2011 SR5 4WD - Thumping Sound at Low RPM

[Zufmeister]

Hey, everyone. I'm hoping you may be able to help me diagnose the source of a vibration/thumping sound my 4Runner started producing a few weeks ago. Between 1,000 & 1,400 RPM & at around 35 mph there is a thumping sound that is coming from the underside of my 4Runner.

I took it to the dealer and they initially though it would be caused by the exhaust system vibrating and hitting something but they ruled that out. They also don't believe it's the tires being out of balance, alignment, transmission, braking system, suspension, or steering system.

I can repeatedly generate the sound by driving between 30-35mph & the engine RPM between 1,000 & 1,400. The dealer tech said he could do the same when he test drove it but said he couldn't generate the thumping sound when it was up on the lift.

If the sound continues I do plan on taking it back to them for further investigation in 2 weeks.

I'm not even close to being a mechanic but to my ear it sounds like something vibrating at that specific RPM/speed.

Anyone have thoughts on what it could be?

 

[rdruss]

Thump, thump, thump, thump or thump ... thump ...thump ... thump?

 

[Zufmeister]

It's a quick paced thumping/vibrating sound. I can actually feel it through the drivers side floor whenever it occurs.

I had the truck out on the highway for a short trip this past weekend and it not only happened at that low speed but also around 65-70 mph when it was at low rpm.

It's starting to have an almost metallic sound to it. My guess would have been something was loose in the exhaust or a heat shield had come loose.