Harmonic balancer, is it bad?

[Kollin Syverson]

While pulling the radiator out for a good cleaning, I checked my crankshaft balancer. The rubber doesn't look too bad, but should I be able to rotate it back and forth? It does not move much, but is fairly easy to move. I am thinking as long as I am this far, I may as well just change it. Any thoughts?

[DmaxMaverick]

How far is it moving?
Is it slipping on the rubber, or is it the rubber's elasticity that is allowing movement?

A good HB will allow slight movement of the outer ring with a lot of resistance. If it moves easily, it's probably separated from the rubber, or the rubber has degraded or softened, which is bad.

Hard to say without a hands on. If there is any doubt, replace it, without hesitation.

[tanker]

1994 with original unit and a lot of miles :rolleyes: I'd replace it. Good insurance. ;) I broke my crankshaft without warning, but we suspect the balancer was the culprit. I'd replace it. smile.gif

[tom.mcinerney]

There are two sepatate stacked units with different characteristics. The crank pulley, which drives the accessories thru serp belt, is so loosely coupled thru a 1" ring of rubber [designed for smoothing pulses between crank and crank-driven accessories] that it'll rotate 1/8"-1/4" by hand. The HarmonicBalancer has only a 1/8" thick rubber ring, this is stiffly designed to 'dampen' or limit, the tendency for the crank throws to be instantaneously overrotated [to twist too far] at the moment of combustion on the power stroke. One cannot budge the outer ring of the HB, too rigid.
Either the HB, or the crankshaft's accessory-drive pulley (bolted to the front of the HB) can cause the crank to crack if deteriorated. If the HBs rubber is dried and cracked, if oil soaked, or if bulging out at any point around edge, it is prudent to replace. When the crank pulley wears, it can rotate so far that the outer ring contacts stops on the inner, transmitting destructive pulses; cranks tend to crack thereafter...

[Kollin Syverson]

So your saying it is the crankshaft pulley that is usually the culprit that breaks the crankshaft when it fails.

[CleviteKid]

I don't think there is enough data to say that either the harmonic balancer or the damped crankshaft pulley is responsible for "most" of the crankshaft fractures. Either one CAN cause crank damage, but the harmonic balancer is, in my opinion, the item that is most likely to cause crank damage as it deteriorates with age and exposure to the elements, including the ones we use to feed, lubricate, and clean our engines.

Dr. Lee :cool:

[bobt]

After reading your post yesterday, I was doing some maintance today so I decided to check my pulley and balancer. I disconnected the belt and tried to move or rotate the pulley and balancer in any direction. Neither one would move and both look like the rubber sections are in excellent condition. The vehicle has 85,000 miles but the new long block installed by the dealer in 2000 has only 20,000 miles. However, I think the pulley and balancer were probably transferred from the old engine. I didn't see the new engine prior to installation, but service guy told me long block doesn't come with all the external items such as glow plugs, injectors, etc. and they use the items off the old block. Anyone else out there bought a GM long block that has seen exactly what additonal,if any, parts come with it? If your pulley or balancer has movement in it, sounds like it has some excessive wear.
Bob

[damork]

For the ease of replacement and low cost it was a no brainer for me to install new at about 143k miles. I think I paid about $60 for a new GM unit (www.teamchev.com). The unit looked good while still on the engine but I could find cracks I couldn't see once it was off.

[Kollin Syverson]

Well, while I had it this far I replaced everything. New Crankshaft pulley, $174.00 ( I think I got screwed on this) new front seal $11.00 and new Harmonic balancer $111.00 ( I think I got screwed on this too). Moral of this? Even if I got screwed on the parts, its still way cheaper than a broken crankshaft.