MrChooks

Texas - if you have an impact wrench - that would be perfect. They can be adjusted and give a multitude of smallish shocks to loosen the thread fit - and that is way better than big lumps of brute force.

At a 19mm thread - I would set the wrench up to the same (undoing) torque as you would use for a large car / small truck wheel stud and see how you go. If that isn't enough - just gradually increase the torque / impact.

Also before you start - squirt a bit of light oil / spray lube (WD 40 etc) into the thread. It works better if you do that a good few hours beforehand, so it has time to work its way along the threads.

Sorry - looks like a quick trip out to your cold shed tonight to give it a squirt

Texas rose

Just been and done just that! we'll see what tomorrow brings

MrChooks

Texas - well done - you've read my mind - now you can have a little sit in front of your fire and get warm

SABL

Impact wrenches are great.... I have them, too. Use them to get the blades off of the mower.

Best of luck Tr...you are in good hands with MrChooks!!

Texas rose

Haven't been out yet just finished breakfast.

I was wondering if the owner of the saw has been running it on neat gas?

Because of a heart problem/operation he had 2 years ago, he has asked me to keep an eye on his property in his absence - which he has been refurbishing for the last 10 years...It's his Mothers old house, but he actually lives 4 hours drive away.

He last used the saw to cut through 20 5"x3" softwood floor beams about 4 years ago I seem to recall.

Now I have searched his home and outbuildings but cannot find any 2 stroke oil or mixing bottles...so what mix, if any, did he use?

He did have some gas in his shed, which he used in his lawn mower, but no 2 stroke oil.

Once I have repaired the saw I will ask him for more details....don't want to give him any more shocks...don't know if his heart will stand it

Using the saw without oil is well within his capabilities

SABL

Good detective work..... the damage might have been done, or at least well underway by the time you got the saw.

MrChooks

: Texas - that'll do it to 2 strokes every time!!! They will start and run for a while; but as soon as the engine gets hot, it will inevitably seize up.

And like SABL said - good detective work - 'cause everyone I know with 2 strokes, has a can of 2 stroke fuel and / or one of those infernal plastic mixing measures / pourers and a little bottle of 2 stroke oil laying about somewhere.

Texas rose

Thanks Mr Chooks and Sabl, this guy owns a builders merchants so he is not short of cash, probably couldn't be bothered to get some 2 stroke oil, wanted to get on, and just used what he had available. Did I mention there wasn't a trace of chain lube oil in it either?

The more I think about it, and knowing him, I think the neat gas could well have been the problem.

The plastic? cages which were supposed to keep the ball bearings equally spaced out in the tracks, have shattered into a million bits, jiggering the oil seals in the process.

I have ordered new bearings and seals and they should be here in a couple of days, unless the Xmas post dictates otherwise.

Incidentaly, the chain brake/clutch assembly was - as you suggested - Left Hand thread and came off no bother with the air wrench.

The only suspect parts are the piston skirt, it is scrubbed away down 1 side under the rings by about 2+mm, but I intend to clean and re-use it. Both piston rings are free and undamaged, so I think I'll get away with it.

As soon as I get it put back together and it seems to be running OK, and after I cut my logs, I'll put it back in his property.

I wonder what I'll have trouble with next?

Tr.

MrChooks

A hearty well done to you Texas - (don't it feel good when things go right for a change!! and aren't air/impact wrenches just wonderful bits of gear!!:)

Yes, the cages separate the balls in the bearing, so when they collapse, all the balls "gang up together" and the bearing seizes / jams. That, and the heat generated by running without without oil, would explain the shot oil seals on the shaft and on 2 strokes, these are critical. They are critical because rather than keep the oil in, they ensure that excessive air isn't drawn in along the shaft which would wreck the air / fuel mix in the 2 stroke engine.

With new bearings and seals, you will have solved the crankcase issues just fine.

On the piston skirt / rings, if it were your chain saw, I would suggest they be replaced also, BUT as it belongs to someone else and all you need to do is get it going OK, you should be OK with the old piston / rings - air cooled 2 strokes are pretty tolerant of less than perfect fits in the bore. Power might be off a little, but otherwise you should be OK - and after all, all you want to do is cut up some firewood and be rid of this thing!!

Basementgeek

Please remember that this an older person, like me. Two cycles oil are fairly new ( ok 40 years probably).

