Crank Pulley question

[Dazzak]

Hi all, i have a 172 phase 2 which has had intermittent clattering noises finally resulting in a non start (flat battery) and a hell of a squeal on idle, im no mechanic but have traced it down to what looks like a broken crank pulley, spins up fine on idle until steering is turned then it literally stops whereas you can still see the inner metal part spinning.

My query is what would cause this or is it just wear & tear (106,000 on clock) does it cause any other damage also anyone know where i can get a replacement cheaply and quickly as booked in for track day this saturday

Many thanks in advance (excuse my lack of knowledge)

 

[MicKPM]

It is rare but possible - The two metal races are linked with a damping rubber joint which fails over time. If it's just spinning then you're quite lucky but it will need replacing carefully as the bottom crank sprocket is a floating setup. Simply undoing the crank pulley bolt and replacing the unit will most likely result in incorrect timing. Ideally, you want the bottom end and top end locking off to then safely be able to release the crank bolt and replace the pulley.

Mick

 

[Dazzak]

Cool, appreciate prompt reply....are they likely to be all the same on 172s as may have to fit second hand one...nowhere seems to carry in stock and waiting time means no track day for me..........clearly not a job for me personally though

 

[MicKPM]

Yes, they're all pretty much the same but there are about four or five different types... not that it'll matter to you, for the purpose of this exercise at least.

 

[Dazzak]

So effectively I could get a second hand one and just get it fitted which should see me through the weekend? Appreciate the advice

 

[MicKPM]

Yes you can but see the above warning about timing slip on the crank if you just unbolt it and switch the pulley.

 

[Dazzak]

It won't be me replacing it, it's over my head and not worth a gamble...thanks