MS 151 T C-E new machine, easy start not working

[NHden]

I bit the bullet last week and brought home a new MS151TC-E. It is a sweet little saw and I retract half of my comments of last week or so. You will need to be more gentle than with a pro saw and metal construction. Stihl considers the plastic screws a permanent thread IF you torqued properly (and find the thread start) so I'll do that.

The dealer said it was not easy start, and I felt nothing that indicated easy start in the pull(s). Checking their paperwork days later, they admitted it was a -E which should be easy start. I finally took off the starter cover today and the easy start parts are indeed present and in perfect condition.

With one slow gentle pull, there is never a trigger point where the 2nd spring energy is transferred to the crank. I read a comment elsewhere that one pull past the first compression point to set it up, then another gentle pull worked for them on another model. But nada.

At no time do I ever feel or hear a release of the second spring. All parts involved in holding the spring, grabbing both tails, etc. look perfect, as does the spring shape.

Any thoughts on what the problem might be? You guys are great. This model has very little exposure online or in person at dealers around here.

I should probably mention that the dealer, who is pretty good technically, did say there are 2 easy start systems and the 151 has a higher pull spring than some other saws. Not sure why since it's a smaller displacement engine.

 

[NHden]

I'm gonna throw out a theory. I wasn't sure how this system worked until after I posted this. When you pull the rope and this spring is compressed, after the next compression peak, the spring revs the crank fast for a brief period. It's that simple.

My theory:

1. the dealer mentioned that this spring is harder than on larger models
2. the dealer did perform fast, hard pulls on the first starting when I bought it, which the 151T manual TELLS you to do, but not what you're supposed to do with easystart (per other documents, videos)

While I can feel the second spring, tomorrow I'm going to remove it and check under a microscope. My theory is that it may have developed a crack.

 

[ZeroJunk]

I don't really know a good terminology for it, I just refer to it as double clutching.
Pull the rope until you feel the tension build up, then let the handle all the way back in and it should spin the crank in the first half pull or so of the next pull. You can do it over and over that way, takes like half a second.
Works reliably that way and you won't be taking the saw back in to get the spring replaced.

 

[RedneckChainsawRepair]

I've seen 2 different easy start types in from stihl on the bench.

1 is just spring assist.

2nd one winds up pulling with 2 fingers on short pulls if you like. Once wound up with short pulls spins over to start.

Sounds like you have #1. Take it easy on that easy start crap. Dont pull like a he man would on regular saws.

 

[NHden]

I think both of you hit the nail on the head. A few minutes ago, I pulled a number of times, observing what the spring does when you pass the compression peak. It does nothing you can see but would be throwing a bit of extra torque into your pull.

The system ZeroJunk describes sounds like it will start the engine. And the spring is much larger than the 151T from photos I've seen.

This is definitely number 1, just an assist, described by RedneckChainsawRepair.

Thanks guys. Mystery solved. I see very little benefit to this so if the spring ever breaks, I'll machine a solid replacement that looks like it but without the turns.

 

[ZeroJunk]

I see very little benefit to this so if the spring ever breaks, I'll machine a solid replacement that looks like it but without the turns.

Now, there's an idea I had not heard.
I believe these were intended for people who had trouble pull starting a saw.
Usually when they come in broke the man says my son, or grand son borrowed it.

 

[NHden]

There's tremendous force on the two square wire ends of the spring but even worse on the nylon landing zone (a hole in the gear like part and an S bend in the lower white plastic part.

 

[RedneckChainsawRepair]

There's tremendous force on the two square wire ends of the spring but even worse on the nylon landing zone (a hole in the gear like part and an S bend in the lower white plastic part.

Yep replacing that crap all the time.

I try to explain folks to not rip on these spring assist ones. Husky uses it, echo, poulan too. Same dang design and weak points like you noticed.

 

[RedneckChainsawRepair]

Just thought of something you might try when time arises. See if there is a 151 regular cover. Might work on your saw and bypass the middle part altogether.
I dont see one though anywhere.

Some saw models this works on.

I know 490 spring assist I can put regular 4910 501 recoil on.

I did a spring assist swap on a 180 for a guy. Nothing else just standard cover.

 

[NHden]

If you'd like to experiment with a potential simple fix, think about this. A piece of quality double sided foam material, like 3m VHB. You'd cut a shape the size of the black part with center hole to just fit over the black part's center "hub". Thickness of the material should be greater than the gap between the black and white parts when mated. You would peel the self adhesive foam and stick it between the parts, compressed by the screw.

I think there's enough surface area on the black part so that a grown man would not be able to damage the foam, especially since it's compressed.

Let me know what you think or if you try it. I've gotta check the 151T and see if it lends itself to this simple repair.

Others on Youtube have melted the top and bottom parts together with soldering iron, like plastic welding.

There are various types and grades of self adhesive foams. Some are dense but when compressed, would hold the shape with less pressure on the mating parts. The more I think of this, it sounds quite good. The only thing I don't know is the surface area you have available on these parts.

Could you post a picture with better contrast to see the white part detail, and also show the diameter of the black part.

A part to fix this could potentially be made cheap by anyone with a laser cutter.

 

[NHden]

Just looked at a handful of easy start type mechanisms on Google. On many, the two facing parts have deeper, cylindrical shapes.

It looks as if you could fill the gap between the parts with an oil/gas tolerant RTV (not really necessary) and temporarily put them on a rod of non stick material (delrin, polyethylene, etc.) and squeeze together until cured. Then pull out the rod. The rod may not even be necessary if you can just assemble the two parts in place with enough RTV to fill the voids between them. Neatly wipe off the excess with a finger tip as you rotate the part.

I don't know what fixes are out there but these are my contributions for the evening.

 

[stihltech]

Just use it for awhile and get used to it. Sounds like normal operation. Many out that work just fine.

 

[tJKrider]

I did a spring assist swap on a 180 for a guy. Nothing else just standard cover.

I was going to do this on the 211 I used to have but found it took way more than just the cover, unfortunately!

 

[RedneckChainsawRepair]

I was going to do this on the 211 I used to have but found it took way more than just the cover, unfortunately!

250 is that way but uses the wind up easy start. Short pulls wind up easy start. I was amazed how that worked. Like a wind up toy till wound then zing to start.

 

[NHden]

It looks like various Stihl products had standard and easy start rotor pulleys.

As far as I can find, the 151 and 150 are the only models with the "inverted" drive, where the pawls are on the flywheel. edit - I see the MS230 also has the pawls on the flywheel.

This looks like another weak point. The pawls have springs which feel like they belong in a clock, not a chainsaw.

It almost looks like a good repair product area but if you made something to sit between the rotor pulley and the "carrier" which Stihl calls the 151 drive (looks like a large bevel gear that engages the pawls), your product liability would probably be through the roof.

I'll just enjoy the saw as is for now.