Jump to content

Engine knock a 500 miles

bass mechanic
 Share

Recommended Posts

Clint GEFFERS New Member

Clint GEFFERS

Posted
Posted
On 10/18/2019 at 7:13 PM, bass mechanic said:

 

Have any of you head a faint low frequency engine knock at idle from under the truck?

Seems like it doesn’t happen all the time but occasionally after it’s been driven and I start it up again.

 

 

Sent from my iPhone using Tapatalk

 

Yes since day one and it gets louder as the engine reaches operating temperature. Had dealership work with GM and after a week they said it's normal. They gave me the ticking printout. I even had the truck put on their computer. I had them pull other new 2020s. The other new trucks did it also. I am stumped!!!

  • Replies 135
  • Created
  • Last Reply

Top Posters In This Topic

Popular Days

Top Posters In This Topic

Popular Days

Popular Posts

bass mechanic
bass mechanic

heres a video with the sounds  

Sask Farmboy
Sask Farmboy

My first chime in for this topic. My 2020 Denali DRW is being built in 2 weeks so I will be checking it out closely. I used to be a Chevy tech and finding stuff like this was my life. I

MN6.2
MN6.2

Didn't they have to change the back of the engine to accommodate the new 10 speed transmission? Doesn't seem like enough to create a knock like that but that is one major thing they changed. 

Posted Images

newdude Senior Enthusiast

newdude

Posted
Posted (edited)

Heads up diesel knocking folks:   

 

Quote

 

#PIP5711: 2020 6.6 L5P Duramax Warm Engine Idle Knock Noise - (Mar 3, 2020)

 

Condition: Customers may have a concern of a thumping or knocking noise coming from what sounds like the rear of the engine.

 

Cause: Characteristic noise being amplified by the transmission bell housing.

 

Correction

The noise described in this communication is audible in the interior and exterior of the vehicle but is more pronounced in the interior.

The noise is easiest to duplicate under the following conditions:

Engine at idle (about 600 RPM)

Engine oil temperature 113 - 185 degrees Fahrenheit (45 - 85 degrees Celsius) 

Transmission in P/N

HVAC fan off

Radio off

 

To verify this is the noise described in this PI, remove the accessory drive auxiliary belt.  If the noise level is significantly reduced it should be considered characteristic of the 2020 MY truck and no further repair attempts should be made.

 

Engineering has provided the following procedure for belt removal, testing and installation:

  1. Remove the air cleaner housing.
  2. Remove intake air duct.
  3. Separate the charge air cooler (CAC) tube and position aside.
  4. Remove belt and position aside.
  5. Install CAC tube.
  6. Loosely place air box and intake duct back in place. (So you don’t set a code for sensor when starting.)
  7. Start engine and verify noise is gone.
  8. Remove loosely installed air box and intake duct.
  9. Separate CAC tube.
  10. Install belt.
  11. Install CAC tube.
  12. Install air box and duct.
  13.  

Note: Do not run the vehicle more than three minutes without the auxiliary belt installed. Do not raise the RPM higher than idle with the belt removed.

This noise has no short or long term effects on the engine. Do not attempt repairs for this noise.

 

The short of it is...take it in, have them pull the belt.  Have them run it with you present if possible when the belt is off.  

 

Edited by newdude
crosslakejohn New Member

crosslakejohn

Posted
Posted
7 hours ago, Capt.Wackencracker said:

That's the exact location I picked up the noise with my stethoscope! 

Don't see any drive belts nearby.

yeah but that GM document on belts/pulleys might help someone, so I posted it. It's not as if GM is on these forums providing concrete course of action for owners with noisy trucks or even basic info.

That photo displays the source of the thump at idle on my new truck.

I had to check twice, but you are correct!!! No belts nearby.

Tomato Enthusiast

Tomato

Posted
Posted

I wish they had a section regarding: "If the noise does not stop..."  Has anyone done this at home or at the dealer to check it?

Sask Farmboy Enthusiast

Sask Farmboy

Posted
Posted

My first chime in for this topic.

My 2020 Denali DRW is being built in 2 weeks so I will be checking it out closely.

I used to be a Chevy tech and finding stuff like this was my life.

I'll get my stethoscope out & will be all over this engine like a monkey on a muffin if there are any noises.

If you guys can let me know what the oil pressures are that you have been seeing at different temps and RPM's, that would also be a help because I'm curious to hear that the noise was less after the new oil pump was installed.

