Yamaha 4-Stroke Making Oil

[Woodnaut]

I have a 2006 Yamaha 90 HP 4-stroke (F90) with about 100 hours. It has suddenly started making oil. Any experience with this? Probable cause and remedy?

[boats.net]

A engine running too cold, check thermostats. A engine over worked, too heavy of load or not propped to run in operating range of 5000-6000 rpm's. A problem with fuel system, like stuck float in vapor tank or a compression problem can cause a it to make oil.

[Dennisg]

HI All, Please forgive me, but I have never heard about a motor "making oil". Would someone please explain to me what that means?
Thanks, Dennis

[jonp]

I would be interested as well "making oil".... Now I will be really impressed when they start laying eggs ....

Making Oil

With Oil at $70/barrel I'm glad that I bought a Yamaha!!! Their sales will really pick up if this get's out. I'm heading down today to buy a few more!!!

I have a friend with a 25 hp fourstroke. Its a 05 mercury model and he is having this same problem. He went to the dealer he bought it from and they told him that several four strokes come back doing this. He was told they believe he doesn't run it hard enough, not getting it all the way warmed up and to much *****ing. He runs his most of the time *****ing and when he's not *****ing its usually real short trips so maybe the dealer is right. When he changed his oil i was told he could smell gas in the oil. He bought this motor to ***** with and thats why he wanted fuel injection and a four stroke so its kind of disappointing, but anyway maybe this helps.

[Woodnaut]

Making Oil

The term "making oil" refers to the condition of an increase in oil level in the crankcase. For example, a leaking head gasget can cause water to get into the crankcase. In this situation, the oil is visibly discolored and might appear white or "milky".

Gasoline can also enter the crankcase and mix with the oil. Blowby (around the piston rings), a leaking fuel pump diaphragm, or in some cases vapor canister/breather hoses can cause this to occur. The oil viscosity will drop, and as one member noted, it will reek of gas. Im my case, the Yamaha Technician seems to have nailed the cause of my problem - my engine was overpropped. This causes the engine to work harder and therefore increases blowby. Increased blowby can "carbon up" the rings which adds to the problem. I changed back to my original prop (which increased engine RPM and decreased load) and used some Mercury Marine "Power Tune" (to reduce/eliminate carbon on the rings). I still need to get a few more hours of operation to confirm the effectiveness of these changes, but so far things look much better. -Woodnaut

[antiguan]

yup, my F225 started "making oil" at 1250 hours and turned out to have water in it. the exhaust plates were bad on all three motors and the one with water in the crank case had two broken vavle springs too. Engine never ever ran higher than 6000 at any time and would cruise at 44-4700 most of the time at work. Anyway, making oil isn't a good thing. lol hey by the way, where do i find a part number for a gear cable?

[boats.net]

antiguan
If you are needing a remote control cable(shift or throttle cable) then the part number is MAR-CABLE-xx-SC, replace the xx with length cable needed.

[antiguan]

thanks again.