View Full Version : Yamaha 4 stroke gas in oil

08-01-2006, 12:31 PM
I have a 2006 Yamaha 4 stroke 60/40 jet.Has anyone yet found out how / why gas is getting into the oil. I've used the Yamaha 4 stroke oil and have approximately 40 hours running time.I was told to remove gas line after each use but this did not help. I have changed the oil 3 times now because the oil was "overfull". Does anyone have an answer? No one is talking at the dealer (I believe they have on clue).

Gary B.
08-02-2006, 02:56 PM
"They SHOULD have a clue by now.....My old 1985 model burnt up/froze TWICE with major rebuilds in order. The factory paid most of the second one because I screamed. Then, it happened to a friend of mine as well; the engine froze up in Neah Bay just before a trip down the coast on a sail boat.

In spite of this, I bought a new one in 2000. Just this season it, too, started "making oil". The dealer suggested I change thermostats because the engine may be running too "cool" and gas goes past the rings.

However, my fuel pump just quit, too, and they say that a malfunctioning fuel pump can push gas down into the oil. I think Yamaha engines are GREAT when they are running properly, but they have a design flaw of some kind, for sure.

I am debating whether to have the dealer fix it, or to try to tackle it myself. That is why I looked at this website in the first place.

Deal with it soon; this is SERIOUS, potentially.

Gary B."

Gary B
08-02-2006, 02:58 PM
PS. My previous message should have included that this is a 9.9 four stroke high thrust outboard

Gary B.

mark marlow
08-07-2006, 01:05 PM
My 2000 115 is at the yamaha dealer now and has been for 4 weeks for this same problem. last week they said they thought it was the thermastat letting it run to cool also--I see post for this same problem but no one has ever had an answer-yamaha must know this happens and someone should have a good answer. Mine is overfilling the crank case also...i am at the mercy of the dealer now as i have know other answers--also slow service.