Hello. I have a 2011 4runner limited awd. Makes a loud rumbling sound at speeds between 22mph and 30mph. And at 55 to 60 mph. Only when feathering the gas, at those speeds, not when I accelerate hard, won't do it. Has 130000 miles had it since 79000 miles. For 4 years, towed a Nissan ALTIMA on tow dolly to Florida once. Changed front and rear diff fluid 2 months ago. Rear diff fluid looked? Transfer case changed also.Been doing this sound for 4 months. Also installed used propeller drive shaft from 2014 4runner with 75000. Greased it up good also. NO CEL. Any advice would be appreciated. Thanks, big fan, always recommended...
First, I'd check the motor and trans mounts. Every drivetrain will create vibrations, but it sounds like you've been maintaining yours and they shouldn't intrude to the cabin. If that gives no solution, I'd put it up on jackstands, run the engine and see if the driveshaft is vibrating and creating the rumble.
Thanks for your reply. I forgot to mention I changed the rear diff drive shaft because there is a TSB on it. Also lately its been doing the sound when cruising down on flat roads from 25mph down to 20mph it will briefly rumble around 23mph to 21mph without giving it gas. I also removed both drive shafts and checked for play on the pinion, but there was gear oil in Diffs, so I couldn't really tell.