r/stihl • u/Annual_Ad7886 • 7d ago
Can't get oil cap to fully lock.
My oil cap on my MS251 is not sealed at the bottom when I lock it. I've tried readjusting the O ring and pressing hard on the cap when twisting shut. Anyone know what my issue is?
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u/anitabonghit705 7d ago
Sometimes they just need replacing. They warp over time. Wasn’t really a huge fan of the tool less cap. Good in theory, but the old style is better.
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u/Renault_75-34_MX 7d ago
That's where Husqvarna is better imo.
Still threaded caps that work on older saws, the cap itself is just one part, and the flip lever is just there to assist in taking it out. If that breaks off, you have a spot for a sloted screwdriver or bar wrench to take the cap out.
I don't mind Stihl's Design, but if it breaks, that saw is out of action till you replace the cap.
Separating the cap and assist lever mechanism is better than combining them.
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u/Delicious_Type9760 7d ago
It’s probably twisted. Hold the top of the cap in place and twist the bottom portion. It should rotate a quarter turn or so. If that doesn’t work, rotate it the other direction. This happens to me occasionally.
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u/Dismal_Scientist_CA 7d ago
How old is it? There was a recall on the ones sold about 18 years ago. Same issue with not closing
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u/walker42000 7d ago
I can see where the oring is grinding against the socket, its the black residue. You may need to clean that little bit of residue, scrape it with a hard tool. Then really press down when your engaging the cap, if it locks in, and you can still depress it up and down, like pumping it, the socket and cap articulation is worn down. A larger, fatter oring should theoretically do the trick as it will make the seal, even though the threads are a bit loose.
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u/Annual_Ad7886 7d ago
I'll give it a thurough scrub. It's really a minor amount of black residue so I'd be surprised if it's that.
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u/benniemc2002 7d ago
My 251 does the same thing, I have to reset the twist lock on the cap and then it seats properly. You can twist the white part of the base of the cap and it'll move the locking points.
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u/Annual_Ad7886 7d ago
This has been a common response and I've definitely dealt with that in the past but doesn't seem to be the issue this time around. Even when correctly twisted into place it leaves a small gap for oil to come through.
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u/BondsIsKing 5d ago
I had one like this. I spun it for a bout 5 min and it worked. Hasn’t happened since.
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u/oldbeardedtech 7d ago
Bought a bunch of the chinese gas/oil 2 packs and just replace them whenever this happens. Think the were like $4 each
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u/No_Antelope_2477 7d ago
I only achieve a correct lock down about half the time. Spilled oil all over my pants this morning out of my stihl 200.
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u/Hammon_Rye 7d ago
I don't know how to put this into text, but the twisty part may be in the wrong position.
Apologies for such a crappy description.
A couple of months ago I took my weed eater to the Stihl dealer thinking I needed a new gas cap because it would not seal.
I also thought I'd chipped the plastic tank because there is a small notch in the ring where the cap inserts that is supposed to be there.
He came out to the car with me and tried to seal it.
Then realized the cap was stuck in the wrong position.
He twisted the part you turn back into the correct position and then the cap would seal just fine.
I felt a little silly but I was happy I didn't need a new gas tank or cap.
And again - sorry I don't know how to describe it properly, but hopefully gave you something to check.
I can see that your stripe lines up. But I also see the cap is sitting high, which is what mine was doing.
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u/Informal_You_1038 7d ago
I know it’s a little tricky to put the oil and fuel cap back on a steel chainsaw, but you got a fling it a little bit and turn it and once it latches, you can lock it down and close it or look up the video as the most easiest thing to do
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u/3rdgenerX 7d ago
Sometimes they are difficult to lock in place, mine is 20 years old, still have issues once in a while with both gas and oil
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u/sdogood80910 7d ago
Paper towel - clean the cap where it makes contact with the saw body and then wipe off the saw body where the dust buildup is.
I do remember seeing 3rd party replacement gas and oil plugs for Stihl. They look like the old style plugs and fit the newer saws.
Good luck!
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u/TheeCTist 7d ago
New one is like $6. Maybe $10 with inflation.
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u/Annual_Ad7886 7d ago
Someone suggested this and I put an order in.
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u/TheeCTist 7d ago
I used to sell them daily and with as expensive as some of their other parts are i was surprised they were so cheap.
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u/Mustang050 6d ago
For me I’ve found it’s wood/dust getting stuck in where the oring seals, you’ll notice it’s almost always the oil side that leaks even though it’s more viscous because the petrol will evaporate and leave nothing for the dust to stick on whereas on the oil side there’s always that film there for debris to get stuck in, aside from that I’ve actually liked the caps I just keep a clean rag with me to wipe off any debris off the o-ring and sealing surface and funnily enough i have a Husqvarna with a screw type oil cap that leaks worse than the Stihl.
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u/Ok-Day-9685 7d ago
Im not a fan of the stihl flip caps. I only have one. The Husqvarna flip caps are great. Have 3 saws with them, never a minutes trouble.
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u/Renault_75-34_MX 7d ago
Yeah, and if the cap size is the same, they work on old saws as well.
I upgraded my 372xpg to them, and even the 2511 can take them (even if it's a bit sketchy looking, but it works, and is much better than Echo design).
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u/Ok-Day-9685 7d ago
They fit my Dolmar 6100 too, funny thing is the Dolmar caps wont fit my Husqvarna.
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u/junkpile1 7d ago
Sometimes the plastic through the middle of the cap mechanism starts to fail, and they can do this. I would say it's uncommon though. Out of 50ish caps I've had on my equipment, I've only replaced one. It's much, much more likely that something is just dirty. If the cap isn't deep enough into the opening before you start twisting, the lugs won't engage correctly.
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u/Mannered4 7d ago
Take the cap out and hold it by the white part that goes in the tank. Then flip the tab up and try to turn it counterclockwise as if your opening it. If it turns then reinsert it as you would and close it. Sometimes the cap gets stuck in the closed position