I have a Kubota ZD221 zero turn with a D722 engine. Discovered oil was leaking into the oil sump, which suggested leaky fuel injectors which I replaced. Oil is still leaking into the oil sump. The manual suggests it could also be leaking from the injection pump. I would appreciate any advice or suggestions as how to proceed.
Diesel leaking into oil pan
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Hammermechanicman
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If the engine has a mechanical lift pump check it for a bad diaphragm.
Thanks, however, although I know little about this particular D722 engine, I have worked on gas engines of all sorts since 1958, and this pump doesn't have a diaphragm.
Hammermechanicman
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Diesel engines will have an injector pump and a lift pump that pushes fuel to the injector pump. The lift pump will be mechanical or electric. Usually fuel in the oil is a bad mechanical lift pump.
Example
Example
how much fuel is getting into the crankcase? If a lot, check engine compression. If a little check engine compression. 450 psi+ is what I like to see. They usually won't run very well once they get much below 400. I think low spec is 380.
If it's low look for valve clearance issue first. Then pull the head and look for signs of bent rods. If they're all ok, pull the pan and look at rings. An oil ring will seal up just fine but if the top ring is worn/broken/cracked, or if the ring LAND is broken/cracked, it will have lots of blowby and never smoke a bit.
ZD21 has an electric fuel pump as I remember, so no mechanical pump on them.
Only other thing would be injection pump related although even that would be a remote possibility.
If it's low look for valve clearance issue first. Then pull the head and look for signs of bent rods. If they're all ok, pull the pan and look at rings. An oil ring will seal up just fine but if the top ring is worn/broken/cracked, or if the ring LAND is broken/cracked, it will have lots of blowby and never smoke a bit.
ZD21 has an electric fuel pump as I remember, so no mechanical pump on them.
Only other thing would be injection pump related although even that would be a remote possibility.
Duhh, of course, I completely overlooked the possibility; I'll check it out further in the morning. Thanks for the Amazon link.
Hammermechanicman
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No, electric pump cant leak fuel into crankcase. Must be something else