It seems like a blown head gasket because the combustion pressure inside the cylinder goes into the coolant and causes bubbles in the cooling system anong with excessive heat- over heating. It also leaks coolant into the cylinder causing white smoke and hard starting. As the crack in the block gets worse so do the symptoms.

 

IMO, All GM built 504 turbo diesel blocks will get it eventually. If you have the GEP blocks with the 5 digit julian date code for the engine you are ok [when the military took over production and improved a few things]

My 1998 had it replaced under warranty GM Major guard. That was at 60-70k miles. I purchased the truck with 79k and had another #8 on a "fixed" GM block at 138k-ish miles. And I babied the engine and did all the maintenance to the letter.

I had a dealer drop in a new replacement engine [GEP Optimizer 6500] and all in the costs were around $14,000 out the door. About 55 hrs of labor, the engine, and a few new other things [new radiator, etc that I had done].

Telltale signs are white smoke, overheating conditions, loss of coolant, etc. There's usually no advance warning.. its just.. bam. It's there.

IMO, if I get another h1 down the road, I'd look for a 6.5 Non turbo with the 4 speed transmission. More reliable and honestly it's not that huge of a difference between a 6.5 N/A and a 6.5 Turbo.. they're both slugs. Transmission is a bigger factor IMO.

 

Is the non turbo engine not affected by the 8 cylinder crack? I had mine (turbo) replaced to a non turbo engine on my H1 by a previous owner and i was wondering why he went with that engine.

 

6.2 and 6.5 N/A engine blocks are a different casting number and are not subject to the #8 issue.

I've known people who went back to 6.2/6.5 for wheeling. If I had to do things over again I would have gotten a 6.5 non turbo with the 4 speed.