OK guys I'm completely lost here.

I've been having cooling troubles for quite some time; went through everything I could think of, thermostats, caps, new head gasket, etc. etc. etc.

Finally put a Fluidyne radiator in. Now it will not overheat, but occasionally as I drive along the temp gauge spikes to 3/4 or full hot, then after 30-60 seconds drops back down.

My first thought is bubbles in the coolant. So I attempt to bleed the coolant (96 GSR, no bleed screw) by running with radiator cap off. Run for at least 20 minutes, no sign of the thermostat opening, but coolant bubbles up out of the radiator neck in occasional bursts. I can hear and feel big bubbles in the upper hose, which explains the bubbling out of the top. But all this time I can't get the thermostat to stay open, so there's no flow through the system as far as I can tell. If I rev up the engine to heat it up, the "spouts" out the top start getting pretty dramatic so I backed off.

I'm wondering what the heck is going on - if I can't get the air out of the system I can't eliminate that as the source of my problems, but I'm wondering if I should pop the top off and try retorqueing my head bolts or something because I can't imagine how this much gas could have entered my system.

 

If you have a continuous flow of bubbles coming out of your radiator fluid, thats usually a sign of a leaking head gasket. did you get the new head gasket before or after you got the fluidyne? If you overheated it before the new radiator?

 

Yeah I'm thinking same thing but there are some big bubbles... seems too much for just a leaking head gasket considering the car runs pretty well.

I think tonight I'll try retorquing the head bolts; do a compression test, and see what I learn from there.