gas in oil

[flipp19585901]

got gas in oil in 4 stroke what could it be ,,

[staylor]

If the motor is relatively new than you may not have run it enough to seat the piston rings. Until they wear in you'll get some blow-by past the rings and put some gas in the oil. Check your owners manual and be sure to follow the factory break-in exactly as listed. Some Yamahas have had problems with excessively hard rings that take many hours of running to seat. If you're past break in and the rings haven't seated, then hard acceleration from idle to top end followed by a high speed run for a few minutes will help to seat a stuborn ring- this may have to be repeated many times before the ring seats. You should change the oil if it becomes contaminated with gas and you notice the oil level creeping above the full line on the dip stick. Eventually when the motor is old and worn out it will again start to have blow-by and put gas in the oil- but this would be after many years of service.
Doug

[bob1]

I had some gas in my F150 and I changed the oil and filter. I have read to run them hard to help this situation.

Bob

[yarcraft91]

The FC-W certification process for marine 4-stroke oil requires that a certain amount of gas wind up in the oil during the test and that the oil maintain adequate lubrication when that happens.

My 2006 50 horse EFI Merc has gas in the oil at the end of every season. Each year, there is less "excess oil", so apparently the rings are seating very slowly.

[Flip Silverlake]

Any gas the in engine oil is not a good thing, but you will find that all 4 stroke engines will have some gas in the oil, even your car. There are a couple of reasons this happens. The main culpret is running the engine cold. I had a 1974 GMC Jimmy that I only drove a short distance to work. I had to change the oil once a month becasue of the gas that ended up in the crankcase during the winter time. The engine never came to full operating temp and the choke was on for most of the trip. The same issue is with 4 stroke outboards. Early and late year operation in colder water makes the engine run cooler than it should and you end up with gas bypassing the rings. Heavy short duration throttle run ups will cause this issue also, like when your trying to get your buddies kid up on skies and he hasn't a clue how to stay up!

I remember talking to a Suzuki dealer, that sold motorcycles, and before they would deliver a bike they would take it out and run the guts out of it to try and seat everything. That was on that 4 cylinder 1000cc bike.

I wouln't get to excited about it, but would keep an eye on your levels. If you find it over filled it might be worth a change, you could change the oil and not the filter, that should not hurt as long as you would change the filter on the 100 hour interval or once every season. The comment on running the motor under a heavy load is something that will help, but make sure you don't lug the engine for a long time becasue that could damage the valves. Remember your car runs some where between 190 to 210 degrees when its warmed up. Your outboard never gets close to that heat range.

[brn2fsh]

I have an 04 9.9 mercury bigfoot kicker on the back of my Tracker. When I picked the kicker up from the dealer, we told me about a condition know as "Making oil". Until the rings seat, fuel is able to get past them and into the oil. He told me to run the crap (Vary the rpms and keep it under a load) out of it for about the fist 8 hours. Well ,it took alot more than 8 hours. What I finally did was just to use it as I wanted , but check the oil level after each trip. If it was up more than 1/8 " on the dipstick, then I would change it immediatley. Took most of a year for the rings to seat. Works great now. Hope this helps.

Rob

[erickrwill]

I would have to agree with Silverlake but my problem was slightly different. I had a yamaha 9.9 that would have gas in the oil every year early in the spring time but not in the summer. After changing the fuel pump and listening to the dealer tell me that that will happen when trolling at very low rpms (when it didn't happen the 1st 3yrs I owned it), I found that the thermostat was stuck open and would activate the automatic choke pumping too much gas in. The engine couldn't warm up to the proper temp in the spring but would when the water warmed. I changed the thermostat and never had the problem again.

Good luck

[ziemann]

Keep in mind that this is a fairly common issue. It is certainly not a crisis but can be unsettling. Here is a really nice explanation from another web site. This FAQ is most commonly referenced on this topic.

http://forums.iboats.com/showthread.php?t=158085

[bob1]

Good article!

[yarcraft91]

Keep in mind that this is a fairly common issue. It is certainly not a crisis but can be unsettling. Here is a really nice explanation from another web site. This FAQ is most commonly referenced on this topic.

http://forums.iboats.com/showthread.php?t=158085

Thanks for the link. I had not seen this thread before.

Hmmm- my motor that "makes oil" sits on a lift over the water all summer...