Dave B

Could I pressurize the air outlet side and check the coolant ports for air leaking.

We have had that problem also. This only does it at higher rpm. We also replaced the compressor although it doesn't mean it isn't that again. Is there a way to test under load.  

On 11/12/2008 at 10:12 PM, Gambi80 said:

I had a coolant-push problem last summer...ended up being the air-compressor head gasket being bad and pushing compressed air into the coolant. Started with being random amounts at random times, then into full blown inability to hold coolant.

Anyway, try bypassing the air compressor coolant lines when you're at idle.

On 11/12/2008 at 10:12 PM, Gambi80 said:

I had a coolant-push problem last summer...ended up being the air-compressor head gasket being bad and pushing compressed air into the coolant. Started with being random amounts at random times, then into full blown inability to hold coolant.

Anyway, try bypassing the air compressor coolant lines when you're at idle.

We have a 2001 e7 427 rd688s, it has very low mileage on overhaul. Everything but crank replaced. It pushes coolant when at rpm. Doesn't push at idle. Does not over heat. We replaced air compressor,stat, radiator, fan and clutch, water pump, checked all hoses. Truck runs great. Found no hydrocarbons in antifreeze. It seems like a flow issue as it doesn't pull all the antifreeze back when cooled and pushes below the temp that would open the stat. Any thoughts would would be greatly appreciated.  If I can't figure it out in going to put it on the dyno. Trying to avoid that. Thanks for any help.