SonexBuilders.net

Onex107 wrote: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 spring loaded ones did not work well for me. They were actually quite difficult to install, and the center joint was just one more place to leak.

SonexN76ET wrote: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

I've used 3 sets of those now, and they still leak. So the seals by themselves are not necessarily "the" solution.

mike.smith wrote:I've used 3 sets of those now, and they still leak. So the seals by themselves are not necessarily "the" solution.

The last time I installed those seals I put a little fuel lube on them to try and make them seal a little better; they seem to leak much worse now as compared to previous attempts when I leave them dry. If I pull my heads for any reason, I'm going to install some new seals but leave them dry. I think the most important part of preparing the pushrod tubes for installation is to make sure you stretch them a little so they seal well when you torque down the heads.

For my 2-cents worth, I have found that a small amount of Elring-Curil T Liquid Gasket non-harding sealer works fine no leaks. Having said that I always use new push rod tubes every time and make sure the seam is on top of tube when installing, worth the money. For the sump I use two paper gaskets with a coating of the above sealer on both sides. Have never had a leak. I also use the same sealer on crankcase halves and jugs, again never had a leak. The only place not to use it is on the oil pump.


Regards

Dick
569SX

Another place to check...

Recently I spoke with another AeroVee owner who said he had an oil pump leak because the bolts were just too long and bottomed out. It appeared tight but actually was just snug. He shortened them slightly and leak was gone.

I'm also another "Dry AeroVee" seeker...can't stand a messy firewall forward so I wipe it down after almost every flight, trying to find the sources.

MichaelFarley56 wrote:I think the most important part of preparing the pushrod tubes for installation is to make sure you stretch them a little so they seal well when you torque down the heads.

Amen, Brother Mike! Always stretch the pushrod tubes a little before reinstalling.

Regarding the seals. I always try to run them dry first. If they seem to have a problem sealing, I'll put a VERY thin coat of hi-temp (red) RTV on them and that has always seemed to do the trick for me. In my experience, certain heads have a propensity for leaking, while other heads are just fine. Me thinks it's just variation in the castings and final machining.

As always, YMMV.

mike.smith wrote:

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

My first Sonex .. which I didn't build ... had some seepage around the front bearing by the crank hub. I made the crank
vent tubing a bigger diameter to reduce the pressure and the leak stopped. YMMV.

RT

If you guys figure it out, let me know. Two decades of driving old VWs. Never ever ever ever had one that didn't leak.

vwglenn wrote:If you guys figure it out, let me know. Two decades of driving old VWs. Never ever ever ever had one that didn't leak.

Well I admit my 74 Beetle does mark her territory. But sometimes a VW won't leak oil ... like when it's out! LOL

My Corvair stays surprisingly dry. I use Viton seals on the push rod tubes. Are VW pushrod tubes available in Viton? I use cork gaskets on the rocker covers with Permatex Form-A-Gasket - Aviation No. 3 between the cover and the gasket and a light coat of grease or oil on the gasket to engine side. Keeps them from sticking and many times they'll pop right off and can be reused but still seal completely. That trick should also work on the sump plate. Prop hub leaks (as another pointed out) usually means the engine isn't venting well enough.

FWIW,

Dale Williams
N319WF @ 6J2
Myunn - "daughter of Cleanex"
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
Signature Finish 2200 Paint Job
166.2 hours / Status - Flying
Member # 109 - Florida Sonex Association

I started using these rocker cover gaskets after I accidentally pinched a cork one when installing it and ended up with an oil leak:
https://realgaskets.com/product/valve-cover-gaskets-49/
I've reused them for a couple of years now and don't put anything special on them. They don't leak.

As far as I can tell, none of my pushrod tubes leak. I stretch them to the length mentioned in "How to Rebuild Your Volkswagen Air-Cooled Engine".

Despite this, I still have a mystery leak that I can't track down. The bottom of the engine is always damp with oil and some oil blows out of the cowl at the bottom piano hinge.

I have noticed that the oil breather hose is permeable to oil, so it is always coated in oil. I plan to switch to a better hose to eliminate this as a possible source of some of the oil.