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Dave: The V-4 cranking enine on the 70/80/720/730/820/830/840 two cylinder diesels was built by John Deere. It features 2 coils, one for the dash side, and one for the front side. The pistons operate on common throws for each side, and each coil sparks it respective pair of plugs. This means they spark on the compression stroke as well as the exhaust stroke. The carburetors, though simple, like to be kept clean, and have a habit of plugging a passage. They came with original cork floats, and by now the float could be terribly deteriorated and debris could be plugging a passage as well. The oil return passages in the heads are very small, and can plug easily. This could allow oil to roll over down the valve guides and into the combustion chamber. These engines also had a history of being started cold, moved immediately to high speed to start the engine, then shut down before getting a chance to warm up. This led to premature ring wear. The engine shold be allowed to run out of fuel after each start. There is a dash mounted valve for this purpose. Is it the Pony engine that is spitting oil or is the main engine spitting oil ? The big engine generally spits oil when the oil control rings are worn out, along with worn injector nozzles allowing unburnt fuel to exit the muffler in a black drizzle. Just finished going through the pony and main engine on my 70D and mine had all these symptoms. Frank-in-Tallahassee
70D // 855
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