Two days ago I started hearing a banging sound that at first sounded like a rock hitting the undercarriage. Doesn't happen often, but after a few of them I knew it wasn't rocks.

Living in a small town we have a good mechanic but since he works on just about every make and model of truck he doesn't have anywhere near the amount of experience and exposure to Dodges that this group has, so I thought I'd check and see if any of you have an idea of what might cause such a thing. He has been able to get the truck to make the sound but hasn't tracked down the cause yet.

My beast is a 97 2500 4x4 with the Cummins and a manual transmission. Just about 200,000 miles. Hard worker, hardly ever complains but I've got to deliver a load of animals Monday on a trip that will take me over a 6,000 ft pass and cover 125 miles one way. Would love to get it sorted out before I need to head out.

Thanks for your help.

 

is it on any surface? of when on gravel or what not? only things i could thing to bang...would be like a control arm bushing thats shot and the arm is tappin on the frame, or a loose tranny mount...

 

I'd check the sway bar to ensure that the link isn't broken, allowing the sway bar to flop around. Also, check the front U-joint behind the wheel to ensure it isn't sloppy with play. Take a close look at the front suspension to ensure nothing is loose (shock absorber, etc.).

It could also be your tires throwing rocks, too. I installed new Michelin ATX tires and they tend to pick up gravel in the treads when parked. As I drive along, it will pitch the rocks out of the tires as I travel, sometimes after driving quite a distance (3 -5 miles or so), sounding like what you are describing.

 

I forgot to include that both Ray and I could feel it through the throttle pedal when the "bang" happened.

I only experienced it on gravel. It seemed to happen more often when I was backing up or going forward at slow speeds while jockeying the livestock trailer around. Ray drove it up and down a rough hill behind his shop to hear it the first time.

I'll ask him if he's check the transmission mounting and the control arm bushing and thanks for your reply.

 

Thanks for weighing AD. I'll make sure he's checked the sway arm. I know he looked at the U-joints and the shocks.

I would love it to be the tires and rocks but I'm thinking that's unlikely, moving too slowly and always at the same spot but boy would I love for you to be right about it.

I'll print out your comments and take them down when I go to town tomorrow.

 

thumping or banging under the driver or passenger feet is a loose lower shock bolt. torque to about 105#. the rubber bushing might have fallen out.

 

I want to thank all of you for your help. Turns out the problem came from another area, the body.

When the shop was working on the truck they noticed a couple of bolts loose on the fender near the hinge on the driver's side. Being the good guys they are, they tightened them up. Turns out a couple of the fender brackets are cracked and apparently tightening up the bolts caused those pieces to come in contact with each other and when the pressure built up enough they released with a "bang."

Loosening the bolts resulted in an inability to recreate the sound. The truck gets some down time around Thanksgiving and we have a very good local welder who will try to repair the brackets. If that fails, I'll hit the wrecking yard and look for a good replacement fender.

At the prices of today's new trucks it looks to me like a fellow could end up with monthly payments of anywhere from $750 to $1000 a month. I can get a lot of work done on my truck for that kind of money and at the end of it all, the new one and the old one will reach the same place.

I'd rather support my local mechanics and restoration guys than send the money to large corporations and banks so I'll just keep my pal running for as long as I can.

Thanks again, you guys are a great resource for a farmer who just doesn't have the time or aptitude to really get into the inner mysteries of his truck.