Why is my engine pulley wobbling and making a grinding noise?
A wobbling engine pulley is often caused by aged, degraded rubber in components like the harmonic balancer or crankshaft pulley failing completely, which can throw the belt and cause grinding sounds underneath the car. This makes it difficult to determine whether the failure stems from normal wear on old parts or a component installation error.
What the numbers show
Counted from the threads quoted below. How we count
- People have been saying this in most months since September 2026.
- This comes up 11.7× more often in r/AskMechanics than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
Why is my engine pulley wobbling and making a grinding noise?
- 1visually inspecting components for movement between the crank and outer pulleyDid this help you?
- 2Replacing the failed harmonic balancer and inspecting the engine system for related wear or secondary failures.Did this help you?
- 3limping the vehicle to a shopDid this help you?
- 4fixing it yourself by purchasing tools like a 1/2 impact and a 4 lb hammerDid this help you?
- 5Asking mechanics online for visual confirmationDid this help you?
- 6Asking a mechanic friend with proper tools to perform the inspection and repair.Did this help you?
- 7Taking the vehicle to a professional mechanicDid this help you?
- 8Finding a smaller belt in the meantime to bypass the AC clutchDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Went to fill the oil as you do once a week in a sh*tbox and I noticed the front pulley wiggling andy belt about to throw off.”source ↗
“The bolt seems tight still, and there's metal shavings everywhere.”source ↗
“I installed a new seal but the balancer now has a slight wobble. What should I do”source ↗
“it looks like the belt around the pulley is wobbling a little bit and getting underneath the car makes it sound a little bit more like grinding.”source ↗
“So I got the tensioner installed and the belt went to start it and next thing i know the crank shaft pulley ( the outer part ) came off completely . So wondering if this was due to aged and degraded rubber or if it was a user error ...”source ↗
“Does this harmonic balancer look normal or is it wobbling excessively? Just bought the truck and was looking it over and noticed it”source ↗
“Ill have to wait for my mechanic buddy to come pull the balancer and everything. I don't have a puller tool or know how to use one really”source ↗
“I got home from my long commute today in my ‘21 Corolla with 117k and when I started my car again, I heard a tapping noise with a whirring.”source ↗
“After looking, it appears the tensioner is moving excessively..? And maybe the AC condenser pulley might be wobbling?”source ↗
“I know I’ll have to take it in but I just need to know what I’m looking at here.”source ↗
“Looks like bearing but also double check it's not the lower ball joint.”source ↗
“Shake from side to side too. If to wobbles that way too it's probably the bearing.”source ↗
“Wheel bearing or upper/lower ball joint”source ↗
“Yes it wobbles from either side”source ↗
Where this came up
People with this problem also raised
- 3Is a car totaled if the engine moved?
- 74Why does my car make a loud rattle when starting the engine?
- 2Camshaft timing off by half a tooth after rotating engine
- 5How to check for bent pushrods in an old engine
- 7Engine still squeaking after replacing water pump and tensioner
- 12Did my timing belt slip or did I mess up the install?