I still own a 1964-65 McCulloch, MAC 15, chain saw( 80.3 CI) since 2 cycle oil was new then we could also use 30-40 motor oil. My old Mac owners manual calls for 8 oz of 40 weight oil to one gallon of gas, i.e. 16:1.
If did not have 40 wt I would use 30 wt.

Blue smoke (exhaust) is good, in my opinion. I mix everything close to 30:1.
As it has been said, plugs are cheap.

He may have just dumped some motor oil in the gas.

BG

Texas rose

Yes, I wouldn't think twice about renewing the piston and cylinder if it were my own saw. Once I get it going I think I'll forgo cutting my logs, instead I'll shove it back in his house and cut the logs by bow saw.

Wouldn't want to tempt providence now would we?

MrChooks

Absolutely agree with BG - I don't give a "rat's butt" for what the OEM makers say when they recommend these 50+:1 fuel / oil ratio mixes - I still use the tried and tested formula my "old Dad" taught me - 32:1 and let the blue smoke blow!!!

The only concession I make, is that at the end of working the 2 stroke, I shut off the fuel and run the carb bowl dry before putting the 2 stroke to bed.

It sure works for me, I have an old McCullough 18" chain saw (that I am reliably told, was the original chain saw used by Noah to build the arc!!) and a newish (5 year old) 2 stroke hedge trimmer - and both have never missed a beat with that fuel formula and shut down procedure.

The only issue I would confess with the rich oil mix is that if I leave the engine idling for a long time (like 1/2 hour) it will tend to oil its plug a bit; but under working load - there is never a problem.

SABL

Do they really have trees down under?? I think MrChooks uses the chainsaw for Roo hunting....... and the trimmer to shape up their tails.

MrChooks

Yes SABL - we have trees down here - great big hard wood mothers at that - but I have found the McCullough an absolute whizz at convincing my recalcitrant lemon tree to behave - all I do is put the chain saw down beside it for a little while, don't even need to start it up!! - and it fruits its little head off!!!!!

SABL

Off Topic.... but......

Is it there that they found them gigantic hardwoods buried in the ground?? And worth a fortune??

Lemon trees..lucky you. It's hard enough to get a peach tree to grow here.

Texas rose

I have been having a battle with my conscience all day, and I have decided to renew the piston after all. But I'm going to clean the cylinder bore - it's definately re-usable - so there!

Another thing that bothers me slightly, is that the new bearings will have metal cages and not the plastic? ones that were fitted originally.

What do you think, will the metal ones be OK on the gas/oil mix, or will they get hotter, quicker, than the plastic ones or am I just being paranoid?

Another slight niggle, you know the plastic boss (a brownish colour) that locates on the crankshaft between the crank oil seal and behind the chain brake device, which drives the chain oil pump worm? Is this held in place by the tightness of the chain brake assembly and not by it's own device?

Tr

MrChooks

Texas - "you old softie!!" - a new piston!!

Yes, - the cages aren't the real wear surface in a ball race - it is the inner race, the balls themselves and the outer race that are the ware surfaces. The cages merely keep the balls from ganging up together. My guess is they only use the nylon / plastic cages 'cause they are cheaper for the OEM.

If you are going to replace the piston, then you will very likely need new rings as well - Hopefully, you can reuse the gudgeons and big ends on the con rod.

Texas - given the circumstances (engine seems to have been run without oil by the owner), if it were me, I think would be very tempted to reassemble and see how the thing runs with the original piston 1st - but I guess I am a tightwad!!

Texas rose

Hello 'tightwad', not as tight as me...I haven't actually bought the new piston yet - it comes complete with new rings gudgeon pin etc, - but I have contacted the supplier with the relevant sizes/part numbers of the old piston and am awaiting his comments. The whole thing complete including P&P is £25, so for that I can buy peace of mind.

Bye for now,

Texas rose

UPDATE :

The saw is up and running, cut the tree and sawn it up for logs...didn't want to have to borrow it again after the owner got it back 'case he knacked it up again.

Still haven't told him of the repairs.

Thank you all for your help and patience.

Texas rose

MrChooks

A hearty well done to you Texas

I suggest you cut enough wood to last a while - that way you will be OK for a good while

Being serious for just a moment - how about leaving a couple of gallons of proper 2 stroke fuel with the saw when you return it - at least that way its "mechanically challenged owner" may put it on its correct diet - so when you need to borrow it again - you wont have to do a complete overhaul 1st

Well done again and we were all pleased to help where we could