Stihl MS290-310 Case Hole

[Wood Doctor]

A friend said his Stihl MS 290 is leaking bar oil while running and most if it appeared to be coming through this threaded hole in the case:

The IPL parts diagram shows nothing but I have seen this hole on others, including the MS 310. I elected to drive a short M5 machine screw into the hole to see what would happen. The leaking stopped. Question I have is, will that interfere with bar oiling? What is that hole doing there? I don't think the MS 390 has it. Please advise and TIA.

 

[Creaky limb tree care]

That's the oil tank vent,plugging it will cause a vacuum resulting in oil pump not pumping!

 

[Wood Doctor]

That's the oil tank vent,plugging it will cause a vacuum resulting in oil pump not pumping!

That's what I was afraid of. Now, is there a compromise? I wonder how we stop the leaking oil coming out and still provide a vent for pumping action? I have not seen this wide open hole on the MS390 or the more recent MS291. Stihl must have figured something out.

 

[5000+]

Not a vent. It's plugged port used to connect oil passage to bar pad. You can plug it but don't go too deep or you will block to passage to the bar pad.

 

[Nutball]

Usually there's a red plug melted in there. I saw it on a 290 and 291

 

[lwn9186]

Stihl makes a grub screw to replace the missing plug. Part number 9134-381-1230.

 

[Wood Doctor]

Usually there's a red plug melted in there. I saw it on a 290 and 291

Seems pointless if that is the case. The screw I sunk in was about 1/2" long. One has to wonder why Stihl wanted that hole there in the first place or left it there even after they decided it wasn't needed. Another engineering goof? Operation successful (pump works), but the patient died (bar oil all over operator).

 

[5000+]

See post 4, not a goof.

 

[Nutball]

Maybe that's where the drill entered to connect the passage, then block the left over opening

 

[Chainsaw Addict]

This is the grub screw. Brother in law MS 310 leaking same.. I'll try to get part number. Ed

Sent from my SM-G965U using Tapatalk

 

[Chainsaw Addict]

This is the grub screw. Brother in law MS 310 leaking same.. I'll try to get part number. Ed

Sent from my SM-G965U using Tapatalk

OOPS saw part number above. Loctite it

Sent from my SM-G965U using Tapatalk

 

[Nutball]

Find the thread size and one may be found at the local hardware store.

 

[Wood Doctor]

Seems like the short M5 machine screw I used should work also. Thanks guys. I'll check to make sure the bar is getting oiled OK.

 

[cus_deluxe]

i just nipped the end off a sheetmetal screw on one for a friend, lightly threaded in with a little sealer, no problems a couple years laterp

 

[raumati01]

I built a saw out of NOS parts and that was screw was missing, like the other said I put a grub screw in there .

 

[Creaky limb tree care]

I stand corrected!