Crankcase breather & oil traps

Combustion pressure that slips past the piston rings has to leave the crankcase, and it carries oil mist with it. The oil trap returns that oil to the sump and sends the cleaned gas back to the intake. When it clogs, crankcase pressure rises and pushes oil out at the dipstick tube and the shaft seals - a leak that is often blamed on the seals themselves.

Oil traps and their repair kits, breather housings, vent elbows and the bleeder lines that connect them are listed for MAN D08, D20, D26 and D28 engines. Line lengths and bends differ between engine variants, so the number on the old pipe is the safest starting point.