Mikeyb

Quick Question: I was changing the spark plugs on a 97 E420 (100,000 miles) I purchased, and found lots of oil on 3 of the spark plugs' electrodes. It dripped from the ends as I took them out of the chamber. I also found some oil inside the spark plug chambers and little on top of the engine block.

This happened on the passenger side bank... as you're looking at the engine, it's spark plugs 1,2, and 4 (from front to back)

Is this a serious problem? Could oil be dripping inside the cylinders from the top of the spark plug chambers?

I don't know how long the spark plugs had been in the engine... they were pretty worn looking!

Please advise!!

Thanks!

ohlord

Blow by from worn cyl walls,run a compression check.Also check that the EGR valve is clean and operating.To much crank case pressure will cause blow by.Lastly the plugs at 100 k should appear pretty good in a clean well running engine,so since you don't know the history,I would make sure the plugs you installed are properly torqued to specs,change the oil and filter,run that compression test,yeah I know it's a ***** pulling the plugs again.Or just live with it for a few thousand miles and pull those plugs to check if it was the egr valve.
ohlord

Mikeyb

Can you guide me to the location of the EGR and a place to purchase a new one? I've searched alldata.com, and 2 online mercedes parts shops, and can't find anything on the EGR valve.

Thanks!

Quadcammer

the EGR valve has nothing to do with crankcase pressure, hence Exhaust Gas Recirculation.

A PCV valve that is stuck may cause some excessive crankcase pressure, but its pretty unlikely.

You may have issues with valve seals or rings. Instead of a compression test, I suggest a leakdown, which will tell you where the cylinder pressure leakage is.

ohlord

that's what I meant and got the parts mixed up,pcv is correct.However you always run a compression test first,to see if any cyl is below spec min. and that all are within spec average.If off by more then specs. state then the more expensive and time consuming leakdown test using compressed air is needed.Start simple and then go to the next step.So I stand corrected on one count.Torque those plugs,check that all cyl are firing properly,to rule out fuel wetting the plugs.And pray that you don't need the leakdown test.
ohlord