(‘85 3B) Sheered off PS Pulley (1 Viewer)

[quadrunner91]

Hey, I was wondering if anyone has seen this happen before, or knows why it happened.

All six bolts that hold the secondary pulley to the main crank pulley, sheered off while driving at highway speeds.

I found a replacement pully on eBay, but I have absolutely no idea what would have caused this!

My only guess is that the belt was too tight and fatigued the bolts, but that seems rather unlikely.

 

[sodafeld1]

Could only imagine the bolts or some were loose, and spinning frequently at speed and force, with a tight belt eventually fatigued and snapped them. Especially upon start up. Yikes.

Diesels rattle around heaps, need everything torqued down. Maintenance issue I would say.

 

[Eurasiaoverland]

The front crank pulley is a harmonic balancer - it has rubber bonding between the inner (inertial mass) and outer sections belt lands to dampen cylinder impulses. When the rubber hardens and the bond with the metal parts breaks down, bad things happen. Make sure the pully is runing true when the engine is running, to rule out a failing harmonic balancer.

 

[sodafeld1]

The front crank pulley is a harmonic balancer - it has rubber bonding between the inner (inertial mass) and outer sections belt lands to dampen cylinder impulses. When the rubber hardens and the bond with the metal parts breaks down, bad things happen. Make sure the pully is runing true when the engine is running, to rule out a failing harmonic balancer.

Yeah I have heard of the harmonic balancer rubber perishing but have yet to see a main pulley which is stuffed. But have not honestly looked for it. Some folks get them rebuilt or re-glued which seems an expensive process with timing kept in mind with the alignment. A replacement harmonic balancer is not cheap either. Crucial part indeed.

 

[quadrunner91]

The front crank pulley is a harmonic balancer - it has rubber bonding between the inner (inertial mass) and outer sections belt lands to dampen cylinder impulses. When the rubber hardens and the bond with the metal parts breaks down, bad things happen. Make sure the pully is runing true when the engine is running, to rule out a failing harmonic balancer.

If I’m understanding correctly, the pulley pictured in my photo doubles as a harmonic balancer?

I never would’ve guessed just by looking at it!

 

[sodafeld1]

No, harmonic balancer is the main pulley coming off your crank.

 

[Eurasiaoverland]

If I’m understanding correctly, the pulley pictured in my photo doubles as a harmonic balancer?

I never would’ve guessed just by looking at it!

Yes, the pictured pulley with the sheared-off bolts in is a harmonic balancer.

 

[sodafeld1]

Oh wow! sorry my bad, second look at my skim glance it is indeed your main pulley, ouch.

 

[bj70bc]

cool
musta got loose