Review on GM 12621646 Genuine Parts Crankshaft Balancer by Lance Jenkins

After years of strange cold start noise, replacing this part has resolved the issue. It wasn't the belt, alternator, battery and tensioner. The balancer consists of two parts separated by a rubber ring. It looked and sounded like the original rubber ring had deteriorated and something had fallen out. This caused the rubber ring inside the outer balancing ring to slip when the car was started. This caused a rapid chirp on cold starts. I believe the problem went away as it warmed up as the rubber ring swelled. Now that I know, that's a pretty good indicator that it's time to change the balancer.