Harmonic balancers

[95suburb]

although i havent heard any noises coming from my harmonic balancers and dont see any sighns of separating, how long to harmonic balancers ususally last, and is it true that you should change them every 100k miles...

[Husker 6.5]

although i havent heard any noises coming from my harmonic balancers and dont see any sighns of separating, how long to harmonic balancers ususally last, and is it true that you should change them every 100k miles...

You won't "see" signs of separation until it is catastrophic, but here's what you can do to check.

Engine off. Remove tension from serpentine belt. Grab the crank pulley. See if you can rotate it either direction without turning the engine (radial play) or wiggle it back and forth (axial play). ANY looseness is unacceptable, and indicates inpending elastomer failure/separation. You can also hear one that's starting to go bad as a light thunking sound that changes with RPM that may sound like it is coming from the vicinity of the vacuum pump, but with a mech's stethoscope can be pinpointed to the HB.

There is no "milage" to replace them at, just a physical check while it's up on the rack for an oil/lube service is a good idea every time.

Perhaps the 100k you're thinking about is for the injectors, that's true.

Hope this helps.

Husker 6.5

[95suburb]

thank you, that definitely helps, I just wanted to make sure before I started buying parts I dont need

[Nick Witek]

Exactly how much looseness are we talking about? My truck has over 202K on it. i have to parts, just need to wait until next week for mechanic to get to it.

[Husker 6.5]

Exactly how much looseness are we talking about? My truck has over 202K on it. i have to parts, just need to wait until next week for mechanic to get to it.

Like I said in my post, ANY looseness radially or axially. With a new balancer, you will have a couple of thousandths play. If the elastomer deteriorates or debonds, you will have gross movement, 1/8" to 1" is not uncommon for axialy play (wiggle), and being able to rotate the balancer a clock position or two is not uncommon for radial play.

Husker 6.5

[jdcude]

My balancer failed after my alternator froze. I put in the new alternator and there was a funny rattling sound. I thought either the power steering pump was failing or the new alternator was bad so I pulled the belt and the alternator spun free and without noise, same for the power steering pump. I went on the internet and read of a few others experiences, and also as noted in the SSDiesel parts thet these balancers are a common failure. So I checked mine out and I noticed the balancer would rotate freely from bolt to bolt (4 bolts holding the "Pully" section of the balancer). You probably are aware that there are 2 parts to the "Balancer" with the "Pully" section being the primary offender from what I have read of others experiences. I also installed the 21 inch fan upgrade at the same time as the "Pully" section since I was that far into it.