My '99 E300 has had excessive blowby for the past few months. Under hard acceleration/high rpm it would blow the dipstick out and pump oil everywhere. Ziptie the dipstick in place and it would blow oil past the filler cap. Crankcase pressure (measured today with gauge plumbed in place of the dipstick) would spike beyond 10 psi as soon as the revs got near 4,000.

Found a post on a UK website where a guy used crude water injection to clean combustion chambers and free the rings. I copied the simple setup that the guy there used - (a washer fluid pump misting water through the crankcase breather hose entry point ahead of the turbo). In my case, I just used the contents of the washer reservoir (water/methanol in there anyway..).

Drove about 40 miles highway, 2500 - 2700 rpm with the pump/mist setup running. Pumped about 5 liters of washer fluid through the engine. Problem solved, no excessive blow by. Crankcase pressure stays at or near zero even when running uphill at or near redline. Let is sit overnight, changed the oil and filter this morning. Problem solved.

Obviously don't want to continue putting water in ahead of the turbocharger. I'm going to add a water/methanol injection kit that will come on at high boost to both of the E300's. Hopefully this will keep the problem (no doubt caused by running WVO with our 2 tank conversions) from recurring. Should have added benefit of reducing EGT's on the kid's '98, which is chipped.

Still don't know why the 606 engines have this problem when others don't, but it looks like water or water/methanol injection can overcome it and keep this experiment on the road.