1. Welcome Hearth.com Guests and Visitors - Please enjoy our forums!
    Hearth.com GOLD Sponsors who help bring the site content to you:
    Hearthstone Soapstone and Cast-Iron stoves( Wood, Gas or Pellet Stoves and Inserts)
    Caluwe - Passion for Fire and Water ( Pellet and Wood Hydronic and Space Heating)

MS 360 Repair (Help needed)

Post in 'The Gear' started by jensent, Jan 19, 2013.

  1. jensent

    jensent Member

    Joined:
    Apr 22, 2010
    Messages:
    156
    Loc:
    central Ill
    Have an MS 360 that scored the piston and cylinder on the exhaust port side. Have replacement parts. Could sure use any and all advice from those who have experience with this type of rebuild. I am assuming it went lean to damage the p&c in that area. What steps would you take to prevent this from happening again. Haven't found anything obvious. Are there lubs that should be used in the assembly. I don't want to fire it with the cylinder walls dry do I?
    Thanks
    Tom

    Helpful Sponsor Ads!





  2. Freeheat

    Freeheat Minister of Fire

    Joined:
    Feb 1, 2010
    Messages:
    565
    Loc:
    West of Cleveland
    I use 2cy oil on the walls for a pre-lube , make sure you clean and adjust the carb
  3. rkshed

    rkshed Feeling the Heat

    Joined:
    Jan 15, 2012
    Messages:
    262
    Loc:
    NH
    I always lightly lube the walls with premix when reassembling. The argument has been lubed causes glazing on start up and therefore takes longer to seat the ring/rings.
    I'll take the chance and after 30+ years, I haven't had a failure from it.
    ScotO likes this.
  4. jensent

    jensent Member

    Joined:
    Apr 22, 2010
    Messages:
    156
    Loc:
    central Ill
    Thanks, the more suggestions the better I feel. So Smokin' Jay and the rest jump in!
    Tom
  5. Angelo C

    Angelo C Member

    Joined:
    Apr 11, 2010
    Messages:
    82
    Loc:
    Peoples Republic of NJ
    What do you consider "the replacement parts" we can start from there. If its just the piston, rings and cyl then we need to chat some....about the case gasket set, bearings and hoses that all should be gone through too. All after we confirm what caused the lean burn in the first place.
  6. jensent

    jensent Member

    Joined:
    Apr 22, 2010
    Messages:
    156
    Loc:
    central Ill
    Ok Angelo if your willing I need guidance. Have piston, cylinder, ring, pin, c-clips and base gasket. What else do you think we should replace or test before assembly? Also how do we test our work as we progess and when we finish to see if there are air leaks. How do we find what caused the lean burn? Anyone who wants to jump in is sure welcome.
    I think it over-heated when my 250lb son leaned on it with a chain that would only throw dust in a 40in red oak until the saw quit.
    Tom
  7. Angelo C

    Angelo C Member

    Joined:
    Apr 11, 2010
    Messages:
    82
    Loc:
    Peoples Republic of NJ
    Start with pressure and vacuum testing everything that looks like a hose or has a hose attached to it before you break it down. Make sure the case hold pressure and the bearings are smooth and the bearing seals are...um sealing. Can you post a pic of the cyl ?
  8. MasterMech

    MasterMech Guest

    Block/seal the exhaust and intake ports. Make sure the decomp valve is closed and there is a spark plug in it. There are special tools to connect a vacuum/pressure pump to the engine, most of the time you can just hook onto the impulse line port. You want to apply a bit of pressure, then vacuum and make sure it holds. Soapy water will find any leaks that show up under pressure.

    Visually confirm the condition of the impulse line and intake boot. No cracks or punctures are permissable. In fact, both the impulse line and fuel line/filter should be replaced at this time without question. Confirm the carb is ok with a "pop-off" pressure test or just do a gasket/diaphram kit there too. No need to split the case unless something is wrong with the bearings or case gasket.

