16v Crank Pulley

[sri_130]

I used to rock an OEM style pulley. The one with the rubberised goo that connects the actually pulley to the inner bit that bolts to the crank.

Somewhere along the line, I switched to a solid pulley. Some billet thing, but I can't think why I did that.

The rubbery bit must be some sort of harmonic balancer? so would be of more benefit than a solid one?
My crank has had to be ground and the journals were scarred after only 200 miles on a turbo build. Wondered if this pulley might have contributed to that. It was all shiny and new before.

[welshpug]

they are a harmonic balancer of sorts however they will have little effect on a small petrol engine really, certainly wouldn't cause any bottom end issues on a TU from beign a solid lighter weight item.


where this can cause issue is on the more modern powerful Electronically controlled diesel engines as the power events are rather more violent in them than a small petrol engine, especially at peak torque, hence the use of dual mass flywheels as well to damp up the whole assembly, its well known for gearboxes to not last very long in some applications when a solid flywheel is used.


your bearing issues will have been caused by oil supply issues, be it low oil or oil surge, or cooked oil.

[Chipwizards]

It absolutely is a harmonic balancer, but it's main contribution to engine longevity is to reduce the impacts of torsional forces on the oil pump and chain. I have seen several high-revving engines with alloy pulleys break up the gears in the oil pump; TUs, XU10s and supercharged minis too.

If you've had bearing problems there's some other reason for it, but I'd recommend keeping the HB unless you are going dry sump with a belt drive.

[Gabbastard]

Id always assumed it was to damp the effect of the a/c unit kicking in and that was perhaps why the other engines had solid pulleys.

[axsaxoman]

I suspect it was to quieten the inherent knock from the engines at idle
but yes that is not your problem

[smokeyshiva]

Do you have any photos?

There were two types of crank pulleys/oil pump sprockets I found when rebuilding one of my engines. One that had a separate sprocket/spacer and one that was one-piece.

The crank pulley they slid onto the other half of the woodruff key on the crank.

I never saw a bit of rubber goo as you're mentioning - care to explain more?

[smokeyshiva]

do you mean the aux belt pulley? if so the billet ones i've used have never had a rubber seal/gooey bit on them.. Pug1Off.. Spoox etc

[VeiRoN]

Yes the crankshaft pulley,I have the solid aluminium one and now strongly considering going back to the OEM one after reading Chipwizard.

Originally Posted by Chipwizards

It absolutely is a harmonic balancer, but it's main contribution to engine longevity is to reduce the impacts of torsional forces on the oil pump and chain. I have seen several high-revving engines with alloy pulleys break up the gears in the oil pump; TUs, XU10s and supercharged minis too.

If you've had bearing problems there's some other reason for it, but I'd recommend keeping the HB unless you are going dry sump with a belt drive.

Are you talking about engines that make peak power above 8k?