Piece of puley broken off

[Werner]

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!

[Gary WA]

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

[john charlton]

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

John in same place same weather .

[Bob from Northport]

That has to change engine balance when running.

[Synchro909]

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.

[Ivan in southeast va.]

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

[old ugly]

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.

[Y-Blockhead]

Now is a good time to install the Murrey Harmonic Balancer you know you always wanted...

[bavArian]

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.

[jack backer]

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.

[Synchro909]

Originally Posted by jack backer

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.

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.

[mass A man]

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?

[Dodge]

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.

[larrys40]

Originally Posted by Synchro909

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.

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

[SAXBY2]

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

[rotorwrench]

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.

[ronn]

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

[Werner]

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.

[larrys40]

Originally Posted by SAXBY2

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

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

[Synchro909]

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.

[john charlton]

Hi Werner . My truck runs mighty fine with the same pulley damage you have no belt wear . No more unusual vibration that I can tell . I would change the ribbed belt you have on now and put on a regular smooth sided belt . Could be the ribs could catch the pulley damage ,just a thought .

John in a lovely sunny morning about to visit my good model A buddy Brian in my 1928 AF phaeton .Suffolk County England .

[Werner]

Originally Posted by Ivan in southeast va.

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

The reason for the break probably lies in the past. Two years and >5000 miles ago, the pulley banged violently against the traverse while we mounted the engine.

John Charlton] I would change the ribbed belt you have on now and put on a regular smooth sided belt. Could be the ribs could catch the pulley damage, just a thought.

That will not go well, I think. Because I have installed my alternator with a pulley that has been turned very small, the radius is too narrow for a non-toothed V-belt

[nkaminar]

Changing out the front pulley is about a 4 hour job. You have to get the radiator out of way which takes most of the time. You have to unbolt the front engine mount and jack up the front of the engine. Put some wood between the jack and the pan to protect the pan. Loosen the rear mount when you do that. Use a gear puller to remove the old pulley and a bolt to force the new pulley on. Be careful to line up the key with the keyway in the pulley. People have had issue removing the back half of the two piece pulley. A pulley machined from a solid block of steel can be purchased but they are expensive.