stud bolt turning on MS250

[Bibbyman]

Mary's back with the saw. Unclear what the problem was.  Said there was a burr or something.  Sharpened the chain.   Total charge ... $2.00.   

[MAF143]

This old issue just got me last week.  My MS250 was due for a clean up of the bar and chain, I like to take the bar off every 3rd sharpening or so to clean out the oiler groove, check for burrs, and flip the bar.  The rear stud just turned with the nut and after some choice words since the Stihl shop is closed for the weekend.  It is still under warranty but I'm pretty self sufficient most of the time.  I do not over tighten the bar keeper nuts.  I snug them firmly with just thumb pressure on the Stihl supplied tool.  I went ahead and tightened it back in and was trying to figure out how to hold the stud to loosen the nut...  There is nothing to grab onto since everything is all covered up with the bar, chain, and cover in place.  So I got out the impact wrench to try it.  It spun the nut right off without turning the stud. After getting the bar off, I took the stud out pretty easily by double nutting it.  I cleaned the stud and the plastic chassis off really good with starting fluid to make sure there was no oil in there.  Next I mixed up a dab of JB Weld and put some in the hole and a touch on the stud and ran it tight then carefully removed the double nuts to ensure the stud didn't loosen up.

I put it all back together and went back to cutting.  Two days later I checked the bar nuts again and it seems to be holding for now.  I'm thinking that will take care of it, but I'm kinda wishing I had done the other stud too while I was at it.  From now on I will be even more careful tightening them.  I've looked for a reccomended torque spec so I could set it and then calibrate my thumb pressure...  I have big thumbs... 

Finding this thread let me know that I'm not alone and the diagram surprised me that these studs were in the plastic chassis.

[lil171]

My new MS 171 just had this the other day as well! Carefully removed the stud, side cover, bar and chain all together. Removed the stud from the assembly carefully then reinstalled it using a double nut. While still new to me, under a month old, I took it back to the shop I bought it at. They re-tightened it very tight they said, ran a die on the outside of the stud, replaced the nut and reassembled it for me. However, what worried me is they overtightened it when assembling it in front of me, but when it was getting fixed, I asked the repair person how tight it should be. He let me undo it and I was shocked at how tight he had it using an extended length scrench. I retightened it to what I thought was tight then he told me to give it more. At least it is fixed now!