case sealing

[Don]

after 6 race weekends the case is leaking along the bottom seam. I am curious as to what is reccomended for sealing the two halves. I use Permatex Aviation (brown stuff) gasket sealer. Also I stumbled accross a VW aircraft website where they used a strip of Teflon dental floss between the case halves. Does anyone do this?
One other question, for vintage racing (stock VW oil cooler set up) should the oil level still be above the stock dipstick mark?

thanks, don

[satterley_sr]

I use Kuril T for the case halfs. It's easy to work with, cleans up well but it is expensive. I think the vintage engine should be checked the same as a non-vintage. With the engine running on a level surface, oil level should be at the full or a little above. Anything less and there is a danger of spinning a rod bearing under hard cornering.

Dave

[Dietmar]

Don:

Several things come to mind here.
First, to determine where the actual leak is coming from is difficult. The "seam" leak could be from the sump and oil is flowing ALONG the seam giving you a false location, it could be coming from the pump cover and flowing ALONG the seam, it could be coming out the pulley and flowing ALONG the seam, it could be coming from the flywheel and flowing ALONG the seam.
What I am trying to say is that it is rare that the case leaks AT the seam. This happens if the case gets hot and warps- indicated by loose nuts on the case studs ( 13mm nuts) . This is where they did/do use thread (sewing thread will work) to help seal the case. This is an old fix and has been used for years.
If you have a front motor mount as in a D-13, that front mount is rarely ever torqued to 14# and if it is loose, it will allow oil to sneak through and give you the impression of a leak along the seam.And ONCE the oil has gone past the sealer, it will ALWAYS go past the sealer.
As for sealer, anything will work if the case halves are true. I use Gasgacinch because of ease of removal. I might suggest that you clean up the bottom with carb cleaner spray or solvent, jack up the rear of the car as high as it will go and then watch to see exactly where the "drip" is coming from. If it is pouring out(puddles on the floor) - more than likely, you have a warped case (sorry)
Hope this helps.

Dietmar
http://www.quixoteracing.com

[Don]

Guys:

Thanks for the suggestions, the seam does not appear to leak sitting in the garage with cold oil, but only when it has been run. I will wipe it clean retorque the case bolts, start it up and watch for the leak.

One other question if I did use thread will this be a onetime thing (ie will it leave a witness mark on the case) or can the case be reaseembled a second time?

I certianly apprecaite the help.

cheers, don

[Dietmar]

Don:

If it is NOT leaking when it sits, then I DOUBT that there is anything wrong with the seam on the case.
I would look elsewhere.

Dietmar
http://www.quixoteracing.com

[brian]

2x on Dietmar's comments. remember the torque is 14#, anymore won't help leaks and could lead to a stud failure.

[billinstuart]

Never use RTV..anything that has ANY thickness affects main bearing clearance and pinch in the case.

We used hylomar, which will squeeze to 0.00 thickness

I've seen aircraft engine cases go together with silk thread.

[SR Racing]

Don, Been using the Permatex Aviation stuff for 20 years. Never leaks. I also suspect your leak is at the oil pump and just migrating to the bottom of the case. When assembling we put a layer of the Permatex on both sides of the bottom of the case halves. (Only on one side above the crank.) Make sure you put it around all the studs, or it can leak out through the stud hole. (You can also use some RTV under each washer that hold the case halves together. Also it is best to let it set for 20 minutes before putting the case halves together. We also us it on the oil pump around the lip that seals to the case (both sides of the gasket). We use nothing on the plate that covers the pump. There is a small groove in the pump face (and holes in the gasket) that must not be plugged with any gasket compound.

IF your case really is leaking and you did the above, there is a gouge etc, on the case seam.

Re: the oil level. Yep, always check with the engine idling and level. At or slightly above the VW full mark should be fine. Hopefully you have some push rod tube oil restrictors and some windage set up. Otherwise you can empty the sump in long sweepers and under heavy breaking.