[JDVKLA]

First the ski has about 30 hrs or so. This is our son’s PWC. Ran great Saturday until weather ran them out of the lake. On Sunday they ran about 4 hrs in the afternoon with on problems. Today after about 2 hrs he noticed the ski was slowing. They stopped checked the suction screen found nothing, then pulled the seat and checked the oil. Found water in oil. Towed the ski back to the dock and came on home.
I removed all spark plugs. All where a light tan color, #2 had some black carbon but general the plug was tan in color.
Reinstalled spark plugs. Ran engine to change the oil until it was clean. No sighs of milky oil (8 gallons).
This is the first and only problem we have had with this ski.
Any ideas on where to start?
JD

 

[~mike]

I'm confused, first you said you saw water in the oil but didn't see any milky oil while changing it? Try throwing a new set of plugs in it. The 4 strokes seem to be pretty sensitive to weak plugs.

 

[tymeshare]

After pushing 8 gallons of oil though it(wow)..how did it run?..

Maybe the two are not related?..or..maybe you have lost a head gasket..

 

[JDVKLA]

Mystery solved.
Thanks for everyone’s input.
Removed the engine from the ski, thinking water was entering in engine’s oil system through the oil tank. Removed oil tank and pressured tank to 7lbs. Gauge was steady. Looking over the engine the only other place water was at a higher pressure than the oil was at engine block and at the cylinder head cooling water jackets.
Pressure the block found water leaking around the plug that is in the head, Yamaha part # 60E-12483-00-00. Two dollar o-ring failed.
JD

 

[Leoaa777]

Which plug is this? I think I may be having the same issue.