Strange noise under hard acceleration

S

ssmalley41

Member
I need some help. I noticed today that under hard acceleration there is a strange clunk or rattle coming from somewhere under the truck. It's a 2013, 4.0, 4x4, double cab, automatic with around 75,000 miles. It's bone stock, no mods. I've seen a lot of stuff about driveshaft noise, but this is not a constant noise. I get the noise briefly when accelerating hard up to 40mph, and only on or after the initial downshift. After that, it seems normal. Any info at all would be appreciated. Thanks.
 
I think I'm understanding... you take off from a stop with constant acceleration and as soon as you let up you hear a clunk happen. You notice no clunk at the immediate acceleration or during acceleration only when you let off the peddle after reaching your desired speed. Is that right?
 
OR17TRD said:
I think I'm understanding... you take off from a stop with constant acceleration and as soon as you let up you hear a clunk happen. You notice no clunk at the immediate acceleration or during acceleration only when you let off the peddle after reaching your desired speed. Is that right?
Click to expand...
No, immediately after pushing the pedal down. No noise after let off.
 
Acceleration from a stop transmission makes one hard clunk with the first to second gear down shift and then normal driving after that. And it's only when you accelerate hard. I'd do all of the above stated if it hasn't been done and see how it operates after that.
 
Just a note to those inquiring, it would help TONS if any audio/video can accompany the description of noises made, I know one guy on another forum had complained that when he started truck it would make a "clang with a constant knock that changed with rpm, he posted up short vid & within 15 sec. of play it was clear he was about to have a rod come thru the block, point is there's no substitute for being there & next best thing is audio/visual help...
 
I have an 08' doing the same this as well. I only notice it under hard acceleration. If I just drive casual I don't notice it. I dig what you are saying about the video, However I would describe it as a clicking sound. Reminds me of lthe sound an electric spark makes when you short out a wire in the house only louder. It is definitely coming from underneath the vehicle and not the engine.
 
Drop the driveshaft and manually check the U joints thru their range of movement for roughness. A little play in the front joint + a little play in the rear joint stacks up fast. Another thing you can look for is orange rust streaks on the U joint where the cups and cross join. This shows rusty and failed needle bearings. U joints have a life span, and 75 K is a decent amount of life. Greasing the slip joint while you have the shaft down.

You can test the joints for radial play by putting your parking brake on and leaving your trans in neutral. Put the thin end of a pry bar in each joint and rotate it left and right. This will show you any play in the U joint assembly. Do this for both joints.
 
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