Broken Balaner Survey

[Katoom]

I would like to try and pinpoint the root cause of broken balancers.

In my case, the pulley bolts rotted and broke. Luckily I caught it before it flew apart and I was able to remove the balancer, extract the bolt remains, then replace them with Grade 8 machine cap screws, lock washers and loctite.
I now have 280,000km on a stock balancer with no trouble.
Are the pulley bolts the root cause, or does the main balancer bolt fail first....causing the aluminum balancer to fail?

If you have had a balancer fail, please post what happened........has anyone ever broken a balancer, but still had the main bolt still intact?

If everyone that has had a balancer fail found that the crank bolt was gone or broken, it could be that the bolt should be a maintenance item and replaced every 4 years or so........

[Bill McNeil]

Katoom,

There are several reasons that balancers fail in our cars. First is the actual design of the balancers, and the fact that two different metals are used to make it. The second cause is the short keyway on the crank, which doesn't extend out far enough, thus causing additional strain on the balancer. Third is the overall load it undertakes from these cars. You have the strain from the blower (being the biggest strain compared to other cars), power steering, A/C and alternator all on the outer portion of the balancer, all the time. The crank bolt can also be a weakness, especially considering the bolt Ford used for SC was later found to be a weaker grade than was used in other applications, including n/a 3.8L engines in Mustangs, etc.