Onan 4000 Microquiet crankcase oil leak

jdfrye wrote:
here is the update and how I fixed the leak
https://youtu.be/hCclRkP-PiM

This is from an old hand on engines: You found out a ratchet isn't a hammer, try to keep that in mind. ;)

Hopefully, you have the balancing gear indexed correctly. The video shows some paint on the gear but indexing marks are typically forged into the gear.

Did you adjust the valve lash when you connected the rocker back into place? This is done with feeler gauges and a service manual will usually have the whole process. Most small engines, the valve lash is adjusted while engine cold. YMMV.

Those reed assemblies use a piece of spring steel for the operating reed. They can and do lose tension from being worked. It is typically about the metallurgy and not about debris interference. There should be no significant debris inside the engine and the video showing a spotless timing gear space (where you replaced the front cover gasket) shows exactly that.

I have a lot of respect for Onan, Onan/Cummins and even larger Cummins diesels. I've worked on them all and even with some of their quirky design features, they seem to have great durability.

If you want long engine life and good operation, I'd suggest to follow the manual's service descriptions, religiously. Onan/Cummins seems to shine in engineering and manual service description.

If I had to diagnose the cause of your oil leak, it would be the reed valve and someone torquing on one bolt that holds the cover plate. Next time (hoping there is no next time), apply some light silicone to the mating surfaces and use the correct torque wrench to tighten the case bolts.

Good work on stopping the oil leak!