Gas in oil, 4 stroke Yamaha

[Surface Interval]

Today while I was checking my oil level in my 250 4 stroke Yamaha, I notice the oil level had gone up or was higher then normal. A friend told me I may be getting fuel/gas in my oil. Any ideas..

 

[Bryan 2530]

Bad T stats can cause that if they are not allowing the motor to heat up properly.

You sure its gas??

I assume you did the basics like level the engine, pull and reinstall the dipstick, etc.

 

[Parker23]

Bad T stats can cause that if they are not allowing the motor to heat up properly.

You sure its gas??

I assume you did the basics like level the engine, pull and reinstall the dipstick, etc.

Ditto.

 

[DaleH]

2 things:

On 4-strokes, the level can appear to rise if the temp you're now checking the oil at is appreciably higher than when you filled it.

Or, you over-filled it and didn't give time for it to all settle before you took a reading.

There are some Yam motors that "make oil" where gas bypasses the rings and weeps down into the sump. This is caused buy the owners babying the motor and not running it hard enough to have set the rings properly during break-in.

 

[HOTPURSUIT]

Two things
I had it happen to me when I fist purchased my used Parker. I was doing alot of trolling in early spring, still very cold out. The oil level went up and I could definitly smell the fuel in the oil. found both stats to be corroded open, changed the stats problem solved

But if you are checking your oil level after the motor has sat for a few days it will definitly appear alot higher than it does if you were to check it shortly after you have stopped the engine.

I would suggest to start the engine, let it run a bit. turn it off wait 5 min then check the level, keep checking it this way, plus what Bryan suggested so that you get a consistent reading.
Good luck Mike

 

[Dennis C]

I had the same problem with my F225. Changed the T-stats and everything is OK

 

[Surface Interval]

Hi guys,

Well it looks like I'll be ok. I think some oil worked its way up as the engine had been tilted up before I had checked the oil and had been sitting a few weeks, just like HOTPURSUIT said.

A lot of you guys talked about the T-Stats I'm not to sure I know what one is or where it's located!

Thanks for all the help.

 

[DaleH]

Small 'pockets' on top of each cylinder bank. There are websites w/ schematics to show you where ...

 

[HOTPURSUIT]

There are two, one one each side, go buy two new ones, once you know what they look like its a big help in finding them. There are few things that will need to be removed to get to them,make notes or take pics so you know how it goes back together camera phones are great for that . Patients and about two hours will get it done.

 

[Brent]

should be in the ballpark as shown in
http://www.simyamaha.com/category_s/1986.htm

 

[Surface Interval]

Hi all,

Well, I finally changed out my Tstats (thermostats) and yes I did it myself. I thought I was getting myself into something I wouldn't be able to get out of, but it was very easy at the end. Took me about an hour to do two motors and each Tstat cost me about $28.00, best part no labor cost. The one on the right is one of the new ones.

 

[Brent]

Thumbs up

When we changed the thermostats we replaced the pressure release or poppit valve too

 

[DaleH]

FWIW when 4-strokes 'make oil' the 1st thing dealers look at is new t-stats for engines running cold.

 

[Surface Interval]

Hello again,

Well, I took the advise of my fellow CP members and changed out the poppet valve as well. I think the hardest part about this project was removing four of the eight apron bolts. The poppet didn't look bad, but it came out and new one in. Both engine poppets did look the same. Thank you all for all the feed back. I love it when members post pictures so I took a few. The poppets look different in the picture, but they are the same. The new one is on the left.