1966 stock 122 sedan

For the past year there has been a lot of oil blowing by the gasket at the oil filler cap. The pcv valve was removed, cleaned with plenty of carb cleaner and verified working -- hey, what's that black stuff all around your mouth? Timing was checked, points cleaned and adjusted, fuel mixture checked -- all with no improvement. The car lost a half quart of oil every 500 miles or so. Rings maybe? The engine bay was covered in a fine spray of dirty oil within 150 highway miles after many attempts at cleaning. Very frustrating.

The guy who finally resolved my timing gear situation told me that diaphragm in the fuel pump was torn and oil was coming out of the relief hole on the bottom of the pump. This was a spare Pierburg pump that was installed following some hard start issues (turned out to be a non returning choke).

The original glass top AC pump was reinstalled. No more oil spray in the engine compartment. No more blow by out of the oil filler cap! I can understand the lower part of the engine staying clean now. I am not so sure why changing the fuel pump stopped the oil from blowing out the top. There is not even one drop of oil along the valve cover gasket after 1000 miles and best of all very little oil consumption. :-)

Very strange but very nice.

Joe M in WV

If the diaphragm in the pump is torn, gas drains into the crankcase and overfills it with a thin oil/gas mixture. This will blow out from every possible place. It also makes the car run rich, as the intake is getting gas fumes through the PCV system instead of just the normal crankcase fumes.

Sounds like an oil chage is needed before you run it again. Besides being a bad lubricant it's likely to have loosened up a lot of crud. Let the dropped oil settle so you can check it.

Would it be better to drain the oil cold and undisturbed? Normally the car is warmed up first before changing oil.

Thanks,

Joe M in WV