Piece of puley broken off
 

Hi folks,

today at 50 mph there was a hard bang from the engine compartment. A crescent moon piece about 1 1/4 inches long broke off the crankshaft pulley.


Unfortunately, the one-piece pulley is mounted. Since dismantling it is very time-consuming, I am considering continuing to drive with the damaged disc. I think the risk of the V-belt coming off is very small.


Does anyone have experience in this regard?


Many thanks in advance!

Re: Piece of puley broken off
 

might try to smooth the edges down a bit-not sure about the balance tho.

Re: Piece of puley broken off
 

I have one like that and no damage to the belt witch has not come off ( yet !!!)

John in same place same weather .

Re: Piece of puley broken off
 

That has to change engine balance when running.

Re: Piece of puley broken off
 

Werner, I have repaired a pulley that was like that but it would involve taking it off the engine so you might as well replace it. That said, I have driven a long way with a piece out of the pulley. To prevent the sharp edges of the break damaging the belt, I rounded them off a little and drove on. The missing piece is thin and small. It weighs very little and is close to the axis of the shaft so it makes no discernible difference to the balance of the engine.
There is also a two piece pulley available that can be fitted with the engine in the car but you'd still have to remove the broken one if you go that way.

Re: Piece of puley broken off
 

You got home and now I would have it replaced. Any idea what caused it to break?

Re: Piece of puley broken off
 

if you plan to use it for a while before you change it. like mentioned above try to smooth the sharp edges and carry a spare belt.

i bought an engine from an old fellow, the pully looked just like that, he told me he had driven it that way for years and never had an issue.
but
its best to deal with it when you get a chance.

Re: Piece of puley broken off
 

Re: Piece of puley broken off
 

Yes, it will change the balance of the engine. But I don't think it will be noticeable or considerably increase the wear of the engine because the part is relatively small, quite close to the center of rotation and the engine runs with a relatively low speed.


I would be more concerned about faster wear of the belt as the belt will press into the edges in the pulley with each rotation.

Re: Piece of puley broken off
 

The pulley broke from harmonic crankshaft vibration, there is a possibility that it has additional cracks.The original crankshaft pulley does not balance the crankshaft. Murray Horn in NZ makes a harmonic balancer pulley for the model A,reducing harmonic vibration extends bearing life.

No, I would not clean and run it,I would replace it.

Re: Piece of puley broken off
 

I have a different reason for it breaking. I think it had been cracked for some time and finally let go. My guess is that the pulley was damaged when the engine was fitted - easily done.

Re: Piece of puley broken off
 

I have to agree, I've come very close to tapping the pulley when hoisting/fitting engines. All it takes is a slight tap with all that weight of engine. Or... the toothed belt may be too thick/wide and riding up on the flange instead of bottoming out in the pulley and may have been very tight?

Re: Piece of puley broken off
 

You'll never feel the out of balance from that small piece that close to the crankshaft
centerline.
As for changing it, get a spare fan belt if it tosses the one on the car or tears it up
then put on the spare and drive home and change the pulley.
Drive it for the rest of the season and change the pulley over the winter if your worried
about it.

Re: Piece of puley broken off
 

I agree with backer and synchro ., although I think at some point the Pulley was Pryed against and being cast it is weak sideways and broke. I would just replace it before it potential frays then belt. There was and is no balance issue on the low rpm of the model a engine.

If you want to make it easier to remove cut all 3 webs with a sawz -all and remove the large end of the pulley and it will make it easier. You can vac the remnant dust and blow off at the end. Loosen rear mount bolts at flywheel housing and remove front mount stud nut and jack up front of engine as needed to remove.
You can remove the front u bolts if need be even with radiator in once nuts and lower plate are off and pulling them up slightly and pulling towars outside edge of car then removing spring crank bearing (what bolts sit on) at crossmember .
Cutting off webs will make this doable .
Have done this in car a number of times. This is why the 2 piece pulleys are preferred as long as it’s a quality unit.
Larry Shepard

Re: Piece of puley broken off
 

Larry and others, what is a quality 2 piece pulley? Is the screw type 2 piece ok vs the slotted 2 piece?

Re: Piece of puley broken off
 

I'm using the two piece Snyder's sells. The two piece that was on it was a poor reproduction made from zinc die cast. The seal surface was completely gouged out.

I like the two piece but it has to have some anti-seize so that the sleeve will come off after being on a long time.

Re: Piece of puley broken off
 

dont imagine any imbalance from that, however you could go 180 over and take a similar amount off the pulley on the same side........

Re: Piece of puley broken off
 

Good evening and thank you all for the calming driving experience!

I keep the pulley running.

I rounded the edges and flanks. In addition, two 5 gram pieces of wheel balance weights glued with JB.

Re: Piece of puley broken off
 

I’ve typically use the slotted ones from Brattons or Snyders and they have been good. I’ve got a variety box of older units some screw type and the older ones wolhert brand or quality aftermarket have been good as well.

Happy Model A Motoring!
Larry

Re: Piece of puley broken off
 

I had a screw on type two piece pulley at one stage. It didn't last long. Only a few weeks ago, I had the same thing happen as Werner shows and no one piece pulleys were available from the vendors. I used the stepped type. Time will tell.