Oily lower plug problem

[zephyr]

My M20F lower plug #2 has a continual problem of getting oily and after a few flights I get a mag drop due to it being fouled at runup. The cylinder has been taken out twice (second time under warranty) and IRANed and given a clean bill of health but it hasn't solved the oily plug problem. No other cylinder is a problem but when I take the plug out I can usually pour out half a dozen drops of oil out of the plug. Any ideas what solution I should check next.

[robert7467]

Well, could be because your rings are not seated. Are you babying your engine? If so try the following:

 

Clean the plug

Maybe try mineral oil (talk to your mechanic)

Run the engine hard, and don’t baby it.

If the rings get seated, switch back to detergent based oil.

Go full power on climb, and climb at 120mph instead of 105 to keep the engine cool (I have a m20c, so yours might be a little different)

Also, if you have a long taxiway you can try a rolling run-up to minimize running at low RPM on the ground (might get a little brake wear, and some people on her might not recommend it, but it also works great for busy airports, an instructor taught me this in long beach)

 

Consult with your mechanic before you take my advice. This same thing happened to mine, and I did the above and it worked.

 

On my plane at around 3500-4000 I started running it at 25/26 and 25/25 and it solved the problem.

[robert7467]

ohhh, and before you guys start bashing me on the rolling runup, I am well aware of the dangers of doing a runup while taxiing, and how you should pay attention to the taxiway, so its not a common practice for me, and my taxiway is over a mile long, and wide and I did it to avoid running it for a length of time on the ground to help break in the cylinder.

[zephyr]

Robert, thanks for you input. I think I'll try the flying at 25/25 and see if that helps. It hasn't been 4 or 5 hours since the cylinder was worked on. The mechanic didn't think I needed to use the mineral oil just for one cylinder.

[robert7467]

Gotcha.. Run it like you stole it! Our engines were run at full power to determine TBO, just keep an eye on your oil temp and open cowl flaps if needed.