McCullough chain saw problem

Discussion in 'Mechanic and Repair' started by Roger, Jan 28, 2006.

  1. Roger

    Roger LawnSite Fanatic
    Messages: 5,943

    I do some work that requires a chain saw. Somebody gave me a McCullough Mighty-Mac (I think that is the model, at least XXX-Mac), 16" bar, several years ago. I knew it wasn't much of a saw, but I have used it many times, and has served me pretty well for my limited needs.

    Yesterday, I cut down some badly overgrown yew bushes and hauled away the debris (bonus work for this time of the year!). In the morning, it ran pretty well, started with a little difficulty. But, in the afternoon, it would start OK when cold, but I had great difficulty getting it started when warm (e.g. after refueling, or after loading debris for hauling). I used it for a job last Fall, and had similar problems.

    Taking out the spark plug, cleaning with wire brush, and reinstalling, usually helps enough to get it started, albeit difficult. I installed a new plug last Fall near the end of the project, saw improvement, and I felt the problem had been solved. Now, I believe the problem is beyond the plug.

    I have not tinkered mechanically with chain saws. I have inspected and cleaned the air filter. I have insured the choke works properly. Also, I checked exhaust ports and found them clear.

    The one thing I'm questioning is the primer bulb functioning properly. However, I know that it must be working when the engine is cold. For other engines, use of the primer for warm start is not necessary. But, I have tried it on this chain saw as a secondary tactic, not as a matter of course.

    The other item causing the problem might be a coil. Like I said earlier, I've not tinkered much with this machine, so I don't know "what's under the hood." I don't even know where to find the coil on this engine.

    Any suggestions on a good place to start troubleshooting?

    Don't suggest buying a new chain saw. I'm too close to being tempted, but my use is so limited I have a hard time spending $300 or so for a good Stihl saw.
  2. Lawn Masters

    Lawn Masters LawnSite Senior Member
    Messages: 850

    One problem, is you're using a saw that if its what I'm thinking it is, is around 20 years old, and you need to buy something much newer like a modern Stihl or something like that.

    the Macs of the mini mac, which is probably what you've got, are VERY complex saws. there is no mighty mac that I know of, unless its a later model made of all plastic. the mini mac is a little tophandle saw, capable of pulling 18" bars, at least the ones I've used could.

    The mini macs, if they develop problems, just toss em, dont bother to fix it cause you'll get so frustrated trying to pull the motor out of the case to even reach the carb to fix anything in em.

    The best course of action, would be pitch that thing, get yourself a Stihl MS250, or something similar like a husqvarna 300 series saw.
  3. Roger

    Roger LawnSite Fanatic
    Messages: 5,943

    I checked the saw today and it is a Mac Cat, 38 cc.

    Apparently, from the lack of response most feel like LawnMasters - scrap the piece. Anybody else with an idea.
  4. True Cut Lawn Maintenance

    True Cut Lawn Maintenance LawnSite Senior Member
    Messages: 418

    clean the carb.
  5. Signature Landscaping1

    Signature Landscaping1 LawnSite Bronze Member
    from Mass
    Messages: 1,496

    at least its not as bad as mine, my grandfather gave me a brand new muchulloch, prob from the late 80's early 90's, and it takes leaded fuel.
  6. Lawn Masters

    Lawn Masters LawnSite Senior Member
    Messages: 850

    38CC mac cat? those are worse yet. I'd DEFINATELY chuck it and find a higher quality saw. last one of those things I worked on, the carb is so sensitive to any adjustments at all that you'd swear you were fine tuning something that cant be tuned.

    btw, there never has been ANY chainsaw from McCulloch that required leaded fuel to my knowledge. Signature, post your model of saw, odds are the label was misprinted.
  7. Smalltimer1

    Smalltimer1 LawnSite Bronze Member
    Messages: 1,223

    I've never seen a McCulloch make it past a year old without being junked.

    If you can't afford a Stihl or Husqvarna, a Poulan Pro is a good economical but durable saw. We've used them in the tree business for 10 years and never lost one yet, using them on trimming, delimbing, and debris removal, and leaving the Stihls to do the heavy cutting like standing oaks, etc.
  8. cuttinggrassiscool

    cuttinggrassiscool LawnSite Member
    Messages: 71

    i wouldn just chuck, it but i dont know anything at all about that specific saw. i think one of the probles with are society is that it is throw away. things to check would be the coil like you said, cleaning the car(diapraghm may be bad?) or even the head gasket may be bad. if you really are at a loss of how to fix it ou may have a local repair shop with many years experiance and perhaps some left over old parts who i bet would gove you some advice. and if you think buying a new saw is the only way then i would recomend at least trying to fix this one, worst case you cant get it back tpgether and running but at least you learned something about how it works for te future.
  9. Smalltimer1

    Smalltimer1 LawnSite Bronze Member
    Messages: 1,223

    If you've ever used a Mc Culloch you'd know why we told him to throw it away.....:eek:
  10. Lawn Masters

    Lawn Masters LawnSite Senior Member
    Messages: 850

    Theres only ONE type of Mac I'd ever use, the OLD ones, solid magnesium throughout the machine, 99.9% of it is made of that stuff, and they're HEAVY. those ones, you just cant kill, the newer ones made of plastic, forget it they're as good as a walmart special poulan. Its one of those saws you just dont fix, cause once you fix the first problem, 3-10 more pop up. at least the older all magnesium ones were reliable as gravity although heavy as lead.

    This is personal experience I'm speakin from too, I've got 2 of those old magnesium Macs, a 10-10Auto, and an old 250, both run great, just cant kill either one of em, and I've been tryin for awhile. they've got what feels like a 10k hour lifespan on them before you have to re-ring em, and then you're good to go for another 10k.

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