Rattle when slowing down

kinzerhaus3 · February 14, 2020

Got a puzzling one here. 2018 Silverado Eassist 8 speed auto that I have had numerous weird issues with since day 1. The latest is what sounds like a nut or socket rolling in the bed when you Slow down. The bed is clean. After much trial and error I can finally get it to duplicate reliably.

Get speed up past 40 -45

Slow down with extremely light pressure on the brake pedal.

At 27mph when the transmission downshifts you hear the rattle that sounds like a nut rolling about 6 inches in the bed

You do not hear the noise on acceleration

Too hard on the brake - noise is very soft

Slam on the brakes - no noise

Coast to a stop- no noise

Pushing down on the brake pedal what feels like 1/4" - noise is loud

Things they have done to the truck:

Changed transmission fluid and updated software multiple times over the first 30000 miles to fix harsh shifts

Replaced the valve body in the transmission about 5000 miles ago due to extremely harsh shifts. So harsh it rattled all the screws loose in the overhead bin and it fell out of the ceiling.

Dealer discovered there was extremely low fluid in the rear end about 2000 miles ago. Said it leaked out and I must tow a lot (I don't tow anything) LOL. Issue had been my main complaint from day 1. Symptoms were a shudder in reverse at low speed. 100 miles left on the warranty when they finally figured this out.

Noticed the rattling noise after they replaced the fluid and honestly though they left a socket on the spare or in the frame.

Took it back in 1000 miles later as the reverse shudder was still there and reported the noise. Diagnosis was noisy leaf springs we will grease the fronts

Dealer replaced the rear end center section since it still had the reverse shudder. (Of course it was bad it had low fluid from day 1 and it now has 37000 miles on it)

Still has the same rattling noise and now I can make it happen at will

Just finished reading another post here and they mentioned trash in the valve body. So I am going to try to make the noise happen with the truck in neutral and will update later

Any ideas?

Thanks!!

kinzerhaus3 · February 18, 2020

Have tried several times to duplicate the rattle when the truck is slowing down with the transmission in neutral. It does not rattle when the transmission is in neutral only when the truck is in gear

kinzerhaus3 · March 4, 2020

Dropped the truck off a week ago. The dealer called to tell me it was the transmission, but they dont know exactly what yet. Tech that rode with me when I duplicated the noise multiple times told me it was transmission and yet it took them a week to let me know the same thing. Not sure they have a clue or are they stalling because they are working on other stuff.

ThaBoss · March 29

Sorry to revive an old thread, but what ended up being the issue? My 2016 with e-assist is doing the exact same thing and the dealer hasn't been able to figure it out for 2 months now.

Croffocc · April 30

I was looking to see if there are any updates as well. I have a 2017 eassist that is doing the same thing. Light brake and rattles between 25-30 mph.

GMCustomerService · April 30

15 hours ago, Croffocc said:

I was looking to see if there are any updates as well. I have a 2017 eassist that is doing the same thing. Light brake and rattles between 25-30 mph.

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