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Water in oil?

M

Megunticook

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I have a 2008 Yamaha F4 which I maintain myself. In May before launching the boat I filled the crankcase with Yamalube 10W-40. Normally I am pretty careful not to overfill it. 99% sure I didn't in May.

The other day I checked the oil level. It was a good quarter inch or so above the full line on the dipstick. It also seemed like it was dripping more than ususl off the stick, like the viscosity was lower. It looked like new oil, no discoloration or milkiness, smelled normal. It was hot that day but the motor was cold.

Is it possible some water made its way into the crankcase? Or would the oil look different?

Suppose it's possible I overfilled in May. But it kind of seems like something got added.

Any advice/experiencesb welcome.
 
Water in the gear case or crank case will emulsify (milky)
sounds like you are getting fuel in the crank case
does it smell like gas ?
 
dark_star said:
Water in the gear case or crank case will emulsify (milky)
sounds like you are getting fuel in the crank case
does it smell like gas ?
Click to expand...

Didn't notice any gas smell. I'll go back and check for that again though.

What would cause that? Worn rings?

Can I use it for the rest of the season (2 more months basically, it's on a sailboat so not heavy use)? Or am I asking for trouble? Wonder if at year 13 this things is ready for a complete rebuild. I've owned it since 2014 and have tried to maintain it well but it does live in salt water 5 months of the year.
 
dark_star said:
Common in 4 strokes that don't get up to temp for long durations
google "making oil"
Click to expand...

OK, read a few things on this. So bad piston rings? Fuel blowing by them into the crankcase? Sounds like I'm ready for a rebuild.

You think I'm OK to run the motor the rest of the year? Should I change the oil now and just keep an eye on it?

So to prevent this I need to run at WOT more often? I deliberately go easy on the thing, generally at half throttle or less I'd say. You figure I should deliberately run the thing hard once a week or so?

Just realized another thing...I noticed the fuel valve was not shut off. I think my son did that about a week ago (I was with him at the time and asked him if the valve was turned off, he said yes, and I didn't check. It wasn't). If the valve is open, and the weather gets hot, is it possible for fuel to expand, overfill the carburetor bowl, leak into the intake, and drip down past the rings?

If the piston rings were worn I"m thinking I would smell burning oil or see smoke.

Ugh. Guess it's time for a midseason oil change. That will be a first for me.

Thanks for advice and info everyone. Please feel free to chime in with comments, suggestions.
 
Last edited:
Suggest change oil and only fill half way up the dipstick.
if the oil level climbs over use, I'd say that's your problem.+
It will also smell like gas.
 
Good news: went out to the boat last night to change the oil and first thing I did was check the level again and smell the dipstick. The level was back down to the top of the full mark and it smelled just like motor oil should smell. Still seemed a little drippy for 10W40 but it's pretty hot here now.

I think what must've happened is that when I checked before I had pulled the motor out of the well to clean the lower unit and leaned it in an upright position while I grabbed my toolbox. The motor slid into a more horizontal position momentarily--it was only down for 2-3 seconds before I stood it upright again but that must've been enough to affect the oil level on the stick.

In any case I think all is well and I learned a few things here--thanks!
 
I was going to suggest was the motor level when you first check the oil level.
If I check the oil on my inboard outboard when it’s sitting on the lift, the oil level is high.
once it’s out into the water & the boat level changes it goes back to a normal reading.
 
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