I looked at friends 05 duramax today and is pushing coolant out of overflow tank.also coolant is discolored.truck has 130000 miles and runnes great with no power issues.no white smoke on startup or when running.when radiator cap removed with engine running coolant level begins imidiatly to overflow but i dont see any bubbles.He thinks it's a head gaskets.He just replaced water pump 2 weeks ago and that didnt fix the problem.Are these engines known for head gasket/heads problems or could it be that egr cooler is maybe bad? any help or sugjestion is apriciated at this point.
Thank you in advance
Vlado

 

sounds like your getting cylinder pressure into your cooling system, so HG would be a good thing to test for.

what color was the coolant, is there oil or black crap all in it now?

 

yea there is black crap on the wall of recovery tank but not mixed with coolant.coolant level was low when i looked at it and i topped it off,but wall of tank is definitly black. i am trying to see if these engines are known for certain issues before i tear heads down,because they look like PITA.how can you test HG? i can test for combustion leaks in coolant system but wouldn't egr cooler problem give you the same results?how do i rule out between the two?

 

that sounds like a HG, you can compression test it and see whats up, they sell diesel compression tester kits for 20 bucks at harbor freight.

and yeah doing the heads its a pain, ive done them before

 

sound like a head gasket to me too, best friend had a 05 dmax with about 125k on it when his started doing it, i think it is a more common prob on the 05's

 

Are you having any temperature issues? Overheating or lack of engine warm up? How does oil level look? Have any indication of water in it?

 

This truck has no problem whatsoever other than coolant discoloration and pushing out of overflow tube