GASKET LEAKS

I’ve recently read about head gasket leaks. This led me to the conclusion that my Duramax had all the common symptoms.

I have the heads off now, but I am not enough of a diagnostician to determine where or if the gasket is leaking. I can see a gasket break on the left bank, but the right bank had water filled in the exhaust manifold, so water ran out when I loosened the three-bolt flange bolting the manifold to the riser pipe on the RHS. I could not tell if there was a leak on the right side head gasket. Anyway, have you heard of the CO or carbon dioxide test for radiators

to check if you have a gasket/injector leak? I guess it would not have made any difference to me. I had to tear it down to the heads anyway. If someone (like me) replaces the water pump and still has a hard upper radiator hose, they may wish to check to see if exhaust gases are penetrating into the coolant. What I really want to know is: if, theoretically, you had your engine stripped down to the short block and you wanted another 300-500k miles out of it, what modifications would you do? I already have ARP head studs. Would you do anything with exhaust gaskets, crossover pipes, exhaust manifolds, etc.? Thanks for all your help,

Joe Kowalski

Edmonton, Alberta Back in the 1990s I had a 6.2L diesel that had a bad head gasket. We all agreed on it—there was no doubt, but we thought to do a CO test of the radiator gases to confirm anyway. The test turned out to be inconclusive. Since that time, I've not put a great deal of trust in using a CO (carbon monoxide) test to positively identify a leaking head gasket that causes cooling system overpressure.

The Duramax head gaskets have gone through multiple generations in improvements. Just as 6.2/6.5 head gaskets are better today than the originals, I suspect the latest GM head gaskets for the Duramax are better than what these engines were equipped with. Because GM pays for in-warranty repairs, I suspect they have a bigger stake in ensuring that the gaskets they use are the best there are to ensure a long life. Several aftermarket gaskets are available for the Duramax. I'll stick with what GM recommends.

I am a fan of the OE Torque-to-yield head bolts for non-modified, factory-performance diesel engines. The elasticity of the bolts help them to maintain clamping force over the life of the engine. But, if I were building a performance engine, I'd likely install ARP studs because performance engines usually produce a shorter cycle life than stock engines found in a daily driver. A careful preparation of all components (head and block decks), resealing the injector cups (for an LB7), and a careful reassembly should provide a long and useful life for a Duramax driven by the average person (hundreds of thousands of miles). From a longevity standpoint, nothing much else needs to be changed. Careful assembly, clean assemblies, and attention to detail are important. Industrial Injection recently began offering an aftermarket injector cup for the LB7 Duramax that screws into the cylinder head, thus making it more reliable and leak-free. It would be hard not to recommend this addition when completing a repair that you want to last for a long time.