Metallic sound from rear of '06 DCSB

2006 DCSB, SR5, 4wd, 4.0, 6 speed manual, 308,000 miles...

Last week I noticed an intermittent sound coming from under the truck... it sounded like an exhaust heat shield that was loose and rattling. I just heard it a couple of times, so just made a mental note to check it out next chance I get.

I didn't drive the truck again until last night, when I started to go to work, before I made it a half mile, I was hearing the noise constantly below 35 mph.

It is a metallic knocking sound that gets faster as I accelerate... it is not dependent on engine speed, but is dependent on vehicle speed.

To describe the sound, it resembles something tapping the exhaust system, taps faster at higher speeds, slower as I slow down. Pushing the clutch pedal doesn't change the tapping, nor does pushing the brake, except it slows with the speed of the truck.

I did not notice any unusual vibration with the sound.

I lost my hearing in my left ear a couple of years ago, so it's difficult for me to pinpoint where a noise is coming from, but I'm reasonably sure it is from behind the drivers seat.

Just for reference, I had the universal joints and carrier bearing replaced about 60,000 miles back.

I'm guessing it has something to do with either the drive shaft or rear axle.

I went back home and drove my other truck to work... I'll pull the '06 into my shop tomorrow and see what I can figure out...

Any ideas or suggestions on specific things to look for would be appreciated.

Thanks- Bear

 

1. What about in 4x4. Still noisy

 

I didn't have time to check that... I've already done the ECGS bushing in the front a couple of years ago, so no needle bearing.

-Bear

 

If not drivetrain look at all the heat shields above the exhaust system as the mounting holes rot out and larger washers are required and then under the drivers seat that cat has a metal heat shield that usually looses the clamp and the 2 bolts. For a constant noise how about the front brakes are low hitting the metal tab squealers - that frequency is hard for many to pinpoint.

 

When I arrived home from work this morning, I pulled the truck into the shop and up on my ramps... it took me almost 3 seconds to find the problem...



The thin shield around the gas tank was bent and rubbing the drive shaft. When I saw it, I remembered running over a piece of tire tread on the interstate last week... it must have flipped up and caught the corner of that shield...

I'll call this problem solved... thanks for the suggestions.

-Bear