Waxy Substance Under Valve Cover

ErickBaker · October 21, 2006

I'm working on a 2005 F-350 with about 65,000 miles on the clock. It came in for white smoke and coolant leaks. I diagnosed it as headgaskets and during tear down I noticed a waxy substance caked on the inside of the valve covers. I originally thought it was from water and oil mixing but the oil doesn't appear to be milky. I've never seen this before and was wondering if any of you guys have run into it.

FYI, the EGR cooler also appeared to be leaking and the truck was over loaded. I was just curious if there may be something causing this (i.e. problems with the crankcase ventilation system) that I need to adress before putting the engine back in.

Keith Browning · October 22, 2006

Eric, you may not have water mixing with the oil but you do have excessive water vapors in the crankcase gasses. The water and oil can mix as a vapor and condense on the internal metal surfaces or the engine creating that film. I have seen it once before myself and it is strange.