Oil Pump Gasket

[arlen]

I took the cover off of my oil pump to check it out. Everything looks pretty good, other than a thick paste of oil/water mixture on everything. There is minimal wear on the cover, and after reading about lapping the cover, I will definitely do that.
My question is regarding reinstallation of the gasket. Given that they seem to have a history of failing, do you put the new one in dry, or use a sealant of some type?
I thought it might be a good idea to use a hi tack aviation gasket compound, but thought it might add too much thickness and muck up the clearance with the gears.

[Gary Dotson]

More like mucking up the gears with goo. Install it dry.

[Aircactus]

I used 440 wet or dry sandpaper and some silicone as a wetting agent to get my cover back close to tolerance. Used a figure 8 pattern and it took the better part of 3 - 3.5 hours of lapping. (Break it up into smaller sanding time periods or your shoulder may regret it.)
Although I had two gaskets to use, one was sufficient. No sealant. Just the gasket. Added some lubriplate to the gears and reinstalled.

I've read many stories on might work before I started. This worked for me.

10+ hours now and good oil pressure and no issues.

Air

[SamsFarm]

I used 440 wet or dry sandpaper and some silicone as a wetting agent to get my cover back close to tolerance. Used a figure 8 pattern and it took the better part of 3 - 3.5 hours of lapping.

Next time, try something in the 120 grit range to get you close, then switch to 220 to finish.

You should not have to go past 220.

Your body will thank you for it!

Try wd40, it works excellent!

[Gary Dotson]

I agree! The gasket surface needs a little texture to properly retain the gasket. If it's real far off, I start with 80 grit dry paper, only use a lubricant on the final cut.

[arlen]

I got it all lapped. That was more of a job than I bargained for! I would say at least 10 hours of lapping. It went pretty quick except for about a 1 inch stretch on one edge.
They don't make emery paper like they used to. Even the 80 grit dulled pretty quickly. I went through about 6 sheets, but probably should have used twice that many.
Reminded me of my childhood lapping the aluminum valve covers on our Lycoming radial aviation engines. My father was a crop duster and we had 3 airplanes that he worked the devil out of. We usually did a major overhaul on at least 1 engine every year.
Us kids did allot of valve lapping, valve cover lapping (there were 18 valve covers on each engine), gasket scraping, and parts washing.

[Aircactus]

One year follow-up on oil pump lapping and replacement gasket, no sealant. Maybe 30-35 operating hours for the year and still excellent oil pressure, even when engine fully warmed up. Straight conventional 30W. Extra effort to lap the pump cover into a close tolerance but worth the effort.
\\
Air

[ricky racer]

Thanks for the follow up! We all learn from others every day.