Thread: 2.7 TDV6 Crankshaft Pulley (Harmonic Balancer) Runout

Not sure on the pulley but the crank has an end float tolerance of only 0.3mm or thereabouts. I assume when you mean runout you are talking about radial runout (I.e. measured from the centre of rotation to the OD of the pulley (perpendicular to axis of rotation) and not axial wobble (parallel to axis of rotation).

I would guesstimate that 0.4mm may be too much, especially as it’s a machined item.

It is the lateral runout, or also referred to as axial runout, that I am measuring on the front face of the outer ring of the pulley. Not the radial runout.

I would expect some runout as the inner hub and outer ring are bonded together with rubber.

But haven’t seen any specs on what is acceptable.

Originally Posted by DiscoDB

It is the lateral runout, or also referred to as axial runout, that I am measuring on the front face of the outer ring of the pulley. Not the radial runout.

I would expect some runout as the inner hub and outer ring are bonded together with rubber.

But haven’t seen any specs on what is acceptable.

Agree. The rubber bonding is what I was thinking would cause some deviation. I wouldn’t worry. Good idea for replacing it however just to keep it fresh.

I definitely subscribe to the theory that a bad crankshaft damper can be contributing to crank flex and ultimately failure, and the fact that LR don’t appear to have a runout tolerance stated is a concern. In my opinion, it really should be replaced when the timing belts are done.

GM have a spec on this for the Camaro V8 and state that up to 0.4mm is acceptable, but above this then you need to replace. So on this value my new one is already at this upper limit from new - hence the concern.

It is tricky to see clearly, but a slo-mo video taken from above will pick up how much wobble the crankshaft pulley has.

I don't see it as a harmonic balancer as it's not keyed to the crank, more of a dampened pulley. I'd be more worried of it misaligning the serp belt and shredding it.

Probably best referred to as a crankshaft damper. The outer ring is the inertia mass element to help cancel out vibration forces, and the bonded rubber acts as the energy dissipating element to absorb the vibrations.

Whilst it is not keyed to the crank, it is locked in place using 6 bolts. As you note though, it is not technically a balancer as it does not include any external balance weights and so can be put on in any position relative to the crank.

Harmonic balancer, crankshaft damper, torsional damper, or vibration damper are terms that all get mixed up together, so just added to help in any future search engine use.