Gas in Oil F250

[JZGrowler]

I recently purchased 2007 Kingfisher with F250 with 280 hrs on it. When I purchased the boat oil level was at about 50% mark on dip stick markings. Had approx 30 hr on oil and looked clean. Motor starts instantly, no smoke will run up 6k RPM and never misses a beat.

I only had the boat in water for about 2days before taking in to have bottom paint redone during that time I ran it at cruse for about 2hrs 3800- 4200 and played at low RPM and idel for apox 2hrs learning the boat. After pulling the boat the oil level was a good 2 inchs above full mark and was clearly gas not water in the oil . I have changed the oil and winterized the boat but I’m now worried about the condition of the motor and how gas is getting into oil.

I have read a bunch of posts on the internet about decarbonizing (seems strange to me on modern fuel injected engine that, that much gas would get by rings), Fuel pump ( makes no sense to me how that would cause gas to get in oil), Thermostats ( I see how that causes water in oil but not sure how gas) . Fuel injectors (seems most likely to me if a leaking fuel injector let gas in cylinder after shutdown.) From all the articles I have read I could not find one that said what fixed the problem.

My current plan is to change Thermostats, add the Yamaha ring free Stuff , and to run it fairly hard for a while and see what happens..

Sorry for the long post, but looking for anything else I should look at before taking to dealer or doing leak down test?. Im going to worry about this all winter, but can not get it into a dealer for check before spring because of some travel.

[DennisG01]

I'm not an expert, but something here sounds fishy. Not you - but possibly the seller. Strictly from what you wrote, it sounds like there was a known problem with the engine... the seller drained some of the oil to make the sale. Although they didn't do that good of a job since they drained it down beyond the normal "full" mark. But that should have made a lightbulb turn on, too.

Did you buy this from a reputable company? Any type of warranty? Did you get a mechanical survey done on it? Was there an explanation (did you ask) for why the oil was low?

[TownsendsFJR1300]

You may want to post the model #. It may be needed.

With that much fuel in there, there's a definite issue somewhere

From what I've read here, likely the fuel pump(s) is leaking fuel into the crankcase.

Someone will chime in with a more definite answer..

[JZGrowler]

The motor is a F250TXR SN 10210121J I think a 2007

I actually don’t think the seller tried to pull something over on me, but I sure could be wrong on that. I did not find the fact that oil was at 50% of the hash marks alarming so did not ask. With that said as painful as it may be, buyer beware, and I’m now the owner, and trying to diagnose what the issue is. So looking for any incite on most likely areas to focus on for gas in the oil, or anyones expertise in this area.

I have the manual on order, but trying in mind to picture how a fuel pump can get gas in the oil sump, but other post on the web have suggested that so I must be missing something would not be the first time that is for sure.

Thanks all

[rodbolt17]

we WANT the oil to be about half way up the stick.
we DO NOT want it at the top of the stick.
I get them in all the time overfilled due to folks not knowing how to PROPERLY check the oil and WONT read an owners manual.
to properly check the oil.
warm the engine up.
tilt motor at least 1/2 way up,clear the trim pins.
wait about 5 min.
trim engine to level,NOT all the way down.
remove the dipstick.
wipe it off.
insert the dipstick fully and remove.

two main ways we get fuel in the oil on the F250 is overpropped and running to cold.

that motor must be able to turn 5800 RPM with the days load, not yesterdays load.

[JZGrowler]

Thanks for the input Rodbolt. It will jump on a plane and hit 6k quicker than any boat I have been on, I was surprised that it seemed to get its best fuel economy at about 3.8K, less RPM than other 4stk I have run.. The temp gauge shows just over 150, but Im sure that is at one spot so will investigate further. One of my plans was to change thermostats just out of general maintenance seem like a no loose try. I was very surprised last year when a Suszuki DF70 I have was getting water in the oil, and a thermostat replacement fix it. Would be a real long shot to have the same bug, but worth a try.

Thanks for the input

John

[rodbolt17]

your numbers all look good.
next time its in for service,or sooner, have a cylinder leak down test run.
takes about 30 min or so.

