Buy Used Saws CCC Ebay Store

Stihl FS 46 String Trimmer Problem

Discussion in 'Mowers and More' started by Wood Doctor, Aug 10, 2017.

  1. Fish

    Fish Super OPE Member

    Joined:
    Jan 18, 2016
    Messages:
    437
    Likes Received:
    616
    Trophy Points:
    178
    Location:
    Manton Ky.
    I had a new block that the crankshaft was off @ 90 degrees, so I sent the customer another, plus some freebies for his trouble. I told him to keep the old block for parts. I was curious about the internals of the block, but not enough to pay the return shipping.
     
    DustGrind likes this.
  2. DustGrind

    DustGrind Active OPE Member

    Joined:
    Aug 9, 2017
    Messages:
    17
    Likes Received:
    19
    Trophy Points:
    33
    Location:
    Hayfields
    I'm sorry. Just read where someone was going to send you a new flywheel. Thought that was very generous of him, then read where you said it may not run.
    I'm just learning here. Sorry.
    Didn't mean to offend you.
     
  3. Wood Doctor

    Wood Doctor Edwin

    Joined:
    Feb 9, 2016
    Messages:
    616
    Likes Received:
    1,745
    Trophy Points:
    203
    Location:
    Omaha, Nebraska
    Well, there is no shipping involved here. My curiosity and time is the only price I have to pay. If it all fails, I'll keep the parts. Heck, I imagine a Stihl dealer already quoted him a $200 repair price or condemned it.
     
  4. Fish

    Fish Super OPE Member

    Joined:
    Jan 18, 2016
    Messages:
    437
    Likes Received:
    616
    Trophy Points:
    178
    Location:
    Manton Ky.
    well, popping on a brand new block for $30, he could hopefully handle.
     
  5. backhoelover

    backhoelover SERVICE MANUAL MASTER

    Joined:
    Feb 10, 2016
    Messages:
    779
    Likes Received:
    1,322
    Trophy Points:
    208
    Location:
    lincolnton nc
    i might have a good used flywheel can you send a pic? you can have it of course
     
    Lone Wolf and DustGrind like this.
  6. backhoelover

    backhoelover SERVICE MANUAL MASTER

    Joined:
    Feb 10, 2016
    Messages:
    779
    Likes Received:
    1,322
    Trophy Points:
    208
    Location:
    lincolnton nc
    that flywheel fits 45 different models anything mm fs hl km fc 55,38,45 will work
     
    DustGrind likes this.
  7. Wood Doctor

    Wood Doctor Edwin

    Joined:
    Feb 9, 2016
    Messages:
    616
    Likes Received:
    1,745
    Trophy Points:
    203
    Location:
    Omaha, Nebraska
    I suppose what worries me most is safely removing the flywheel after I pull the engine from the case. I've done this many times with chainsaws but never with a string trimmer engine. I'm assuming that there is a timing key for proper positioning that is likely sheared off.
     
  8. Fish

    Fish Super OPE Member

    Joined:
    Jan 18, 2016
    Messages:
    437
    Likes Received:
    616
    Trophy Points:
    178
    Location:
    Manton Ky.
    First thing will be the clutch drum.

    38 001.JPG
     
    Wood Doctor and DustGrind like this.
  9. Fish

    Fish Super OPE Member

    Joined:
    Jan 18, 2016
    Messages:
    437
    Likes Received:
    616
    Trophy Points:
    178
    Location:
    Manton Ky.
    Then the clutch, I just clamp it in a bench vice and turn the flywheel.

    38 002.JPG
     
    DustGrind likes this.
  10. Fish

    Fish Super OPE Member

    Joined:
    Jan 18, 2016
    Messages:
    437
    Likes Received:
    616
    Trophy Points:
    178
    Location:
    Manton Ky.
    Then I use a deepwell socket on the clutch, and whack it with a hammer to dislodge the flywheel.

    38 003.JPG
     
    Wood Doctor and DustGrind like this.
  11. AVB

    AVB Well-Known OPE Member

    Joined:
    May 4, 2016
    Messages:
    202
    Likes Received:
    192
    Trophy Points:
    58
    Location:
    Elora, TN
    For flywheel removal on of these and other 2 cycles I use one of these flywheel knockers. I had two of these made for the two different thread patterns that I commonly run into. So much better than banging on the clutches. Less chance of striking the crankshaft end with a hammer. With either method you back about one turn from seated to allow room for the flywheel to unseat.
    [​IMG]
     
    Wood Doctor and DustGrind like this.
  12. Wood Doctor

    Wood Doctor Edwin

    Joined:
    Feb 9, 2016
    Messages:
    616
    Likes Received:
    1,745
    Trophy Points:
    203
    Location:
    Omaha, Nebraska
    I note that Fish left on the carb after removing the fuel tank. Makes sense because the carb is secure and the fuel lines can be removed together with the tank.

