160909 Carter Canyon Road, Gering, Nebraska 69341
Many early John Deere 'E' engines develop annoying oil leaks around the magneto area. Also, most have some leakage of oil around the mains. I have been able to solve or greatly reduce these problems on several 1 HP and 3 HP engines and will pass on information on the procedures I have used. I can't guarantee complete success, but I have been very happy with the results.
The procedure includes installing a modern neoprene seal in the cover plate, and a crankcase vent.
I use seal #1-196-089 M1 purchased from my Massey Ferguson dealer and machine both the cover plate and the magneto gear to fit (see drawing). Both machine jobs are done on a small metal working lathe. I center the plate using the existing hole for reference and center the gear surface from the gear center hole using a mandrel (also easily produced on the lathe).
A four jaw chuck gripping the toothed part of the gear could be used, but there is a danger of breaking a gear tooth due to the odd number of teeth. I prefer using a mandrel in the gear center hole. Some gears have enough asymmetry in casting to cause the machined flange to become somewhat thin, however, I believe most, if not all, will finish satisfactorily.
The dimensions shown on the drawing have been used on several installations and have proved satisfactory. A light press fit of the seal to the plate is desired. Be sure to measure the seal diameter before machining the plate and allow approximately .002' interference. Install the seal with the lip inward and oil the rubbing surface of the gear before assembly to the engine.
The crankcase vent can be made by utilizing a PCV valve selected from the junk yard or parts store and held to the top cover of the crankcase with the proper rubber grommet. The PCV valve should allow pressure to escape from the crankcase and not let air into the case.
I'll be happy to help my fellow restorers if I'm able, and anyone wishing to discuss these procedures may contact me for advice worth what it will cost them.