2006 F250TXR Oil Issue

[Doc Z....]

I have a 2006 Yamaha F250TXR that runs great w/o any issues. I noticed the STBD motor uses some oil...about a quart in 60 hours and when I checked it there was condensation in the cap. It was a milky deposit which is not on the PORT motor. The oil looks fine on the dipstick and when I change it there was absolutely no water in the oil. The motor now has 540 hrs and I have had them since 120 hrs. This started last year so I compression tested the motor and all the cylinders were fine. I also pulled the lower unit to see if there was any exhaust corrosion and it looked OK (posted some pics). I changed the thermostat to see if that was an issue and it still has the same problem. This motor also runs about 20 degrees cooler than the PORT motor at WOT. 183 vs 203 degrees. Does anyone have any idea on what the issue is? Maybe a pinhole in the exhaust creating steam that I cannot see?

[Keithbaja]

A qt in 60 HRs ??? That sounds Scary !! Get a (reel) manual and ck oil pump discharge and flow rate..is that at 60 Hrs of idle. Where the mix is 100 to 1. Holy Molly

[99yam40]

A qt in 60 HRs ??? That sounds Scary !! Get a (reel) manual and ck oil pump discharge and flow rate..is that at 60 Hrs of idle. Where the mix is 100 to 1. Holy Molly

So you are drinking heavy again today?
This is not a 2 stroke

[Keithbaja]

I don't drink anymore. Sorry,, I'm not perfect...

[zenoahphobic]

No, Keith has been good for awhile.

Back to OP, you might not see water, but it is getting in, evidenced by milky under cap. Running cooler may also suggest water in combustion chamber.
You need to find a leak, could simply be splashing into air box (small amount).

If water ingress into combustion camber, it could go past the rings into the oil, and that can compromise bore oiling and ring sealing, allowing in turn, oil to pass up into the combustion chamber more than it should leading into excessive oil usage.

[Doc Z....]

No, Keith has been good for awhile.

Back to OP, you might not see water, but it is getting in, evidenced by milky under cap. Running cooler may also suggest water in combustion chamber.
You need to find a leak, could simply be splashing into air box (small amount).

If water ingress into combustion camber, it could go past the rings into the oil, and that can compromise bore oiling and ring sealing, allowing in turn, oil to pass up into the combustion chamber more than it should leading into excessive oil usage.

Thanks........even though the compression test was good....150lbs in all cylinders I am going to have to leak it down. Hopefully I can get another 3w out of it without any catastrophies by keeping up with the oil consumption. It's also burning oil as it smokes way more on startup and idle but not so much on WOT or I just cannot see it.

What bothers me is 2 Yamaha mechanics have said that is normal and not to worry.

Another Mechanic suggested the crankcase evac was not working properly creating too much crankcase pressure.

[Doc Z....]

Update....after using 2 qts of oil per day for 7 days for total of 15 qts the motor suddenly stopped using oil for 4 days...no smoke...no oil use...nothing...clean...then today began smoking again. I'm pretty sure at this point this would not be an oil ring or valve guide at that would not have fixed itself so I'm thinking maybe a faulty PCV Valve?? Anyone have any experience with this?

[Doc Z....]

I'm pretty sure this whole problem is related to the exhaust issue so I ordered the Kit.....I'll update on what I find.

[Doc Z....]

Update. I have not done the exhaust yet because so far I have run this motor in Salt water for 1000 miles over the last 2w and it has not used a drop of oil. Does this make sense to anyone? In the Hudson river this motor was using 2 quarts every 30 miles and not not a drop? I am utterly confused as to what could be the issue other than maybe a PCV valve that was stuck sucking oil and now its freed up. If anyone has any ideas please chime in.

[Keithbaja]

I recommend you pull the plugs and inspect. All plugs with oil signs is a telltell. Like faulty PCV system. If 1 or 2 plugs is a good sign of oil control piston ring. That or oil is leaking outside of engine

[Doc Z....]

I recommend you pull the plugs and inspect. All plugs with oil signs is a telltell. Like faulty PCV system. If 1 or 2 plugs is a good sign of oil control piston ring. That or oil is leaking outside of engine

Yes I changed all the plugs last month but on my last trip home 66 miles the motor did not use any oil at oil as it was the weeks before........the Port side was clean but dark. The STBD plugs all look like they have a little bit of rust on them which is why I thought the exhaust was the issue.......when this was occurring the oil cap would have a ton of cream on it after 10 + miles....I mean a lot. Now after 1000 miles in salt water and no oil use the plugs look pristine........no where near what they looked like when the motor was burning oil and there was obviously steam in my crankcase to cause the cream in the cap.........again....I am puzzled as to how this fixed itself and I do not believe salt water fixed it.

[Keithbaja]

Cream under the cap is water,,, plain and simple... I would replace the Therms and clean plugs.. Run her like u always do.. Then inspect.. Have you heard of a highspeed shutdown... That can show a lot of things that are easy to miss...BTW,, bring two extra plugs with you. You never think you could drop s plug in the drink,, let alone two... It happens

[Doc Z....]

Update July 2024:

This problem seems to have fixed itself. I'm pretty sure the PCV valve was stuck open sucking oil but it has not used a drop in the last 400 hours now..........go figure.