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Mcculloch MAC 335 loses power and dies..

Discussion in 'Tools and Materials' started by clocKwize, 24 Jun 2017.

  1. clocKwize

    clocKwize

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    I emptied this out when I got it and refilled it with fresh stuff. It seems to be coming out more than ok (I just had a small puddle after starting it and letting it idle on the floor for a while :/) Not sure what you mean about the bar being adjusted properly - the chain is at what I feel is the correct tension after reading online, its not too loose, not too tight.
     
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  3. clocKwize

    clocKwize

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    So I had a tinker this morning, it started and idled for a while and started sounded a bit spluttery though, I increased the idle screw so it idled a bit quicker hoping this would help. It didn't - after idling for a while it slowed down and stopped. I did get the chain moving properly and it seemed ok for a little while.

    Do you think it'd be worth while to take out the carb and clean it? I've watched a video online - doesn't seem too fiddly/difficult, just need to be careful to put things back in the right order and be gentle with the gaskets (or just leave them be).

    I've cleaned the air filter out and replaced that - didn't make any difference but wasn't that dirty anyway. Going to order a fuel filter. If I do clean the carb, I'll run compressed air through the fuel line also in case there is anything blocking it.

    2 other things I've noticed
    - When the chain brake is off, the chain sometimes spins on its own without the trigger held (sounds dangerous!)
    - Today when I was tweaking the carb, afterwards there was a small puddle underneath the start of the bar/chain, was almost dripping out.. I've just put a large amount of blue roll under it hopefully its not leaking!
     
  4. lostinthelight

    lostinthelight

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    Thats why I thought the brake was on because the idle revs seemed high for it not to be moving, cut them back a little. if it continues to move with the revs lower the springs in the clutch may be weak or broken.
    There may be oil on the floor but not getting to the bar, hold the end of the bar a little way away from a piece of wood, you should observe a spray of oil over it if working correctly.Be careful not to touch the end of the bar against to wood to avoid a potentially dangerous kickback.
    litl
     
  5. Burnerman

    Burnerman

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    Use a 50:1 mix if you are using a top quality oil, such as Stihl's own, or Oregon or similar. Oil for the standard two stroke scooter really isn't good enough in many cases.
    If the chain continues to revolve then either the revs are too high or the centrifugal clutch is rusted up, and the springs aren't drawing the shoes back.
    Before you dive into the carb, try the L screw a quarter of a turn one way, and then start up. Then try a quarter of a turn the other way and try again.....it may get some sort of tickover.
    Start the machine on full throttle with the chain brake off.
    If you want to strip the carb thats fine, but you may need diaphragms and gaskets....again, GHS can help. Also check for splits in the fuel lines.....McCullough stuff isn't as good as Stihl etc.
    You can happily run the machine with the chain bar off - you'll also see how the oil gets from the pump, through a hole in the bar and then onto the chain.
    John :)
     
  6. clocKwize

    clocKwize

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    Great, thanks both. I'll have another go again soon once parts have arrived :)
     
  7. Stivino

    Stivino

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    I've got the handbook for that saw. If you want to know anything specific, just ask.
    Quote from fueling and lubrication page.
    "This engine is certified to operate on unleaded gasoline. Before operation, gasoline must be mixed with a good quality 2-cycle air-cooled engine oil. We recommend McCulloch brand oil mixed at a ratio of 40:1 (2.5%). If you don't use this oil, use a good quality 2-cycle air-cooled oil designed to be used at 33:1.
    HTH
     
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  8. Burnerman

    Burnerman

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    Your input is much valued, Stivino......you don't post much these days!
    John :)
     
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  10. Stivino

    Stivino

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    Thanks, I visit the forum most days for a read but I don't seem to have much to add.
    I have that particular saw, I've had it for 15 years and I still have the receipt and the manual.
     
  11. clocKwize

    clocKwize

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    thanks for all the info. I've replaced the carb, air filter, fuel filter and taken all the easy taken apart areas apart and cleaned with compressed air and carb cleaner. Didn't so much "replace the fuel filter" - when I fished the tube out, there was no filter on it and it had a split in it. I cut the split part down and put the new filter on but after about 20 mins of me trying to start it and tinkering with the carb adjustment screws, it had split again and the filter is in the bottom of the fuel tank. sigh.

    Does anyone know where to get the right diameter fuel lines from? I couldn't find them on GHS. Was still having trouble getting it to idle, I'm going to remix the fuel and replace the fuel line, hopefully that helps.

    So the oil I have is this: http://www.homebase.co.uk/en/homebaseuk/alm-2-stroke--oil---1l-363709 - is that pants, will it be make or break? I'll replace it if it gets the chainsaw running properly, but I suspect I've got bigger problems right now :D

    Cheers
     
  12. lostinthelight

    lostinthelight

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  13. clocKwize

    clocKwize

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  14. lostinthelight

    lostinthelight

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    Not sure, I have most sizes here and shove on the size that fits but you could use a drill bit that just slides inside the existing tube to get the size ? you could give GHS a call to make sure the od size will give a tight enough fit in the tank grommet

    litl
     
  15. clocKwize

    clocKwize

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    Good idea :) Its on order, should be here Friday. Starting to wish I'd just bought a new chainsaw lol. I am learning about 2 stroke engines and things though. All good fun.
     
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