[DennisG01]

we WANT the oil to be about half way up the stick.
we DO NOT want it at the top of the stick.
I get them in all the time overfilled due to folks not knowing how to PROPERLY check the oil and WONT read an owners manual.
to properly check the oil.

Interesting. I probably would have been one of the ones who overfilled! Who would of guessed it should only be half way - I mean every other dipstick I've ever checked (and happened to read the manual... ) said it should always be to the top of the hash marks. Thanks for the clarification, Rodbolt!

JZ - I also slightly misread what you meant in the first post. I thought you meant it was only halfway up the stick (between the bottom tip and the full line), not half way into the hash mark. I agree - half way into the hash mark area, I wouldn't of thought anything about it, either. Regardless, sorry for the misdirection.

[boscoe99]

Here is what Yamaha sez. Nothing at all about trying to get the oil to the top of the mark.

Now what they should have also said is that the motor should have been tilted up for several minutes before lowering it to take the oil level measurement. If that is not done, and if someone tries to fill to the top of the dip stick scale, they are almost guaranteed to overfill the motor.

Trying to top off the oil level is a lot like torque. If just right is OK then too much must be even better!



Now here is what Mercury says about oil levels in the Verado:

[Solarman]

250txr, 07, fuel in oil

Is it possible, that the unused fuel from fuel rail, returning to the float chamber, now relaxing from being under pressure, might be expanding/ overflowing into the breather tube assy (especially if the float needle valve is hanging open too much.) Allowing fuel into oil? maybe add section of clear tubing to breather tube to visually check?
Just a thought?

[boscoe99]

The "making oil" (fuel dilution really) is a known issue. Things that contribute to it are piston rings not being seated, thermostat(s) stuck open, too much propeller pitch, operating in very cold water, idling for long periods of time, etc. Yams run very, very rich based on my tests of three different models.

However, many, many Yam four stroke owners who started tilting their motors up before checking the oil level and/or draining their oil, and who only filled to the mid point of the oil level scale, miraculously were pleased to discover that their making oil issue disappeared.

[DennisG01]

Boscoe - learning as I go, here. Thanks for posting that. Do you happen to know if this "doesn't need to be to the top of the hash mark" thing is common to all 4-stroke outboards? They are something I'm not too familiar with, yet. And, I wonder why? Inquisitive minds, you know?

[boscoe99]

Boscoe - learning as I go, here. Thanks for posting that. Do you happen to know if this "doesn't need to be to the top of the hash mark" thing is common to all 4-stroke outboards? They are something I'm not too familiar with, yet. And, I wonder why? Inquisitive minds, you know?

Yes, I believe that it is common to all four stroke outboard motors.

Why? Because it is all too easy for oil to be left inside the motor itself, and if this is not taken into account of, then if and when adding oil to the full mark there will be too much oil in the engine.

An automobile engine is configured so that the pistons run straight up and down or up and down at a slant. Any oil that is on the back side of the piston will drain into the oil pan when the motor is stopped. Any oil that is on the vertical webs that support the crankshaft will run into the oil pan when the motor is stopped.

An outboard motor has the crankshaft positioned vertically. The webs that hold the crankshaft are horizontal (act like shelves) and the pistons are moving horizontally. If an outboard motor is left trimmed in then oil collects behind the pistons and on the horizontal shelves that comprise the webs. Say someone checks the oil. It appears low. He adds oil to get it to the top of the dipstick scale. There is now too much oil in the engine.

So, the procedure is to tilt the motor up to force the oil to run back to the pan. Then, just to be on the safe side don't try and top off the oil. Just get it somewhere in the middle of the dip stick and all will be well.

Here is a snippet from Yamaha about oil collecting behind the pistons and causing oil smoke at engine start. Another common issue that appears in outboard motors only. And radial aircraft motors for you old guys.

[DennisG01]

That makes perfect sense. Thank you for taking the time to give a detailed explanation.

[almetelo]

Thats explain why some motors smoke a lot at start up.

I've seen that question here on the forum a bunch of times