i have a 96 ciera 3.1 and i just changed the anti freeze prestone green but now i have no heat and the temp gauge goes to hot then cold and back and forth so im sure its air in the system . there are two bleed valves one on the thermostat housing and one on the engine going to the heater core what is the proper procedure?
ok easy peasy,
When filling the system you need to have BOTH bleed valves open, until coolant starts flowing out of them. (car turned off) When coolant starts to flow out close the one it flows out of, then continue to fill until you cannot fill anymore coolant AND or both bleeder valves have had coolant drip and have been closed.
After filling the radiator as much as possible, top the expansion tank up to the cold line, now turn the the car on.
The manual states to run the car and keep an eye on the antifreeze level. Once you can feel the upper radiator hose getting hot(coming from the thermostat to the radiator) you should technically be bled as far as the manual is concerned.(make sure the expansion tank and radiator are at the proper levels this goes without saying)
I had a 2003 Buick and I for one know these are pains. IF you have trouble bleeding it like this, you may need to purchase a special funnel, one of those spill free funnels that hook up to the radiator cap, and run the engine until the fan kicks on then back off. But I would try the version in the manual before making in big moves.
2 things concern me here.. this is the 3.1 notorious for intake gasket leaks.. my Buick had this.. if you had this you will likely never get it bled properly.. at least was the case with my Buick.
The second thing.. you stated you filled with prestone green is this a universal type? If not does the 1996 have Dexcool as the OEM fill? If it had dexcool, and you didnt get a good flush before adding the green(I am assuming green is not universal?) your in for problems..
EDIT: One thing i should mention, make sure the heater core is all the way open, (temperature dial inside all the way in the red) with the blower off.