[steve]

i was thinking i had a little air in my cooling system until today. now i dont know what to think. i started the car today just to make sure i was going to be able to move it tomorrow and it only ran for 30-60 sec......after i shut i down i heard what sounded like boiling water from the motor for almost another 30 sec !!!! i thought if i had air in the system i would not hear that noise until the thermostat opens ???

[chiphead]

If it's low on water, it can make gurgling noises even if thermostat is closed. I've seen engines with stuck thermostats boil the water in the water jackets, and blow the lower hose off the radiator.

In a similar way, if the engine is warm but the thermostat is closed, the hot water in the jackets will backflow through the lower hose or heater hoses and cause gurgling when the water pump stops turning. Perfectly normal unless engine is dangerously low on water or the thermostat sticks shut.

I think it's normal.

[steve]

i guess i wiil double check the thermostat but it is new and opens when my guage reads 190 on the dash ! the motor was stone cold and only ran for 30 -60 sec. i could not believe the amount of noise !!!i have never had trouble purging air by simply running the car till hot with no rad cap on...somehow i have a LOT of air trapped (does not overheat but it is cold out) OR something else crazy is going on. its definately not low on coolant either. has a new waterpump too....

["QUICK-SILVER"]

If coolant recovery system isn't 100% up to par, it's easy to get air in the system. Normally finds its way back out once the thermostat opens.

My 77 chevy van's heater core, gurgles like crazy, if you kill the engine before it gets hot. Never loses any coolant in the jug, and radiators always full when hot. Coolant level in radiator is down a little when cold. New cap or hose to jug would probably fix it.

FWIW Water pumps are stronger than you'ld think, any air gets shoved all through the engine on fire up. Cut it off and all bubbles have to gurgle back to the top. Remember Pontiacs got the by-pass, so water still flows and really strong through the heater core.
Heater core will get hot way before the thermostat opens, so there's a lot of water moving through at least that one head.

[steve]

thanks clay ! what is the best method to purge that air if i cant get it out simply by heating it up with the cap off ? after your post i checked the reservoir and there was not a tube going into to coolant in the bottom so it was sucking air after cool-down.

["QUICK-SILVER"]

Steve,
Fix the jug and fill it up like you've been doing. After that it will take care of itself, burb all the air out like it's suppose to and draw back in coolant.

If you haven't already done it.
Clay