Oily spark plugs

rudymantel · Post by **rudymantel** » Sun Aug 29, 2004 12:54 am

Both spark plugs in my right rear cylinder were very oily. Obviously, there's a problem, possibly with the rings. Cylinders have some 700 hours since new. Haven't yet done a compression test but at the annual, in Feruary, all compressions were very good. Would appreciate any thoughts / suggestions.
Rudy

lowNslow · Post by **lowNslow** » Sun Aug 29, 2004 5:21 pm

Most likely your valve guides if the compression is still good.

AR Dave · Post by **AR Dave** » Sat Oct 15, 2005 10:49 am

Pulled the lower plugs yesterday to find out why the left mag was dropping 250 rpm's at run up. All 6 were wet with oil.
I'm going to clean them up, turn the crank 2 dozen times to pump out any residue, and reinstall plugs.
Compression was good a year ago. Plane's been sitting too much.

Rudy what did you find?

rudymantel · Post by **rudymantel** » Sun Oct 16, 2005 2:17 am

My compression was good, so it was probably the valve guide. I "solved"
the problem the simple but costly way. I installed 12 new Champion iridium spark plugs and haven't had a firing miss since. I don't recall the exact cost but they were expensive, the figure of $60 each comes to mind.
Rudy

AR Dave · Post by **AR Dave** » Tue Oct 18, 2005 3:26 am

Stayed with plan - cleaned em up and reinstalled plugs X-crossed upper / lower for even wear. Ran up the engine to about 1300 rpm (normal about 1700) and checked mags. All seems good for now! Will put the cowling on and fly for an hour in the morning. If the mag check stays good (50 rpm drop), then I'm not going to worry about it.
I don't understand how the plugs would get oily by non-use. Seems to me it would have to be a mechanical problem like rings or guides?

AR Dave · Post by **AR Dave** » Tue Oct 18, 2005 9:34 pm

I've definitely decided I have the best flying plane in the world. It sure was fun making those circled touch-n-goes the am. Well, the Right mag was dropping to much and the left was good this time. Since all the lower plugs were moved to the top yesterday, it didn't take long to find the bad plug. The maintenance shop had a gap in work and asked me if I wanted to do my annual today. So we're in a full blown annnual. Engine checked out good. Looks like everything will be done by tommorrow.

PS - With me (220 lbs) and topped off tanks - it only climbed about 1000 fpm from ground (400) to 3000 ft.. Last yr with Randal, his son, I, & full tanks, it was about 750 fpm.. Hoping that replacing two plugs will help!