Stihl MS 250 chainsaw

[Don32]

I have this saw and for some reason the bar oil continues to leak when in storage. I have change the "O" ring on the cap and is still leaking. The caps are the ones that sit in a groove then turn a 1/4 of a turn. I have never cared for these. Anyway, I have gone as far as sitting the saw on a plastic container to see where the leaks is. When I perform this test, of course, no bar oil comes out. But, as soon as I put it in the case, it leaks like crazy.

Before I tear this apart I'm looking for suggestions of where to start.

Thanks.

[topsites]

Hopefully someone has a better answer, but have you tried
asking your dealer this question?

[Don32]

they would have to look at it, of course, for an hour labor. I'm trying to fix myself and was hoping someone had a similar problem and was able to fix it. I have heard that when cased the oil that is in the chain rail will sometimes leak back into the plastic case, but the amount mine leaks is much more than what the rails would hold.

Thanks in advance.

[SLR]

What if stored on one of it's sides?

[ricky86]

Some saws will leave a small puddle. Pressure from temperture changes, relation of pump to oil feed hole, and residual oil from bar and chain. There is a small vent for the oil tank near the bar mount area on the saw. Is it draining the tanks?

[Don32]

unfortunately had a large puddle in the case. Last night I stored the saw without the bar/chain on and no leaks. So now, why would having the bar off change things??? Does anyone have a schematic of my saw that would show this vent and hoses etc. I'm wondering if when the bar is on it is engaging the oil supply????

Thanks,

[jkilov]

On stihl homeowner models the oil tank is a part of the plastic housing or a molded insert. The bar studs often screw into the side of the oil tank plugging the holes. That's the first lace I'd check, the tension on the bar stud might be forcing a small crack to open. Next look for cracks at the front or bottom of the saw.

Best thing to do is give the saw a thorough clean, add 2-stroke oil in the oil tank. The lubricating properties are sufficient to use as bar oil so don't worry. The die will make it easier to locate the leak. Depending on size it can be sealed with a touch from a heated screwdriver or use of epoxy glue / polyester set.

[Don32]

Thanks, jkilov. I have also added pics. Can you show me what you are describing? Also, the pic of the bottom has a rubber grommit of some sort. I'm wondering if temperature may affect this rubber piece when stored in the garage??? This is confusing. I would think if there was a crack it would leak all the time. I'm guesing it has to be bar related just not sure where???? No leaks thus far as it sits on a paper towel on the work bench.

Thanks,

[jkilov]

Also, the pic of the bottom has a rubber grommit of some sort.

That is the lower part of the oil pump body (2nd pic) and it's made from nylon. The tube to the right is the oil pick-up line and enters the oil tank. It's seal may be leaking (2). The upper left of this part contains the pump chamber. A small shaft/piston with a notch revolves in this chamber doing the work.

Looking at the 2nd pic I can't tell if there's dirt on it or a hairline crack (1). If so, the position at which the pump piston rests may stop or allow a leak, would make sense. Anyway, take the pump body off by removing the screw. See if it's the culprit and get new a new assy. at the dealer. There's a small ring on the piston, don't loose it.

A lot of saws leak oil when old, some so bad you can only fill up on work sites. So think nothing of it.

[Don32]

Thanks jkilov,

Gotta love being able to import digital pics. Thanks for all your help. I'll try the oil pump assy.

[Don32]

Ok, I took off the oil pump assembly. In the first pic there appears to be what looks like a notch. Is that suppose to be there? And, in the second pic, the area just above the rubber washer is not perfectly flat. Is this suppose to be like that. Hopefully, this is my problem.

Thanks,

[ricky86]

The part your holding is the connector. It goes from the pump (the silver part in pic 1) to the oil feed hose. Assemble, clean area with brake cleaner, fill oil tank with Stihl bar and chain lub with a small amount of auto trans fluid (because its red) and let it sit. If the "leak" is in that area, it will show up pretty clearly. You really don't want to remove the pump unless it's not working.
Wrong viscosity oil will cause larger than normal puddles.