G M 6V53

[sfnz]

does anyone know why these engines crack cylinder heads? have the 4valve heads on turbo intercooled engines x2 and so far have 4 cracked heads. Have replaced 2 heads thus far with 2 more to source and really dont want to ever face this again, is there something in the basic design or something these engines just don't like and makes them do this ?

[Diesel Bill]

A million years ago ,when I used to turn wrenches, The Detroit Diesel dealers had a program that allowed you to turn in cracked heads and exchange for reliabuilt rebuilt heads that were drilled and pinned. This was back in the mid to late 70's. I think the heads were cast to thin and would crack from the injector hole outward toward the exhaust valve seats. Just a theory. Always allow a few minutes for temps to stabilize before shutting down. Not just for turbo engines but all engines. Heat sink enters the heads.

[Lepke]

I ran 6v53 naturals in Vietnam for a total of about 5 years. The engines were ran hard, usually wot or idle. They got rebuilt often, but I don't remember any cracked heads. After that time I owned a lot of diesels and also spent some time welding cast iron. Cast iron cracks when the temperature changes rapidly in a local area. Either it heats too fast or cools too fast.

My theory on diesel engine long life is keeping the oil clean and only using 80% of the hp unless it's an emergency. Especially turbo engines.

I had a yard that did mostly commercial boats and many diesel overhauls. Many were party boats that ran their engines hard. The ones I could convince to keep the hp & temps down got a rebuild about every 10 years. Some of the others every 3 years running the same engines. Most of the time it meant running at 25 knots instead of 30.

[Compass790]

Originally Posted by sfnz

does anyone know why these engines crack cylinder heads? have the 4valve heads on turbo intercooled engines x2 and so far have 4 cracked heads. Have replaced 2 heads thus far with 2 more to source and really dont want to ever face this again, is there something in the basic design or something these engines just don't like and makes them do this ?

Without knowing yr engine my suggestion would be to reinforce the new head where it's prone to cracking, assuming it does it in the same place each time. There is some really good cast-iron welding rods now.
I don't know if there is room to do it or if it's possible to find someone in your area that is a cast-iron welding specialist.
Lepke gives sound advice about rapid heating & cooling otherwise

[Lepke]

New heads or repaired cracked heads will crack again unless something changes in the operation. Demand for more hp and a smaller footprint has diesel makers adding turbos to engines, some not really designed for it. Adding a turbo & intercooler doubled the hp on 6v53 from the natural 210 hp. If you run wot and have pyrometers, you're probably exceeding recommended EGT. A 4 valve engine has all that combustion heat confined to a really small area and only coolant can absorb it. Maybe a bigger water pump">raw water pump from a bigger Detroit and a coolant pump with more blades on the impeller would help. In racing engines more flow is helpful and some reverse flow so the coolest coolant enters the head first.
The only rating I have shows a max of 2800 rpm, but no continuous rating. The 2 are different, especially on turbo engines.