01 duramax cooling system issues

[foxhole]

i have a 2001 Chevrolet silverado crew cab dually 4x4 with the duramax and the Alison. it's at about 210,000 kilometers. was driving down the highway a few weeks back and the low coolant light came on. initially it seemed to be just pushing coolant out the overflow so i replace the rad cap. i also noticed a few drips later on the front drive shaft at the transfer case and bottom of the bell housing and was able to trace it up as far as the exhaust crossover but couldn't actually see where it was coming from.

it keeps blowing coolant out of the overflow and it seems a little weird when i fill it up and bleed out the air. my first thought is head gaskets but i ran 6 combustion leak test in the course of an hour today and couldn't get one positive test. when i left the shop i had filled it and bleed the air and when i got home the light was on yet it hadn't ejected any coolant from the expansion tank and there were no drips underneath, almost as though it burped a big air bubble out and the level went down. I'm almost stumped here, i don't really want to pull the motor and re gasket it without a positive test result for exhaust gasses in the coolant but am not sure what else could create this condition.

[Maxxd07]

When the engine is cold in the morning check the top radiator hose and see if it is hard, if it is take the rad cap off and see if pressure escapes. If this happens then you either have a head gasket problem or an injector cup problem (more likely the cups if you just had injectors replaced). Also since you may have a visible leak check the heater hoses, which I believe are behind the left valve cover. Water pumps also are kind of common on these but I wouldnt believe it would be this because of where you are tracking coolant to, but another thing to check anyways. Of course wind blowing through the engine compartment while at speed can blow coolant anywhere and everywhere. Hope you get some kind of direction from this, best of luck!

[HTX86chevy]

I know this is an old post but I was wondering what you found as a result. I started having similar issues 2 days ago and I cant figure it out. Thanks.

[foxhole]

Head gaskets, was only pressurizing in high boost conditions. Took out rear cover "o" rings and was blowing coolant past the cap. Ran a diesel Exaust coolant test sucker thing to confirm it. Pulled engine, did arp studs, felpro head gaskets and a felpro aux head gasket set and had heads resurfaced. Cost bout 1300 all in. Took a whole weekend though.
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