Help Troubleshoot Old McCulloch

[Witterings]

I've an old McCulloch Mac 335 that sat for 20 years when we didn't have a fireplace without being used and old fuel left in it.

 

I sent it off for a service a while back, I'm guessing they probably cleaned the spark / air filter and it starts fine and runs perfectly for the 1st 4 / 5 cuts but then as it starts warming up it starts cutting out under any load.

It's got new Aspen in it so I'm guessing it's probably the tuning, from what I've described does it sound like the high may need opening up a little??

 

It may well be the saw / carb's shot, you can get a copy carb for £20 .... not sure if it's worth spending the money or not, I've never taken a saw apart but there are youtube vids on how to but if it's anything more than just that I wouldn't know how to diagnose it so would have just wasted the money for a new carb.

 

Any thoughts / help appreciated. 

Edited March 8, 2021 by Witterings

[Khriss]

Electronic or points ignition? ( could be the points capacitor)  k

[Witterings]

26 minutes ago, Khriss said:

Electronic or points ignition? ( could be the points capacitor)  k

 

Showing myu complete lack of knowledge here I don't know and wouldn't know how to tell I'm afraid 😶

[Khriss]

43 minutes ago, Witterings said:

 

Showing myu complete lack of knowledge here I don't know and wouldn't know how to tell I'm afraid 😶

Probably will say on case, pic would help but definately worth sorting a vintage saw out  🙂  they usually have little bore piston wear, gummed up using shit oil usually, so recoverable, carb swop and new fuel pipes worth a shot. k

Edited March 8, 2021 by Khriss

[Stubby]

1 hour ago, Witterings said:

I've an old McCulloch Mac 335 that sat for 20 years when we didn't have a fireplace without being used and old fuel left in it.

 

I sent it off for a service a while back, I'm guessing they probably cleaned the spark / air filter and it starts fine and runs perfectly for the 1st 4 / 5 cuts but then as it starts warming up it starts cutting out under any load.

It's got new Aspen in it so I'm guessing it's probably the tuning, from what I've described does it sound like the high may need opening up a little??

 

It may well be the saw / carb's shot, you can get a copy carb for £20 .... not sure if it's worth spending the money or not, I've never taken a saw apart but there are youtube vids on how to but if it's anything more than just that I wouldn't know how to diagnose it so would have just wasted the money for a new carb.

 

Any thoughts / help appreciated. 

Could be low compression . Starts fine but when it heats up clearences open up to the point were it wont support combustion .  Also could be blocked tank vent . Runs for a bit then pulls a vaccum in the tank . you can test for this by cracking open the tank cap as its about to die and see if it picks up .

[Witterings]

All of the above makes sense but I'm wondering if I may be best taking it in somewhere as I could just end up spending money on it and not resolving the issue. 

At least someone who knows what they're doing should hopefully be able to diagnose the problem 1st and then decide if it's worth repairing or not.

 

Cheers for the help much appreciated even if it did just highlight how little I actually know about them 😃

[Khriss]

Worth cleaning n dismantling yrself. Not going to cost massive money on parts which are plentiful. If knackered you got to see how it fits together, take lots of pics as you dismantle. Think myself its carb or pipes, but have a go!  K

[Witterings]

13 minutes ago, Khriss said:

Worth cleaning n dismantling yrself. Not going to cost massive money on parts which are plentiful. If knackered you got to see how it fits together, take lots of pics as you dismantle. Think myself its carb or pipes, but have a go!  K

 

You know what maybe I should ... at least I'd learn and will probably thoroughly enjoy ... I may just try and mess around with the mix / tuning it before I do in case it's something as simple as that.

 

1 hour ago, Stubby said:

Could be low compression . Starts fine but when it heats up clearences open up to the point were it wont support combustion .  Also could be blocked tank vent . Runs for a bit then pulls a vaccum in the tank . you can test for this by cracking open the tank cap as its about to die and see if it picks up .

 

If it's hardly ever been used is it likely to be the clearances do you think .... I bought this when another saw got stolen and we moved shortly after buying it so it's had virtually no use at all but obviously leaving fuel in it for 20+ years is a killer as I now know.

[Stubby]

3 minutes ago, Witterings said:

 

You know what maybe I should ... at least I'd learn and will probably thoroughly enjoy ... I may just try and mess around with the mix / tuning it before I do in case it's something as simple as that.

 

 

If it's hardly ever been used is it likely to be the clearances do you think .... I bought this when another saw got stolen and we moved shortly after buying it so it's had virtually no use at all but obviously leaving fuel in it for 20+ years is a killer as I now know.

Ok . Try the tank vent then .  You never know . 🙂 Nothing to loose .

Edited March 8, 2021 by Stubby

[Witterings]

21 minutes ago, Stubby said:

Ok . Try the tank vent then .  You never know . 🙂 Nothing to loose .

 

Are all tank vents like the one in this video at 2 minutes to save going through the whole thing

 

 

 

Or are some built into the fuel cap .... not sure if it's relevant but the little bit of plastic that attaches to the lid and goes into the fuel tank to stop it rolling away when you take it off, there's a little twirly bit (I'm sure that's the  technically correct name for it 😄 ) that inserts into the lid and it's come away ... not sure if that could have anything to do with it but thinks it's probably unlikely?