Here’s how I found out a delaminated harmonic balancer was the cause of my woes

Do you drive an older car and suddenly hear what sounds like lasers firing from under your hood? It’s intermittent, might go away when your car warms up, and increases in intensity and frequency under load. If you peek under the hood, you might notice a chewed up belt, too.

You might have a faulty, delaminated harmonic balancer/crankshaft pulley.

Here’s how I worked that out for myself.

Our family owns a 1995 Geo Prizm/Toyota Corolla with 170,000+ miles with a 1.6L 4AFE paired to a three-speed auto under the hood.

One day I started the Prizm up and heard the aforementioned laser sounds coming from under the hood. I peeked under the hood and honestly couldn’t find anything wrong.

The sound went away, and I was able to make it to where I needed to go in town and back.

The next day my brother used the Prizm and the laser-like sounds were now paired with the unmistakable squeal of misaligned or worn drive belts.

I sprayed the belts with water and the noise went away.

At that point, I thought my problem was a worn-out AC belt as, when sprayed with water, the squeal went away.

I had a spare AC belt in the trunk, swapped it on, and took the Prizm for a test drive.

To my surprise, the new AC belt got shredded up!

Also, the laser sounds returned.

That’s when I took this video below.

I also happened to look closely at the belts movement and found that the harmonic balancer attached to the crankshaft was wobbling back and forth juuuust enough to, when under load, misalign the belts.

Yeah, that’s not supposed to happen.

Googling around on a Corolla forum and I found out that this is a common problem.

This thread was useful.

To confirm my problem, I did what the above thread suggested and marked a white line crossing both the inner and outer parts of the pulley.

Then, by bumping the starter motor with a quick turn of the key in the ignition a couple of times, if a delaminated HB was at fault, I’d see the two lines seperate.

Here’s a recreation of what I saw below.

Line test

What happens is these harmonic balancers are actually a two-piece design with an insulating rubber between the two pieces. With wear, tear, and time, this rubber can separate from either piece and literally come apart.

This is my Prizm/Corolla’s delaminated Harmonic Balancer on the right.

The Harmonic balancer’s inner rubber has delaminated

Despite this issue your car can still run with a faulty harmonic balancer, but you may notice my aforementioned issues, belt squeal, chewed up belts, sounds, etc.

I bought a new one, pulled off the AC and alternator belt, zipped the old one off with my corded impact, slapped on the new one, put back the old belts, and started it up, noises gone.

I took a look at the harmonic balancer with the engine running and no more wobble.

And, after a few days of driving, no other issues cropped up.

So, if you hear laser noises or suspect a faulty pulley, you may have a delaminated Harmonic Balancer.

A word of caution, when listening and looking closely at the drive belts, make sure your hair, hoodie strings, or anything dangling in front of you doesn’t get in the way.


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