What is causing my 2000 dodge caravan to make a thumping sound when I accelerate over 20mph?

Start looking at your tires one of them might have a hump…

Welcome to Fluther.

Have you run into or over any curbs or potholes lately? My expectation is that you have damaged the wheel to put it out of round just enough to be noticeable as you drive, but not badly enough to make the tire go flat.

Because of your description of how the problem increases with acceleration, it certainly does seem to be tire-related.

Thank you for your quick response. Did not any hit any curbs, but the roads are horrible due to the crazy New England weather. It sounds like a tire is going to fall off. And it has gotten worse over the last day.

I had a tire whose tread began to delaminate. It was impossible to see with the naked eye, but there was a very specific speed at which the thumping would kick in. This was just a defective tire, not due to any particular road damage.

Tires are fairly new – just got them rotated at last oil change – I did try to go look at tires, but cannot see anything and sound does kick in at very specific speed as you said. I start to hear noise as I hit 20mph each time I drive. Hmmmm

Yes, my defective tire was pretty new, too. I thought I might be able to file a warranty claim, but it turns out that tire warranties are prorated, so I would have only gotten $10 off another of the same tire. I opted to upgrade to a better tire.

…it might also be one of your studs is loose…

To check your tires for humps, you just need to run our hand on it and you should feel it even i you cant see it.
I am assuming you have tires with decent thread depth of course.

These are thing you can eliminate before going to the pros.

Thanks will do – Just drove my van sounds like a chugging locomotive as I accelerate – sounds like noise is right under my feet

Welcome to fluther. You may have lost a wheel weight in which case the tire is out of balance. Check the rim to see if you can see a spot that’s not aged as much as the rest of the rim.

Blown rod in your cylinder? Right under your feet can be the exaust, too.

went to my mechanic – it was the hub and bearing?!!

That was going to be my next response.

This happened to me once and had mechanics at two separate places trying everything to figure it out.

It turned out that the lug nuts after tire change were not tightened sufficiently. Since you mentioned recent tire rotation, it might be worth checking out and perhaps have them tightened with the pneumatic device rather than manually.

Even tho this happened to me over 20 years ago, I’ve never forgotten that sound or the horrible uneasy feeling as I drove.