This subject came up after the Continental A75 on my Pietenpol was overhauled and test flights began. The engine was (and still is) bone-dry all over, but during and after flight I was seeing a very fine oil mist on the lift strut and gear leg leading edges on one side of the airplane, as well as on the windscreens. I searched high and low for where it might be coming from, and eventually found that there was oil seeping from the main seal at the nose of the crank. I knew that the seal was brand-new, but a bit of snooping on the Cub and Aeronca sites pointed out that on a new crank, Continental recommends the application of a slightly helical pattern of scratches made with 180 grit emery cloth on the area that contacts the seal, and that had been overlooked on the rebuild of my engine. With the helical abrasions in place, the turning of the crank tends to 'screw' any seepage back into the engine, keeping it behind the seal. The service bulletin is here:
http://www.aeronca.org/ContinentalSB-M76-4.pdf In my case, the procedure was difficult and nerve-wracking because I had to work in very tight quarters between the nose of the crankcase and the backside of the prop flange. Obviously, a split-type seal is required when you can't remove the prop hub to install a new one, and although I thought that would make the changeout easier, it actually made it harder when it came time to get the tension spring installed on the back of the seal. At any rate, I got it all done and reassembled and ever since then the seal and nose have been as dry as Hemphill County Texas (no beer or liquor sold there ;o). Not recommending this for your VW or anything else since the material that the Continental seals are made of may be OK with this and others may not, but if you have a persistent leak around the main seal and are willing to try anything, this approach might be worthwhile. Oscar Zuniga Medford, OR Air Camper NX41CC A75 power _______________________________________________ Search the KRnet Archives at https://www.mail-archive.com/[email protected]/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to [email protected]
