Stihl MS150 Starter Assembly Issue

[stheis004]

Hi, I noticed the pull cord starting to fray the other day so decided to be proactive and fix it before it broke. I hadn't done this for awhile and was just pulling screws and had the recoil spring blow up on me before I realized I had gone too far. Anyways, I got it all back together gave it a few pulls and then it was pulling but nothing was catching. I took everything apart and found this spring was bent. Hmmm, ok, well I ordered a new one put it in today and had a few pulls that felt good then the same thing happened where nothing was catching...pulled it apart and the new spring is bent just like the last one...Any ideas where I may be messed up? Here's a few side notes that may or may not help solve this...


- I have been having an issue with the on/off switch for some time and decided to look into that while I had it in the shop. I found a little tab for a ground (I'm assuming) has a screw holding it but what the screw goes into is stripped. Anyways, I took the flywheel off to get this sorted out / have access to the hole I was looking at...

- I had to rewind the recoil spring and have never done that, at first the middle wasn't catching on the starter rope housing so I bent it a little bit so it catches on there...

 

[jackjcc]

Have you checked the IPL to make sure it’s together right? Usually there is a washer in there, but I haven’t taken these apart yet. Something isn’t in the right place to bend two springs.


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[TheTone]

Exactly the same thing happened to me with a 193 (192?) TC. When I got the saw, the pull cord was dangling. When I disassembled the starter, the spring was bent. The spring is there to cushion the pull, but when the rope is shorter than the pull, it's easy to bend the spring, just as I did with the new one I put in after two pulls. What I ended up doing was to bend the spring back as close to the original shape as possible and spot weld the coils together to make the TC into a T. Works fine now.

 

[Sam R]

How does the carrier look that sits on top of the rope/rewind housing? If the teeth on that are worn you will have issues. Some how or other it looks like the transfer of the pull cord to the flywheel is not dead on, I'd suspect the carrier and pawls first.
For tensioning the spring the best thing is to seat all the spring & cord housing pieces, make sure it is seated correctly then take the cord all the way out (should be totally slack) and turn the housing clockwise until the cord has wound around it enough to make the pull handle seat in the rope guide, THEN manually unwind the rope without letting off the tension of the spring and pull it all the way out the rope guide. Then slowly let it rewind itself into the housing - if done correctly it should rewind into the guide bushing and seat firmly. If it's wicked tight, do the reverse of the above, if it's so loose the handle hangs, add an additional turn.

 

[stheis004]

Hey thanks for the replies guys, so somethings still up...I found an entire starter assembly on eBay and thought that would be easy enough to just replace the entire thing and eliminate anything i might have messed up. While, I put it on today and gave it about 4 or 5 pulls and the plastic sprocket in it broken into 3 pieces...any ideas? I think it’s gotta be something with the saw at this point...

 

[Sam R]

You're not yanking on it real hard like any non easy start machine are you? With those you basically just ease it out and once the tension of the secondary spring reaches a certain threshold it'll release and spin the flywheel. Doesn't take a yanking motion though.

 

[stheis004]

You're not yanking on it real hard like any non easy start machine are you? With those you basically just ease it out and once the tension of the secondary spring reaches a certain threshold it'll release and spin the flywheel. Doesn't take a yanking motion though.

Good thought but I’ve had this for over a year and it’s one of my most used saws, Ive got a pretty good feel for what it takes...

Could the off and on of the flywheel done anything? That’s really all I actually did...

 

[Sam R]

Maybe so. Some how or other that secondary spring was way over torqued by something. I'd examine the assembly carefully to see where it's either not seated right or is getting bent by something. Might be the flywheel but that could only be if something wasn't on properly.

 

[stheis004]

I had time to take a look at it this weekend, the keyway on the flywheel is sheared off...so does it make sense if it was not set just right it could have caused some extra resistance when trying to start it that would have caused it to break stuff in the starter assembly? I’m waiting on the new piece for the starter now but hopefully I can set the flywheel in the right spot without the key if I’m just very careful?

 

[Sam R]

I wouldn't try and use it without a key. If it wasn't seated right or had some rotational play then I'd suggest that would be at least part of your problem. Since you've got it apart I'd inspect the pawls on the flywheel very carefully. Make sure their action is solid and that their springs aren't bent up or otherwise causing them to interfere with the carrier w/ the secondary spring on the rewind mechanism. I'd go even further than that and try and figure out why the key sheared in the first place, too.

 

[stheis004]

Good points Sam, and again thanks for the help. Pawls look good. Now as to why the key sheared, I'd like to blame that on user error, either while taking it off or putting it back on and somehow messing it up. This all started from a starter cord starting to wear with the saw running fine...