250 SHO

Most engine oil will have a gas odor if it has been run for a certain amount of time. Engine oil has emulsifiers so that it can mix with water. It takes a large amount of water to make the oil have a milky appearance. When auto engines intermix its usually an ethylene glycol water mixture and less is required to make the oil look milky.

It very well could be water and gasoline that is contaminating the oil. The air to fuel ratio is such that there is no liquid fuel entering the cylinder. Its vaporized and mixed with a lot of air, maybe 13 parts of air to one part fuel. The engine would have to have a tremendous amount of blow by to have a appreciable amount of fuel enter the crank case. I believe even if that were the case there would still be 6 times more water. Although the boiling temp of water is lower then some of the components of gasoline which can be as high as 400F so there could be a slight fuel build that never boils off.

If the humidity is 50% and the average air to fuel ratio is 13:1 then there would be 6.5# of water going through the engine for every 1# of fuel.

Has anyone performed a leak down test on one of the high oil building engines?

I wonder if burning ethanol gas vs non-ethanol gas has anything to do with this. The reason I ask is I have a SHO and I am not having any issues with mine "making oil" but I have never ran any gas through mine with ethanol in it. I'm curious as to why it is affecting some motors and not others. I have also been running ring free in mine since the day it was put on my boat. Mine was bought in march this year if that makes any difference.

I run the 10% ethanol gas in mine and I have not made oil in any of my three SHO's I've had and own now. I know very early on there was some thermostat tweaking that needed to be done to get the motor temps up. I wonder if that would be related to your case. I know that is suppose to be non-factor now but who knows. Maybe some got out with faulty thermostats. I'm a bit fuzzy on specifics referencing initial TSB last year. Just a thought. It's easy to get caught up in generalities but your best solution is to take it to an authorized Yamaha Master TEch if it was me. There are not many of these guys around. Usually one to three per state but that would be my route I'd take. I would only take my motors to someone with those credentials. They are highly specialized with Yamaha's in general and be sure they have had additional training with the VmaxSHO. http://www.bassboatcentral.com/smileys/thumbsup2.gif

Yeah I had the tsb done and a new thermostat put in to get the temps up some. After this weekend I will get it in. The production of my motor was 5/2010.

At least I have 4 more years on the motor.

Pain in my &^%&* !

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by leo13 &raquo;</td></tr><tr><td class="quote">

If the humidity is 50% and the average air to fuel ratio is 13:1 then there would be 6.5# of water going through the engine for every 1# of fuel.

Has anyone performed a leak down test on one of the high oil building engines? </td></tr></table>

Wouldn't there also have to be significant blow by for water to be in the oil?

ive seen nearly every weight of oil out there with water contamination and they were all milky . now aeration is another story but seems like after it sets for a few days the level would drop back to normal which reminds me the system could be holding pressure because when you first pull the stick there isnt any oil on it then once reinserted oil is present on the stick hmmmm. i too had the making oil issue but once i lowered the level down to half way between the two holes i never made another drop

Maybe not significant or excess, but enough. The crank case ventilation system is constantly removing water from the crankcase. The increased volume occurs when the production rate is greater then the removal rate. In general aluminum engines do have more ring leakage then cast iron. Usually the manufactures compensate for this with higher capacity crank case ventilation systems.



<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by NCFatBoy &raquo;</td></tr><tr><td class="quote">

Wouldn't there also have to be significant blow by for water to be in the oil?</td></tr></table>&lt;br /&gt;&lt;br /&gt;
Modified by leo13 at 3:56 PM 6/22/2011


Modified by leo13 at 3:56 PM 6/22/2011