Lawnmower engine clutch broken

[freepo]

Tecumseh vantage 50 - broken pawls Al-Ko BM 875 II Bought this brand new, but on Ebay from a guy in Italy, less than half the price including delivery. Unwanted or surplus stock or maybe he worked in the factory and he has access to the factory rejects...... who knows, I certainly don't.

It took a while to start at first, but once running it was ok, and after running a few times it became easier to start. Then the problems came....... often during starting the pull cord would come to a complete and abrupt stop causing me pain. After only a few hours running & starting it stopped starting, removing the starter cover, both pawls broken out and lost. Amazed to see they were only located in a plastic pulley wheel with thin plastic walls 2mm thick - the plastic walls had broken on both pawl housings. Found new starter assembly online but reluctant to buy and fit as surely same problem will happen again? What to do? Why does engine yank on the starter cord like this?

I just had a thought maybe the sudden yank on the cord was the starter spinning without the pawls going oput then all of a sudden the pawls sprang out to engage - that would do it, but I don't know if that is mechanically possible, I mean I can't remember how the pawls opened outwards whether by cetrifugal force or was it just by tensioning the pull cord they came out without any spinning/centrifugal force.

The alternative was the compression stroke on the engine was jamming it up.

I guess it's hard for you guys to offer advice without further investigation by me...... i.e buying a new starter mechanism and fitting it and trying to come up with more answers as to what the problem is, so we can finally solve the problem.

The other solution I'm loooking at right now is making my own fixed pulley which I'm going to securely fix to the crank/starter cup and then there won't be any pawls to fowl anything up

Any thoughts?

Thanks

[freepo]

I can sort of answer this right now, looking at the broken starter on my desk, it is clear how it works, it's not centrifugal force. There is a steel plate which somehow stays still as the cord is pulled, as the steel plate remains fixed and the rest of the pulley and pawls begin to rotate, a couple of little protruding lugs on the steel plate will engage with the pawls forcing them outwards, when they were fully extended and engaged with the cup flanges the force is sufficient to then turn the steel plate against it's resistance - quite clever really.

Perhaps what was happening was that I pulled the cord the starter spun around but the plate did not remain fixed so the pawls did not come out. Then as I was pulling the cord out fast, perhaps the plate suddenly fixed - the pawls came out and jammed onto the cup flanges.

So the answer would be to buy a new starter and make sure to engage the pawls and the engine was engaged before putting real force onto the starter cord.

[freepo]

However maybe my memory is failing me (it broke last summer) and maybe the pawls did engage and turn the engine as I pulled the cord and then something happened to jam the engine. - Now that I think about that, when I looked at the top of the engine today I did notice some damage to the engine casing (which spins around ) Perhaps something got jammed as it was being started, but then why no jamming when the engine was running, who knows, needs more thought, and maybe need to buy new starter and see what happens.

Sorry for the babbling post.

Any thoughts on this in general?

[The Natural Philosopher]

It wouldn't be the first time something has jammed in a pull cord system and buggered it.

get new parts, understand how it shpould work, and if it does it again because its crap design, fix to work, sell on e-0bay and get a decent one.

[Jules Richardson]

It's possible it's intentionally designed as a weak-but-replaceable link in the system, same way that the B+S engine in my lawn tractor uses a plastic gear on the starter motor - they get chewed up after a few seasons, but I can just walk into the local farm supply shop and buy one off the shelf cheaply. Better that than needing to replace the flywheel every so often, I suppose.

cheers

Jules

[Harry Bloomfield]

freepo expressed precisely :

It sounds as if you might be just yanking the cord. What you should be doing is pulling it gently to the point of compression, taking another bite and then giving it a firm pull.

[Mike]

ITYM.. pulling it gently OVER the point of compression.

[freepo]

This is correct. I didn't know how to start it before, but now I do and it is working fine.

I fixed it with a homemade fixed pulley which is now bolted to the top of the engine. I turn it beyond the compression point, wind my rope around it and pull. It's working so well I'm sure it would work equally well with a new shop bought retractable rope starter clutch & pawls system as was fitted originally, but I've made my pulley now and I'm in no hurry to buy a new pullstart for it.

A pity the instruction manual didn't explain how to start the engine in a way that would not cause damage to the pullstart.

[freepo]

My other (smaller) lawn mower has no problems starting the engine from any position. I guess it's because the engine is smaller, smaller compression easier to start.

[Dave Liquorice]

I hope you are *very* sure that the rope will *always* release from the pully as you turn the engine over. If it doesn't it won't half give your arm a yank and possibly pull you off your feet when the engine starts...

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Dave Liquorice" saying something like:

Or turn into a flail with amusing conseqenses for the ankles. Nah, such heeby-jeeby starter pulleys were dead common for decades.