When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
In the process of chasing down a metallic "clinking" noise in the front
of the motor in my '75, I found that both pulleys on the damper were
cracked thru the holes in the hubs. They were totally ready to
shatter, probably with very expensive results. I have new pulleys coming
but am nervous about just putting them on with no idea why the others
failed. All bolts were torqued correctly and alignment looked good.
Anybody have any ideas or seen this before ?
TIA
Larry
In the process of chasing down a metallic "clinking" noise in the front of the motor in my '75, I found that both pulleys on the damper were cracked thru the holes in the hubs. They were totally ready to shatter, probably with very expensive results. I have new pulleys coming but am nervous about just putting them on with no idea why the others failed. All bolts were torqued correctly and alignment looked good.
Anybody have any ideas or seen this before ?
TIA Larry
This is not an uncommon problem (or symptom - good catch!) for the crank and water pump pulleys. I believe that GM even included a reinforcement plate that could be added to help distribute the load more equally with some pulleys. The secret is to thoroughly examine the hubs of the pulleys any time your remove them and replace any that are suspect.
Pontiac Lower pulley reinforcement ring
As far as causes go, I would guess the primary factor leading to early fatigue is running belts too tight, followed by pulley misalignment, the material the pulley is made of and finally the distance between the pulley groove and the point on the pulley that bolts to the balancer/water pump. Sheet metal pulleys are more prone to cracking than cast pulleys, but cast pulleys do crack as well.
AMC water pump pulley...
SB Chevy water pump pulley...
Sorry, I just couldn't find a good picture of cracked-crank pulley! As you probably well know, the cracks in the crank pulley are exactly the same... results may be different, but the cracks are the same.
Mine did this after I dropped the clutch a little hard at a red light and , started knocking. The only way I found them was a metallic looking dust trailing across the pulley. I think I still have them.
This is not an uncommon problem (or symptom - good catch!) for the crank and water pump pulleys. I believe that GM even included a reinforcement plate that could be added to help distribute the load more equally with some pulleys. The secret is to thoroughly examine the hubs of the pulleys any time your remove them and replace any that are suspect.
Pontiac Lower pulley reinforcement ring
As far as causes go, I would guess the primary factor leading to early fatigue is running belts too tight, followed by pulley misalignment, the material the pulley is made of and finally the distance between the pulley groove and the point on the pulley that bolts to the balancer/water pump. Sheet metal pulleys are more prone to cracking than cast pulleys, but cast pulleys do crack as well.
AMC water pump pulley...
SB Chevy water pump pulley...
Sorry, I just couldn't find a good picture of cracked-crank pulley! As you probably well know, the cracks in the crank pulley are exactly the same... results may be different, but the cracks are the same.
Good luck... GUSTO
Thanks Gusto. Not too reassuring that GM knew of the problem to the point that they provided a band aid. I have two of these cars, now I can worry when I drive them both.
Thanks Gusto. Not too reassuring that GM knew of the problem to the point that they provided a band aid. I have two of these cars, now I can worry when I drive them both.
Larry, honestly I don't think I would worry a lot about it. The key is to watch belt tension and don't over do it. I have seen more than a few pulleys that never showed evidence of a problem until they were removed and minor cracking was noticed.
If you are concerned, I would remove the pulleys you're worried about and bead blast the centers to examine them closely for evidence of cracking. If you find none, repaint and reinstall them. Unless you plan some high rpm shifting, like over 6k, with proper tensioning, they should last for tens of thousands of miles.
You could also take them to a machine shop, particularly the balancer pulley, and have them machine a reinforcement for the pulley. It shouldn't cost much and would surely add years to the life of the pulley.
Larry, honestly I don't think I would worry a lot about it. The key is to watch belt tension and don't over do it. I have seen more than a few pulleys that never showed evidence of a problem until they were removed and minor cracking was noticed.
If you are concerned, I would remove the pulleys you're worried about and bead blast the centers to examine them closely for evidence of cracking. If you find none, repaint and reinstall them. Unless you plan some high rpm shifting, like over 6k, with proper tensioning, they should last for tens of thousands of miles.
You could also take them to a machine shop, particularly the balancer pulley, and have them machine a reinforcement for the pulley. It shouldn't cost much and would surely add years to the life of the pulley.
Good luck... GUSTO
Thanks for the info Gusto,
I found the pulleys on E-bay (used) and rec'd them yesterday. Bead blasted them and both are cracked, Not as bad as my original.
I have been thinking about welding the cracks and making the reinforcement as you suggest. Your opinion on welding ??
Larry
Thanks for the info Gusto,
I found the pulleys on E-bay (used) and rec'd them yesterday. Bead blasted them and both are cracked, Not as bad as my original.
I have been thinking about welding the cracks and making the reinforcement as you suggest. Your opinion on welding ??
Larry
Honestly, without actually seeing the pulleys and the cracks, I think it's a conversation I would have with a qualified machinist in your area. At the very least he (or she) may have a suggestion that provides a better solution. The metal is pretty thin, so at the least I think I'd be looking at TIG welding it.
You may also find that new pulleys are available. Do you have the part numbers of the correct pulleys? Can you tell us what pulleys you have on your engine? Power steering, AC, alternator, air pump? I.E., Harmonic balancer pulley - 2 groove, 6 1/2" outside diameter...
Honestly, without actually seeing the pulleys and the cracks, I think it's a conversation I would have with a qualified machinist in your area. At the very least he (or she) may have a suggestion that provides a better solution. The metal is pretty thin, so at the least I think I'd be looking at TIG welding it.
You may also find that new pulleys are available. Do you have the part numbers of the correct pulleys? Can you tell us what pulleys you have on your engine? Power steering, AC, alternator, air pump? I.E., Harmonic balancer pulley - 2 groove, 6 1/2" outside diameter...
Good luck... GUSTO
Hi Gusto-
My goal is to find NOS pulleys, 2 groove alt and a/c GM#346300aa,
and single groove PS add on pulley GM#346290ab. There are a lot of
used ones out there but hard to tell if they are good until they are
bead blasted and in my hands. I've spent many hours on the internet
searching but haven't found any more yet that I'm willing to take a chance on...I haven't tried yet the forum "for sale/wanted" section.
Going there now. Thanks again!
Larry
Hi Gusto-
My goal is to find NOS pulleys, 2 groove alt and a/c GM#346300aa,
and single groove PS add on pulley GM#346290ab. There are a lot of
used ones out there but hard to tell if they are good until they are
bead blasted and in my hands. I've spent many hours on the internet
searching but haven't found any more yet that I'm willing to take a chance on...I haven't tried yet the forum "for sale/wanted" section.
Going there now. Thanks again!
LarryS
Larry, you might try and give Paragon a call (1-800-882-4688). They have a pretty in-depth selection of used and reconditioned parts.
It looks like Paragon may have the add-on HARMONIC BALANCER P/S PULLEY (My 1982 Corvette Parts and Illustration Catalog lists this for the 1971-1975 w/350)
GM Part Number: 14023158
Harmonic balancer P/S add on pulley, all w/350, 1 groove, 6 11/16" O.D. Reconditioned original. photo courtesy Paragon Corvette Reproductions https://www.paragoncorvette.com/p-35...ps-pulley.aspx
Cracked damper pulleys....Why?????
As you probably well know, the cracks in the crank pulley are exactly the same... results may be different, but the cracks are the same.