    This all can and should be done with the old piston & cylinder in place. Then repeat after the engine is reassembled.
    ScotO likes this.
  9. Angelo C

    Angelo C Member

    Joined:
    Apr 11, 2010
    Messages:
    82
    Loc:
    Peoples Republic of NJ
    We are talking about enough pressure/vac to fill a basketball not a truck tire...8-10 lbs max. Also rotate the flywheel a few times while it's under pressure, sometimes the seals elongate and don't reveal the leakage w/o a turn or two. A mity vac brake bleeding tool can usually be borrowed at autozone for free. They take a credit card for deposit and return your money when you return the tool. You can buy a decent compression tester there too. Make sure you get one with a release valve at the head.
    ScotO likes this.
  10. jensent

    jensent Member

    Joined:
    Apr 22, 2010
    Messages:
    156
    Loc:
    central Ill
    Saw is already apart. Suggestions?
  11. MasterMech

    MasterMech Guest

    May as well put the top end back together then (with new parts) and do your leak test once it's together. You don't have to split it or pull it apart again to change those seals should they need it. I would however, check the bearings for play (radial and axial) while it's apart.
  12. jensent

    jensent Member

    Joined:
    Apr 22, 2010
    Messages:
    156
    Loc:
    central Ill
    Guys, need answer to this question. New piston has an arrow on the top at an edge. Does this arrow note the intake (carb) side or the exhaust (muffler) side?
  13. Boog

    Boog Minister of Fire

    Joined:
    Oct 31, 2012
    Messages:
    592
    Loc:
    NE Ohio
    Exhaust side, that way the ends of the rings are on the wide solid side of the cylinder, otherwise the ends of the rings will catch on the ports if installed the other way.
    ScotO and MasterMech like this.
  14. StihlHead

    StihlHead Guest

    Arrow always goes forward toward the exhaust (direction of air flow).
  15. jensent

    jensent Member

    Joined:
    Apr 22, 2010
    Messages:
    156
    Loc:
    central Ill
    Thanks. I'll keep you posted as to the outcome.
    Tom
  16. jensent

    jensent Member

    Joined:
    Apr 22, 2010
    Messages:
    156
    Loc:
    central Ill
    Sorry I didnt follow with info on the rebuild. Finished rebuild without problems. Thanks to all who helped. Saw popped on 3rd pull, started on 4th. Ran it for about 30min, no load. Cut with it for about 15min at various engine speeds. Had dealer adjust carb and check top RPM. Now waiting for a truck load or two of wood from the local tree service.
    Thanks again!
    Tom
    ScotO likes this.
  17. Angelo C

    Angelo C Member

    Joined:
    Apr 11, 2010
    Messages:
    82
    Loc:
    Peoples Republic of NJ
    Did you find out what the cause of then lean fire was?
  18. jensent

    jensent Member

    Joined:
    Apr 22, 2010
    Messages:
    156
    Loc:
    central Ill
    When the dealer rebuilt the carb he said that the impulse side was full of very fine dust. We had been using that saw to buck several 40 ft sections of dry dead standing red oak. Fresh chains produced more dust than chips even when new. I have found others having the same P&C problems with the 360,361,362 in dry dead wood on the arborist site. Stihl does show two different air filters for that saw. One is fabric for normal operating conditions. The other is a fleece filter(non-woven) for dry and dusty conditions. We had used the fabric. Has anyone used the fleece filter and what was your impression?
    Tom
  19. MasterMech

    MasterMech Guest

    I run the fleece filter on my 034 and whenever it was time to clean it, the inside of the filter and the carb bore are clean as a whistle.
  20. rkshed

    rkshed Feeling the Heat

    Joined:
    Jan 15, 2012
    Messages:
    262
    Loc:
    NH
    Does Stihl recommend adjusting the carb when changing to a tighter filter?
    I ask this because unless the surface area of the tighter filter is greater than the original, in theory, it will run a bit lean. Less air means you need to richen it up.
    Maybe the new fleece filter is more or less just like putting mom's old nylons over your air filter. Then the air intake really wont be changed until it starts to get coated with dust.
    Just curious...
  21. smokinj

    smokinj Minister of Fire

    Joined:
    Aug 11, 2008
    Messages:
    15,972
    Loc:
    Anderson, Indiana
    You should adjust carb when needed....
    ScotO likes this.
  22. Bigg_Redd

    Bigg_Redd Minister of Fire

    Joined:
    Oct 19, 2008
    Messages:
    3,800
    Loc:
    Shelton, WA
    1) don't straight gas it

    2) make sure your carb is tuned somewhere in the factory specification ball park

    3) coat everything with 2 stroke oil during reassembly
  23. MasterMech

    MasterMech Guest

    I think you got that backwards..... ;)
    ScotO likes this.
  24. rkshed

    rkshed Feeling the Heat

    Joined:
    Jan 15, 2012
    Messages:
    262
    Loc:
    NH

    Yah, yah! Crap! Sorry about that!
    I just spaced that one.
    Still, don't you need to adjust the carb or is there no effect at all?
  25. MasterMech

    MasterMech Guest

    I would run the saw and see how it sounded. Maybe tweak it a bit if I felt froggy but if my ear says all is good, I don't worry. ;)
    ScotO likes this.

Share This Page