Buick 91

91 Buick Park Ave

Developed a mechanical scraping noise. If you take the drive belt off the noise is not there. So I replaced the power steering pump, alternator, water pump and AC compr. I am now thinking it is the crankshaft balancer assembly.


What about the idler pulley(s)?

The harmonic balancer is a common failure on the older 3.8 Buick motors with high miles / old. It’s an easy replacement (though you’ll need to adjust the crank sensor once you install the new unit). Before you throw any more money at the problem, make sure the pulley is really the issue; you’ll be able to see the rubber separated from the pulley, or simply listen through a piece of hose at the idler / and balancer to see which one is making noise. The idler pulley bearing is less than $20, the whole assembly w/ tensioner is about $125 and you can get a harmonic balancer for $50 on EBAY, or about $100 at the parts store. Good luck.