Coolant out recovert tank

[forift2001]

I have 2004 6.6 Duramax the coolant is blowing coolant out recovery tank not overheating. Performed combustion gas test it passed. new water pump which had caused overheating. with coolant passing the combustion test o white smoke. 350000 miles any thoughts?

 

[Rockabillyrat]

Don't always believe the combustion gas test. I've had several bad head gaskets on customers trucks pass it. If its over pressurizing the cooling system its probably a head gasket. And since you said you overheated it from a bad water pump. That's makes me think its definitely a head gasket.

 

[forift2001]

Any other test you would recommend?

 

[Rockabillyrat]

Some people install a pressure gauge and drive it. I've seen guys use a clear heater hose and look for bubbles. I just bleed the air from the system with the bleeder screw. Top it off and drive it with a scanner on it. I drive the truck HARD and watch cooling temp to make sure the thermostat is functioning. If its pushing coolant an I confirmed no thermostat issues, leaks, fuel in the coolant, or water pump issues. It's getting head gaskets.

 

[THEFERMANATOR]

Many of the fluids used in the leak check kits will not pick up on a blown head gasket on a diesel. Most likely blown head gaskets(pretty common on LLY's), or injector sleeves if it's an LB7 thats had injectors done recently.

 

[Will L.]

Reaffirming what they said above.

The fluid relies on a high amount of burned fuel to change the color, and depending if the compression is blowing past before the combustion event occurs is one problem.

The other problem is the fuel itself. The more ethanol/ methanol that is cut in the less it changes color. I found the Uview brand combo chemical worked best with new diesel fuel, but their 2 glass section tester sucks.