Friday, May 30, 2014

Checking your harmonic balancer

One of the common problems with aging redblock volvos is the harmonic balancer slipping. The harmonic balancer is the pulley coming off the crankshaft on the front of the engine that drives the accessories via belts. It's not a solid pulley, it consists of an inner and outer steel piece with a rubber spacer between them to reduce vibrations. Over time the rubber degrades and the outer pulley slips or wobbles. This can cause noise and vibrations, make the belts slip, and eventually fall apart.
The reason I'm posting this is that this is very easy to diagnose and since all redblocks are pushing at least 20 years old it's something you should be aware of if you own one. All you have to do is use some chalk, paint pen, marking crayon, etc and mark the inner and outer parts of the pulley. Below are pictures of how I did it. It doesn't have to be very exact, if it's worn it will slip a lot. Once it's marked anytime you have the hood open take a look and see if they're still lined up.

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