high spots are hard to work the air out of. after you do this warm it up as high as it will go without overheating and shut it down and walk away. let it cool down for 30-45 mins and check the overflow. fill it back up tot he hot line and do it again. hope this helps. i know when i do anythign to the cooling system on those bastids 9/10 i have to do this to get the air out even after i opened the bleeders and whatnot.

[tg1hq]

Awesome tip. Looks I have something to do this Sunday.

[GeoStormRS]

Originally Posted by tg1hq

Awesome tip. Looks I have something to do this Sunday.

There is a bleeder valve on your coolant pipe right infront of your intake manifold that makes this SO much easier.

[wymi]

Originally Posted by RahX

those 3.1s can trap air like you wouldnt believe. what i usually do is this. warm the car up at an idle until it reaches operating temp then hold the throtttle at about 1200-1300 rpm. when it starts to get hot rev it up to about 2200-2400 and let off till it comes back down to 1500ish and rev it back up to 2200-2400 and repeat several times. you should be surging the engine like youre getting ready for a badass takeoff, in park . thats how it should sound anyway. what youre doing is working the cooling system to try and purge the air since the high spots are hard to work the air out of. after you do this warm it up as high as it will go without overheating and shut it down and walk away. let it cool down for 30-45 mins and check the overflow. fill it back up tot he hot line and do it again. hope this helps. i know when i do anythign to the cooling system on those bastids 9/10 i have to do this to get the air out even after i opened the bleeders and whatnot.

Good info, but how can you tell if there is still air trapped after you open the bleeders? After the I changed lower intake gaskets it seems my 3.1 runs hotter. I'm wondering if there might be some trapped air in the system?

[GeoStormRS]

Originally Posted by wymi

Good info, but how can you tell if there is still air trapped after you open the bleeders? After the I changed lower intake gaskets it seems my 3.1 runs hotter. I'm wondering if there might be some trapped air in the system?

Let the engine warm up, open the bleeder while the engine is running. When you have a steady stream shooting out, the air is out. Add more coolant to the surge tank, take it for a spin and repeat process 2 or 3 times until no more air comes out.