Harmonic Balancer or Transmission?

[asull85]

A few days ago I noticed a high pitched squeal coming from what sounded like underneath my truck as I was going slowly uphill or starting from a complete stop. Once on flat ground or once I reach about 20mph the squeal goes away. This morning I changed the belt, tensioner, pulley, checked the A/C compressor, power steering pump, water pump and alternator. All of those are in good shape. Which leaves me with the harmonic balancer or a transmission issue. The transmission is shifting fine but it does have the original fluid and filter. With a 164,000 miles its well beyond time to change it. I've seen a few posts about the squeal but nobody has seemed to pinpoint the cause. I'm planning on towing my camper in a few weeks so I'd like to get this taken care of before hand. Any insight would be appreciated.

 

[Flag Gibby]

If it always does it from a complete stop I would pull the serpentine belt, start the car, and put it in drive and let it idle/slowly go forward to see if it still happens. If it goes away then yes, it has to do with the belt and something causing it to slip; if not then it is coming from something else but I have never heard of a tranny making a squealing noise and still shifting good. Note: do not let the vehicle run for very long without the belt in place. However, I have had rocks get lodged into my brake shield that make squealing noises at low speeds, so I would have a good look at your front brakes too.
Also, if it is the harmonic balancer you should be able to tell by looking to see if the rubber on the front of it is good or not. Decent video of a balancer issue on our generation : https://www.youtube.com/watch?v=YaPyge-2DlU the 5 minute mark and around 7 minutes shows how easy it is to spot an issue with them even considering how little space there is to get at the balancer.

 

[asull85]

Looks like I'll be changing the harmonic balancer. It doesn't look too difficult but I may just send it off to my mechanic due to lack of motivation. Thanks for the help!

 

[pb3]

curious about how you resolved? i too have a '10 v6 4x4 with 95k miles. i replaced the belt, tensioner and idler and still have a noise.

 

[asull85]

It ended up being the front U-joint on the front drive shaft.

 

[Flag Gibby]

Interesting, I would have never guessed that... the u joint bearings must have been seized, but pretty noticeable upon inspection.

 

[asull85]

I never would have either. My mechanic suggested that might be the problem. He ended up doing the work as the U-joint was seized and needed to be cut out.