I've got two 2005 vx110 yamaha waverunners with about 60 hours on each and I keep getting engine oil in the intake that clogs the air filter and severly hampers performance. I was told it was from overfilling the oil but I made sure that was not the case but it still does it. When I detach the rubber intake hose just in front of the mass air flow sensor they run fine. My dealer said these machines don't have a PCV valve, so where is the oil coming from??

David Walters, July 2006

David,
You said that you are sure that you didn't overfill the engine.
Did you run the engine at idle either in the water or with a hose and adapter for 5-6 minutes before checking the oil level?
Over the winter my oil migrated down into the block from the oil reservoir which showed empty. I added oil and started the engine which then bogged down and stalled in a cloud of smoke. Using an electric pump (available at all marine stores), I removed the quantity of oil that I had added and cleaned the plugs and siphoned out any oil left in cylinders. I started the machine and ran it on a hose at idle and then in the water at speed. Very smokey and oil expelled from jet and intake. After the smoke cleared, it ran fine and the oil was back to normal. Intake filter injested some oil, but not enough to plug it...Sometimes you get lucky.
It takes a leap of faith to start the engine when the oil dipstick shows empty, but I now know that unless I see oil in the bilge, I still have plenty of oil.

Stingray359, May 2009