I started this thread a few days ago due to a strange vibration from the front end of the truck https://www.ford-trucks.com/forums/9...vibration.html

My mechanic is now telling me it is te harmonic balancer on the engine. Do these things actually go bad? How can they go bad? Will that create a strange vibration upon acceleration? THANKS!

 

I believe though you should be able to feel the vibrations while sitting in neutral and brining the RPM up.

Yes by the way, they do go bad, how often, I am not sure. THere is a thin rubber between the inner and outer ring that sometimes dry rotts. Then the outer pulley no lnger runs true to the inner piece.

You should have enough room to crawl under and put your hand on it and see if you can move it.

 

I am interested if you ended up replacing your harmonic balancer. If so, did it fix the problem? Did you look at it while the engine was idling to see if it wobbled or moved when running?

 

I agree with Pat,it actually should vibrate all the time with RPM
Sometimes they wobble but not always.If it slips on the hub some it will be out of time with the rotating assembly and cause a vibration
A bad harmonic balancer should not be ignored it can cause internal engine damage and even break the crank shaft

 

Yes, we did replace the harmonic balancer and the problems all went away.

 

Thank you for the update!!!! Congrats on the repair!!

 

When I replaced the engine in my truck last spring, I replaced the balancer just because I didn't want to deal with problems like this.
Old one was still good, but it got scrapped

 

Glad it fixed the vibration!
I believe my balancer is shot as well. Vibrations can be felt while sitting in neutral and bringing the RPMs up between 1100 and 1500. Not before or after that range though. Thought I might have an injector starting to go out so another forum member performed a buzz test, cct and perdel check on the motor with AE. No definate red flags came out of it. It did fail cylinder #8 which many do, but perdel reading for that cyl only showed around a 3% reduction with others between 0 and 2%.

So, I checked the balancer to see that it is not moveable or loose at all with the motor off. However, when the engine is running the balancer has a significant wobble which is very noticeable if you keep your eye on the balancer with a view of the silver metal CPS bracket. As it turns it travels in and out (closer and further from) in relation to and from the CPS bracket. That's why I asked if you viewed the bad one with the engine running?