Engine/Transmission (1994 - 1998) Air Bound Cooling System

[vssman]

Have any of you experienced trapping air in the cooling system after changing the thermostat? If so, how did you get it out? So far, my only thought is to put in a flushing tee in the heater hose or try jacking the front end way up. The jiggle pin doesn't seem to want to jiggle with a big air pocket behind it (I think).

 

[illflem]

All of the air has always ended up in the radiator for me, I just add more coolant after the truck has been driven awhile.

 

[The patriot]

What Bill said.

When I had a mercedes diesel they had a procedure to follow. Take the cap off the radiator, and run the engine @ about 2K RPM for a minute or two. They called it "burping the system".

Eric

 

[vssman]

Yeah, I tried that several times. I guess I can try the flush tee in the heater hose.

 

[Berrigan]

VSSMAN



Ive had engines almost overheat because the new t-stat had air behind it and did not see the heat of water and open.



And I agree the jiggle pin whether the type in the t-stat (1st gen) or the type that threads into the housing (2nd gen) dont work that well.



What has worked for me is to remove any fitting or hose on the engine side of the stat before filling with coolant. Some engines have a plug about an inch Engine side of the stat. Others have heater hoses that can be removed. Anyway open it up then add coolant and this will vent air until coolant comes out. Then put plug or hose back on and finish filling. works for me!!

 

[Berrigan]

One more thing, the service manual says the jiggle pin only opens when the engine is not running. So when it sees pressure due to a spinning water pump it closes and wont vent until the engine shuts down. I think they or a good idea but kinda useless in the real world. A nice factory installed petcock would be the best.