SonexBuilders.net

Hello All,

I know others have traveled down this rabbit hole in the past, so I thought I’d start a post for AeroVee operators to offer bits of advice or suggestions on how all of us AeroVee guys can reduce the amount of oil seepage and/or oil leaks on our engine.

I can only assume, but if my engine is any indication on how AeroVees behave, I believe it’s pretty typical for most engines to weep small amounts of oil throughout their usage. On my engine, after a flight that I will have small amounts of oil leaking down my cowling hinge (vertical split cowling), down the cooling exit ramps, and a small amount on the outside of the forward fuselage bottom skin. Nothing excessive but annoying to say the least!

Upon cowling removal I normally see small amounts of leakage around the pushrod tube seals as well as the 6 nuts holding the sump plate in place. I’ve tried different ways to seal those areas up but nothing has made much difference.

I know these engines have loose tolerances and small oil weeps are normal, but for those who have successfully been able to reduce or eliminate oil leaks, I would love to hear how you did it!

Any tips or suggestions would be appreciated! Thank you!

I would like to know as well! Same leak/seep issue at push rod tube seals and sump plate connections.

On a positive at least the lower cowling pin never needs lubricating. My push rod tubes thankfully have never leaked, don’t ask me how. I do though always have a slight drop of oil accumulate from the rear main/ cam plug area and also the oil pump area has a small issue along with the large case plug near the oil pump. Each one is small but I try to ignore them. Whenever the cowl is off I just give it a small wipe with a rag.

MichaelFarley56 wrote:... as well as the 6 nuts holding the sump plate in place. I’ve tried different ways to seal those areas up but nothing has made much difference.

I put a dab of high temp form-a-gasket on each copper washer before I put them over the studs. That also helps to keep the washers in place as I put the nuts on. That has generally done the trick at that location. If the sump plate itself is leaking around the perimeter after I drop the sump and clean the screen, since the gaskets down there are made of paper, I sometimes need to tighten the acorn nuts just a tad after the first few flights.

As for the push rod tubes, the first time I built my engine, no leaks there! After subsequent maintenance involving removing and reinstalling the push rod tubes, not much luck stopping the weeping. The last time, I added a small amount of high temp form-a-gasket on the seals at both ends. That has helped some, but has not eliminated the weeps. I'm careful to go light on that material to prevent it from squishing and entering the case.

I'm pretty sure I have a slight weep from the prop hub, too.

All in all I burn/leak very little oil. Last time I flew to OSH and back (nearly 2,000 mi and 20 hours) I used about a half to 2/3 quart of oil. But I AM the plane with a permanent oil stain on the pad under my cowl. :-(

I tracked down a few of the oil leaks on our Aerovee: the pushrod tubes (new seals fixed that), the oil cooler bypass plate (O-ring had been cut when the plate had been mounted), the breather tube attachment plate (the "inside" one of the four bolts that hold it in place had stripped), the rear seal (probably due to excessive axial play damaging the seal, replacing that) and the prop hub (we're changing to a Force One hub which has a seal there so hopefully that will not be a problem in the future.)

It wasn't much, but enough to get everything covered with a film of oil that collect dirt. And makes you really dirty every time you work on it. I hear it's possible to make them not leak...

Onex 107 went through the same number of small leaks. My fix for the pushrod tubes was to buy the two piece aluminum tubes that are threaded in the middle with a lock nut. You can replace them without removing the heads and you can tighten them in place until the leaks stop. I did use gasket seal on the threads. The threads on the oil pan plate can be stopped by acorn nuts and copper washers. The paper gaskets on the plates on the top of the engine had to be redone with gasket cement. I don't route my crankcase vent oil back into the engine. I built a version of an oil separator, using a Ball jar, that works very well and I measure and remove all vent oil. That's an old Cessna commandment. "Thou shall not put contaminated blow by oil back in the engine." It's got something to do with Nitrous Oxide mixing with moisture and forming acid. Measuring all oil, in and out, I can account for all but about 8 oz. in 25 hours, which I assume goes out the exhaust. I think the blow by oil volume is a good clue about the health of your engine. Just broke 200 hours and counting.

I tried, unsuccessfully, to make a pair of pliers that could expand a standard pushrod tube after it was installed. There are pushrod tubes that are spring loaded also. Bill Larson used those. I'm not sure how well they worked. The threaded alum. tubes are infinitely adjustable.

The paper used for the sump plate gaskets is, at best, a thicker version of a coffee filter. I custom make the gaskets for my buggy from gasket material I get at NAPA. Not a drop from that area in 25K miles. A sealer called Gaskacinch can also be your friend in the quest.

My Aerovee is now mostly dry. I get a stray drip once in a while but it is very minor. In 200 hours of flying I seldom have to add any oil between 25 hour oil changes.

To stop the push rod tubes from leaking I use the EMPI white silicone pushrod seals. No leaks at all using these seals on the pushrod tubes. SILICONE PUSHROD TUBE SEALS, dune buggy vw baja bug https://www.amazon.com/gp/product/B0046VRW8C/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

To stop the sump from leaking I use Fel-Pro OS21625 Oil Pan Gasket Set : https://www.amazon.com/gp/product/B000C2EE3K/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

To stop the valve covers from leaking I use Fel-Pro VS26062R Valve Cover Set: https://www.amazon.com/gp/product/B000C2GIF2/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

These have worked well for me.

Jake

Mine is totally dry! Of course I have yet to run it, or even put oil in it.