1990 Cooling problem, Purge air??

Hi there, :screwy: I'll be as specific as I can here, Had some problems with my 90 Gp. 3.1L
Was comming home on the hiway when it overheated, I had to cut the cooling fans and run them directly off the battery, I have replaced teh thermostat, and cap, I have noticed that the drivers fan doesnt move very fast and has to be spun manually to start, so I know that has to be replaced, but even with the fans running, I drive about 20 min and the car overheats, it will boil over, then when it cols it does draw the coolant back from the resivor. I have tried to remove the vapor lock, but I cant seem to get all the air out. I have noticed that the envirmental controlls dont work very well, and when I bought the car, I switched it to a/c and it overheated. i have it set on bi level and it seems to stay there, once in a while if I changed it to vent, it will take forever to switch, the hot/cold works without problem, but I am thinking that maybe it might be something from the a/c causing it to overheat?? or is it just a vapor lock that I have to purge. I see there is a screw on the thermostat housing and another screw by the cap that if turned open Does allow coolant to bleed through.
Someone told me somethign about Purging the system byy removing the screw on the housing and waiting till all air comes out and I get just fluid. I tried this but all I got was alot of air and water, it seemed just to build up and wanted to blow everything out once it got hot. I used to work at a place doing cooling transfers and never ran across this problem. Is this a sign my water pump is going? the fluid does seem to be flowing through the system, but once it gets hot it just wants to push everything out the recovery tank. If someoen knows something that I can do to fix this please let me know. Thanks. :banghead:

If you keep getting alot of air in your system I'm wondering if you don't have a head gasket leaking? that will push air from one of the cylinders in the the water jacket and then over pressurize the system, force the coolant out and make things over heat in a hurry. If you start the engine cold and have the radiator cap off and you get lots of air bubbles that is a good sign you got a bad gasket. If you can borrow a radiator pressure tester that would help you to be pretty sure too. Compression testing the cylinders is also an way to check too. good luck!

Thanks,
I just tried to purge the system, and I was getting alot of fluid/air right from the start, and the engine had been siting over night. The other thing that I noticed, was every once in a while the engine would bog down, kinda like a jake brake, but it would do this intermitendly, After I seemd to get all the air out, I was able to drive downtown with the fans running, and the temp didnt get too hot. But when I opened the hood the fluid was bubbling into the reaivor tank. Drovew it home and still no heat problems and this time it wasnt bubbling. I'll look after the car has cooled to see if it is usinmg any fluid.
If the head gasket is blown, wouldnt there be a sign of oil contamination, Either on the dipstickl or cap??

sometimes but not always

I just did the head Gaskets on my 94 GP 3.1 and it was over heating still, so I changed the Water pump, Rad cap, and T-Stat. And after all that was changed it started to due what your cars doing. I beleive that it is vaporlocked, I imagen if your get the air out it will be fine.
At least that is what Im Hoping...