Detroit D40, D50, D60 Excessive Crankcase Pressure or White Smoke


Problem: This is a blow-by issue caused by either:

Fuel, air, and moisture forced past the rings into the crankcase

Contaminated and diluted oil in the crankcase

Solution: Use Stiction Eliminator and Diesel Extreme to free up both sides of piston rings. If the piston rings are worn out, they will need to be replaced.


Some blow-by is normal on any diesel engine. This is because the combustion pressure is just too great for the piston rings to hold completely.

Excessive diesel blow-by can be caused by piston rings that are sticking in the bore. One of the ways to check if blow-by is too great is to put your oil filler cap upside down on the filler hole. If the cap gets blown off, there is too much pressure in the crankcase.

Diesel blow-by can be caused by piston rings that are worn out. A cylinder with worn out rings will have low compression and will likely cause a misfire. These piston rings need to be replaced.

If you have any questions about blow-by engine treatment, feel free to contact one of our diesel experts.

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