Cam Plug Leak

[Titanium Cranium]

I pulled my motor originally thinking the oil leak was the common rear main seal. It did appear that the rear main seal was leaking a bit, but as I degreased the back of the engine thoroughly, I found a pinhole sized leak in the cam plug. I unfortunately have the old plastic/rubber type cam plug. Because it seems absurd to tear apart a perfectly good running motor to replace a failed paper thin plastic plug with another likely inadequate one that still isn't serviceable without unnecessary invasive repairs, I decided to try a different approach. I decided to fabricate an aluminum cap that seals the existing plug and folds around the flanges of the case halves to increase the contact area for adhesion as well as create a far more reliable barrier to contain the oil. I attached it with the same high temp RTV that the rear main seal called for and then applied a liberal amount around the edges of the cap I made. It still retained clearance (about 2-2.5mm) between the cap and the bolt heads on the flywheel. I'll be doing several hours of test flying directly above the field and pulling my cowling to see if my idea works out, so I'll report back as to what the results are, hopefully in the next week or 2. Here are some photos of what I found and the cap I made.

[kevinh]

One other idea (if this one doesn't work). See if you can find out what sort of plastic was used to make those plugs. Many plastics can be dissolved and reformed with the appropriate solvent. So for instance, if the plug is ABS you could brush on a little bit of acetone to soften up the area with the leak and reform it as leak free ABS.

[Titanium Cranium]

I got the plane back together and have about 3 1/2 hours on it between the ground run time and the flight time. So far the cam plug cover I made is holding and things are looking good. I feel confident flying away from the airport vicinity at this point, so I'll post another update as to how the cam plug cover holds up after a bit more time in the air.