High pressure fuel rail sound dampining????

[greyjimmy]

Thank you Justin.  Other than that and the funky upshifting I see others complain about,  the truck is a Cadillac. Super smooth.

[Justin101714]

I’ve found that most of the 8 speed concerns I have that programming or clutch learning doesn’t fix is actually in the valve body itself, I’ve disassembled quite a few that have had some sticking valves or some that just feel gritty in the valve bore. As of now, the valves are not repairable and the whole assembly is replaced.


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[madsen203]

Found a fix for this. It's been months since I brought it home. It has been since day one after a few hundred miles that this noise has been there. Finally climbed under the truck to look. Then I lifted the carpet. 

 

I found there is a wire (not sure yet what it goes to) that enters from under the carpet below the left rug mount towards the seat. I first moved the wire so it was routed differently because it was causing a lump under the mat that was uncomfortable. I then put a piece of DynaMat over this to seal the grommet and wrapped the wire so there was no "air gap" to allow sound to penetrate. 

 

The sound has dropped dramatically. It is still very faint. I found the ticking is from the DI or valve train that reverberates down under the truck past the transmission/transfer case. The sound would then come through this grommet and enter the cabin. Now that there is dynamat over this, the sound is no longer as loud (hardly notable). I only had a tiny piece of dynamat so I will order a few square feet of off-brand to put a few layers on top and one under the truck. That should eliminate ALL of the ticking sounds. 

 

I am stoked! The truck finally feels "new" again. 

[Bwoodkid]

On ‎3‎/‎31‎/‎2018 at 4:47 PM, greyjimmy said:

I just bought a 2015 Sierra 4x4 with the 5.3 and 60,000 miles.

At idle it sounds like an industrial sewing machine under the hood.  Sometimes a light knocking as if coming from a lifter but I just had full diagnostic done by a third party and it showed nothing. They acted as if it was not an issue.  It only does it after its warmed up and at idle.  It's quiet otherwise.   Is this typical?

my 15 5.3 40Kmiles ticks at cold start then goes away after warm up.  Just had the left bank lifters replaced and the noise is satill there,  there saying its the high pressure fuel pump and its normal. WTF

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