    I have a 3-arm device that can pull the flywheel slowly. I'l try that first after removing the clutch drum and clutch. Those might be tougher than removing the flywheel.

    Looks like there is a timing key on the shaft. It will be interesting to see if that sheared in this engine or if another mechanic failed to tighten the nut and set up the flywheel slippage or never even thought about the timing issue. I'll be sure to post results. Give me some slack on this because I want to be careful and take a few good Pics.
     
    DustGrind likes this.
  13. Fish

    Fish Super OPE Member

    Joined:
    Jan 18, 2016
    Messages:
    437
    Likes Received:
    616
    Trophy Points:
    178
    Location:
    Manton Ky.
    I tear down @ 1 of these a week in the summer months..
    Takes 5-10 minutes. I just snapped pics of various blocks, the carb/tank still on thing was purely by chance, no plan involved.
    I just yank off the part needed to ship, I have a chitload of blocks/parts laying about.
     
    DustGrind and Dub11 like this.
  14. AVB

    AVB Well-Known OPE Member

    Joined:
    May 4, 2016
    Messages:
    202
    Likes Received:
    192
    Trophy Points:
    58
    Location:
    Elora, TN
    I believe once you try the flywheel knocker you'll find it works much better than a puller. Besides on many chainsaws you simply can not get a puller in there to even grip the flywheel. I use a 2# brass and the knocker and it only takes a few taps to jar the flywheel loose , usually one or two. Sure saves taking all the cover off.
     
    DustGrind and Wood Doctor like this.
  15. Fish

    Fish Super OPE Member

    Joined:
    Jan 18, 2016
    Messages:
    437
    Likes Received:
    616
    Trophy Points:
    178
    Location:
    Manton Ky.
    I have always been a BIG fan of knockers!!!
     
  16. Termitebuffet

    Termitebuffet Home of the corn can muffler .....

    Joined:
    Jan 2, 2016
    Messages:
    1,699
    Likes Received:
    7,914
    Trophy Points:
    330
    Location:
    Midgetville Norf Kacolacky
    Fixed
     
    angelo c, DustGrind and Jimmy in NC like this.
  17. Fish

    Fish Super OPE Member

    Joined:
    Jan 18, 2016
    Messages:
    437
    Likes Received:
    616
    Trophy Points:
    178
    Location:
    Manton Ky.
    Just took a little playing with......
     
    DustGrind likes this.
  18. Wood Doctor

    Wood Doctor Edwin

    Joined:
    Feb 9, 2016
    Messages:
    616
    Likes Received:
    1,745
    Trophy Points:
    203
    Location:
    Omaha, Nebraska
    OK, guys, here's the latest on the FS 46. I decided to remove the carb while working. I pulled the engine and removed the flywheel. Yes, the index timing key was sheared off. I used what was left on the flywheel keyway to align the flywheel. I was careful not to let the engine move while I tightened it back up.

    I tightened the clutch a bundle, making sure that the engine, flywheel, and drive shaft did not shift. Note that with the ignition module mounted to the engine, this is a must. On chain saws, the IM is secure to the case along with the engine and a flywheel nut moves to tighten it. That luxury is not available here.

    Engine started and ran, a little shaky at first, but then it smoothed out. It still has some shaking at low speed, so I may be off the ideal timing angle a few degrees. Top end power and speed is excellent, and it accelerates up rather nicely. This line trimmer has now been saved from the landfill. The owner will probably be in shock that the engine runs again.

    Oh, and BTW, the hardest part of the job was reassembling the plastic top with all the controls (wires, throttle, trigger, springs, etc.). Awkward as all get out, I figure that doubled my work time.
     
    Last edited: Aug 15, 2017
    Dub11, DustGrind and Lone Wolf like this.
  19. Fish

    Fish Super OPE Member

    Joined:
    Jan 18, 2016
    Messages:
    437
    Likes Received:
    616
    Trophy Points:
    178
    Location:
    Manton Ky.
    That is why I sell the bottom half and all of the innards as one part [except for the throttle cable] 38.jpg ....
     
    DustGrind and Wood Doctor like this.
  20. Wood Doctor

    Wood Doctor Edwin

    Joined:
    Feb 9, 2016
    Messages:
    616
    Likes Received:
    1,745
    Trophy Points:
    203
    Location:
    Omaha, Nebraska
    That release that allows the bottom trigger to work (and the fast idle catch) is a real gem. It pops up loose too easily and its own spring will knock it right out. The other real monster turned out to be the trigger itself and yet another spring that enjoys coming loose. If either of those two small springs fails or is not installed right, the whole mechanism will not operate properly.

    Then the two switch wires on the trimmer I worked on were supposed to travel along the top right edge where barely enough clearance was available. And, all of this had to be done with the engine and long pole in place. I used a small C-clamp to help out, but that seemed a bit make shift.

    After it was all over, I was thankful for a night time Aleve tablet.
     
    Last edited: Aug 15, 2017
    DustGrind and angelo c like this.
Loading...

Share This Page

Loading...