Solved Tee Dee Backplate Air Leak

bakergw Thu Mar 25, 2021 2:41 pm

Hi All,

This is a dupe post effectively that provides the end solution I found that works very well and very easily if you are unlucky enough to have an 049 Tee Dee Crankcase and a Kamtechnik Radial backplate where the tolerances or such of the two dont quite seal perfectly and leak air a bit. The following solution is now buried at the end of a long thread and I was concerned people may have viewed it, seen a problem raised and then never see the solution leaving them with an incorrect impression. Note: I have also since tested all of my Tee Dees and all of my Kamtechnik radial mounts where I had a problem and the following solved the issue with all of them.

Sorted out the leak with the seal between the radial mounts and the crankcase, tested and found a very easy and simple solution. I put on a standard 049 reedie crankcase gasket from either of https://coxengines.ca/cox-.049-crankcase-gasket-3.html or http://www.exmodelengines.com/product.php?productid=17598&cat=268&page=2. I carefully put the gasket on over the threads of the kamtechnik https://kamtechnik.com/ radial backplate after cleaning and drying all surfaces and did it up nice and tight. Remounted and tested the engine. Ran perfect! unmounted the engine from my test bed and re mounted the engine on my test bed and ran perfect again! No leaks, no slipping of the plate! Perfect.

I very much like the heads and radial mounts made by Greg at Kamtechnik and have bought over several purchases 10 heads and six radial mounts. Each of my engines has a Kamtechnik head on it and I put killer Bee type cranks in my reedies just to toughen them up a bit, maybe dont need to, but its easier to be sure. I l also like being able to put radial mounts on my Tee Dees at times, especially when I think I might have built something a bit big or heavy for my readie and the Tee Dee sorts it out.

Sorry if this almost dupe is not allowed. I didnt want a solution getting missed and people being left with an incorrect impression. This issue cannot be common or I would have found it on my CEF and Stunthangar searches. Old Bugger

Cheers,
Gary

Ken Cook Thu Mar 25, 2021 3:14 pm

The other solution is to use anaerobic Permatex. It's formulated for aluminum and alcohol immersion and it doesn't harden. It's service removeable and I've been using it for all aluminum backplate gaskets for 20+ years. I bought the little tube which will last years. This works wherever a gasket is needed and only cures where two parts are touching. Therefore, any ooze out is wiped clean and it does no harm internally. This isn't a RTV product so don't confuse it with one due to the name Permatex.

1/2A Nut Thu Mar 25, 2021 4:18 pm

Solution for me is oil the threads with after run oil, hand tighten the radial mount.
Then use two hex head screws to temp the mount on a wood block and rotate the
engine until it bites down snug tight, will be leak free.

Never had one come loose from hand flipping nor elect start. Using a wood block
keeps from stressing the plane / firewall and should be used again when loosening
the radial mount.

Small Cox Logo

dckrsn Thu Mar 25, 2021 6:48 pm

Hey Gary, glad you found a solution. I'm surprised no one ever produced a proper gasket for the application. A nice
thin Teflon one would be great, cheap insurance. You could tighten the "heck" out of it, and still unscrew it without
trashing the backplate. Gaskets for the front and back sides of the carb bodies would be good too(mainly for the aluminum ones).
They do exist, but they don't always come with the bodies. I have used a few different sized copper head shims on the Al bodies with pretty good results.
Bob

bakergw Thu Mar 25, 2021 10:05 pm

Hi all,

I tried many methods of tightening it and even when it was solid and couldnt possibly move it leaked air. This was across several engines and backplates. I tried some filthy performance plus goop as where I went didnt have the anearobic permatex mentioned by Ken which I too consider an excellent solution and used it for many years on my GP race bikes in applications where going wrong would not end well for me. Laughing

The performance plus goop just melted and ran everywhere but it did seal and it least showed me the joint I suspected was the problem. Cleaning the engine after was just great fun. Lol. I wanted to solve it that night and thought I would try a reedie CK gasket and it worked beautifully and I didnt have to tighten it up within an inch of its life for it tow work perfectly.

I will probably use the anearobic permatex as the long term solution, but then again, the gasket is also cheap, clean, quick and easy. Not too fussed. Just glad it worked. :-)

Cheers,
Gary

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