Also state whether the oil pres reading is from the dash gage, dash digital readout, scan tool or a master gage installed into the oil gallery somewhere.

There is always an explanation when something is different than it has been before.

  • Like 2
ArtK New Member

ArtK

Posted
Posted

I just picked up a Denali built in mid February and it is making the same noise.  To me it does sound like it is coming from the fan clutch.  I hope there is going to be a fix soon, definitely very annoying.

Joe mash New Member

Joe mash

Posted
Posted

I just purchased my new 2020 duramax. With 600 miles on it. it now has a loud thumping noice at an idle after it warms up. I have owned a view never had this noise. Any suggestions?

  • 3 weeks later...
20L8TSierra24 Senior Enthusiast

20L8TSierra24

Posted
Posted (edited)

Man, I've had the itch for a new High Country lately but I'll wait and see what happens with this knocking. I couldn't live with that noise! It would drive me crazy!

Edited by 20Bowtie14
Colossus Senior Enthusiast

Colossus

Posted
Posted (edited)

Hey it's no big deal unless it gets worse over time.  Many of us old timers on this site remember and lived with the cold start knock and piston slap that was very evident on the 99+ 5.3L & 4.8L engines.  Most of those engines ended up serving us just fine with no long term effects. 

Edited by Colossus

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Latest Articles

  • Posts

    • KARNUT
      OCI, not when but why?

      By KARNUT · Posted

      Well if you insist.
    • diyer2
      OCI, not when but why?

      By diyer2 · Posted

      You have to have the last word. 
    • Chuck FB
      summer road trips in the 2026 2500HD

      By Chuck FB · Posted

      I am sure that was quite the pass experience and not a great place to experience during the winter when the conditions are not good. I've seen video of that pass and also more detailed information and pictures about the wrecks at that one hair pin turn where tractor trailers have flown right off the cliff and I am sure from all the warning signs that you know the exact curve that was !. After all there is a reason why a song was made about Wolf Creek Pass !. By the way and I didn't realize this either when I bought my truck as its nothing I even thought of that would be programmed into the cruise control and this occurs in either the basic or the more advanced cruise that controls your distance behind a vehicle and that is the brakes going down a hill are being applied as soon as the vehicle goes a certain speed over the set cruise speed. While it certainly does force downshifts in the transmission as you found out with cruise on while going down hill, its also dragging the brakes as needed to keep the speed controlled to what the cruise was set to. For me, I find that unsettling simply because I have no concept then as to how MUCH brake input is being used a and just how hot are those brakes getting and the wear factor as well. I can see that system getting a person into trouble on long mountain grades while pulling a trailer as it would not only be standing on the brakes of the pickup without any driver input, it would also be automatically applying the trailer brakes and it could cause a run away unit by overheating the brakes. Its one thing on a shorter hill and if the driver allows it to do its thing but on a long mountain grade is where things could get so out of hand. As someone a while back on this forum said, they had someone following them at night I believe on a down grade and had the cruise set and the person behind them could see the brake lights being energized all the way down the hill. I figured when I saw your comment that you didn't know and would have no way of knowing that your truck was applying the brakes and that you would and rightfully so assume you only used the brakes when you pressed on the pedal to slow down more than the cruise set speed for the slower sharp curves. So its good knowledge to know this about the newer GM trucks, certainly when doing any descending on long mountain grades. In the future try kicking off the cruise and use the the manual mode on a pass to see what that is like as I know myself when I first experienced it I thought no way can this engine be holding me back this well and tried the same hill in manual mode and sure enough the engine was revving way up and still could not hold the trucks speed down like it could in cruise mode.    Fuel mileage, that is where a really low sleek type of car can do better at higher speeds, certainly it starts sucking fuel too but a tall pickup is pushing massive amounts of air and also allowing a lot more air under it and the tow mirrors as in elephant ears pushing through the wind  as well. Driving like grandpa is about as good as one can do when driving one of these if trying to get the best fuel economy they can. I bet these trucks would get the best mileage they can if driven on a freeway in Florida if not busy traffic at a sedate speed and that sea level elevation without hills, vastly different then Colorado !. 
    • KARNUT
      OCI, not when but why?

      By KARNUT · Posted

      It’s over for almost 24 hours. Are you playing Eddie Haskell? 
    • diyer2
      OCI, not when but why?

      By diyer2 · Posted

      Again, really you two.

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...