C15 pushing air (video)

Some trucks have air powered heater controls, older Freightliners are one, that if they leaked, it would leak air into the coolant. Another test you can do is disconnect the air compressor discharge or outlet and retest to see if the air compressor is leaking into the coolant.

 

Ok, buy one of those coolant system pressure testers, install it, and do not pressurize it. Run the engine to full temp and watch the pressure increase. Normal system pressure is only 7-10 psi. If that engine is building beyond 15 then something is wrong for sure. If not, rad caps do go bad, the seals do fail or wear out, even the neck on the coolant reservoir can become cracked or warped and cause coolant to leak out and appear to be pushed out by the engine.

 

Seeing the amount of bubbles, I bet $$$ head gasket or cracked head. Before you start tearing it down take the pipe off that connects to precooler and look in there. If you see any white residue it is leaking, I doubt it will cause the amount of bubbles I saw but it is alot easier to fix than a teardown!!

 

Opps,

Opps Sorry it doesn't have a precooler. Refer to my first sentence.

 

Shut truck off.... remove rad cap to remove all pressure from system. Then reinstall rad cap. Start truck and rev up 3 or 4 good times letting the engine jake each time. Shut off truck and go to rad cap and slowly open. If it has pressure it is 99% the head gasket or a cracked liner