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Discussion Starter · #1 ·
I have a 2005 mxz 500ss and the clutch side cylinder is having a major build up of oil. Compression is good, spark is good, mag side cylinder runs fine. oil consumption has noticeably increased. the oil will build up until the plug will oil foul and causes the machine to put off excess smoke.... any help for a fellow dootalker?
 

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I would suspect the oil check valve. They are on back of the case at the.end.of the oil lines from the pump. Two, one for each cylinder. If you have a vacuum pump, Mityvac or similar, try applying a couple psi of vacuum. The valve should close off. I think you'll find the valve is stuck open.
 

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If you are filling up with oil when the engine is not running, it could also be the crank seal between the water pump housing on the pto side of the engine.

To test injectors you need pressure. Apply pressure through the small oil injector line to each injector. They should hold about 3psi before the release. Some mityvacs will give pressure or vacuum and have a nice gauge built in.

If it holds around 3psi, you can try pressurizing the center cavity housing the water pump. Use the breather hose from the cavity that connects to the oil tank. Try 5psi and see how long it will hold it.

My engine leaked oil into the crank too. It ended up being the crank seal. Not a good idea to run with an engine that fills with oil. It could fill enough to hydro lock the engine.
 

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I would suspect the oil check valve. They are on back of the case at the.end.of the oil lines from the pump. Two, one for each cylinder. If you have a vacuum pump, Mityvac or similar, try applying a couple psi of vacuum. The valve should close off. I think you'll find the valve is stuck open.
X2 on the check valve, had the same issue this year as well, same symptom's as you describe
 

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Discussion Starter · #6 ·
doesn't seem to be getting oil in the base when the engine is shut off because I can out in new non fouled plugs and ride for 15/20 minutes at 100% performance then the plug begins to drown in oil again, so the two check valve are on the base of the engine? the skidoo diagram isn't much to go by... thanks for the input fellas, greatly appreciated!
 

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Those injectors are found rather deep behind the engine. Really can't get much access to them until you pull the air box and carbs.
Find the oil pump, then trace the two small lines going to each side of the engine. It is quite cramped back there.

To replace them you will probably need to remove the engine. They are pressed in and loctited into place so you need to heat them with a torch to wiggle it out.
 
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