rattling or clanking sound under 1500 rpm

[greatAEorion]

Just the other day my 91 park ave stated to make a rattling sound when I stated it up. it does it between idle and about 1500 rpm. I grabbed the belt between the alt and a/c and it moves about 6-8 inches and stops and when it stop it makes a metal to metal sound. is this normal ? any suggestions?

[HotZ28]

It sounds like it is time to replace the harmonic balancer This balancer is made up of an inner hub and an outer hub separated by a rubber insulator ring. The balancer is constructed of two metal pieces connected by a rubber spacer. Look for, visible cracks or warps on the balancer, wobbling pulleys when the engine is running, or improperly timed/running engines due to slipped outer ring. If you can rock the outer hub back and forth, yes it is time to replace it!

[Alibi]

I second a bad harmonic balancer. When you get one, buy new--a junkyard balancer is just that: junk.

Another possibility would be a worn belt tensioner, but remove the belt and check for slop in the balancer first as I'd say it is your best bet.

[greatAEorion]

yep the outer hub moves back and forth. It is parts store time agian. thanks for the help!!

[HotZ28]

And may the stand by your side!

[Alibi]

The HB bolt is 24mm (I think), and you will need a really long breaker bar (aka long hollow pipe) to get the bolt loose. You may want to search the forums for more suggestions as it is difficult to do without a large impact wrench, but it is still very do-able.