Heavy knocking sound. Video included

[DcDuqueMuerto]

Hey All,

Putzing around with the truck (m923a2), my cousin mentioned the engine sounds like it's knocking. Now, it has sounded that way from the day I brought it home from the base. It has driven a few thousand miles, and passed emissions during that time. Never had any issues with it engine wise. I even asked the guys at the local Cummins dealer if it sounded bad, and they didn't seem too concerned.

I can't tell from videos, and not sure if I'm being paranoid. But, it definitely sounds bad to me.

I couldn't get the video to post here, so hopefully the link is ok:

https://youtu.be/k5XuXulvltU

Any thoughts/suggestions?

 

[M35A2-AZ]

Sounds like the idle is a little high, not sure if it has a bad knock or not.

 

[DcDuqueMuerto]

I had the choke way up

 

[DcDuqueMuerto]

I posted this in the wrong forum. Trying to delete the other.

Hey All,

Putzing around with the truck (m923a2), my cousin mentioned the engine sounds like it's knocking. Now, it has sounded that way from the day I brought it home from the base. It has driven a few thousand miles, and passed emissions during that time. Never had any issues with it engine wise. I even asked the guys at the local Cummins dealer if it sounded bad, and they didn't seem too concerned.

I can't tell from videos, and not sure if I'm being paranoid. But, it definitely sounds bad to me.

I couldn't get the video to post here, so hopefully the link is ok:

https://youtu.be/k5XuXulvltU

Any thoughts/suggestions?

 

[adamsoffroadperformance]

sounds like you have an airleak and the knock sounds like the air compressor when the unloader valves are bout to pop. sounds normal to me

 

[SETOYOTA]

Did you have the throttle pulled out? If that's idle it sounds high to me.

 

[74M35A2]

I had the choke way up

Awesome

 

[SETOYOTA]

I had the choke way up

Diesels do not have a choke.

 

[ghettoct]

mine had same sound, was the air compressor. it was leaking at the head and the unloader on top of compressor. just mix up some dawn and water and squirt it on the compressor top and watch for bubbles. i replaced my compressor through napa and the knock is gone. as well as air leak.

 

[tbar123]

Do you only hear it from the front of the truck? If so it's not the engine it has something to do with the radiator mount. I picked up the same knock after I rebuilt the radiator.It's from a bolt not being spec'd out. Most likely the mount!When the fan turns on it disappears.

 

[DcDuqueMuerto]

I'm aware, it was a mistype. Trying to multi task didn't work out too well when I posted this originally.

Yes, the throttle was pulled out.

 

[Floridianson]

I'm aware, it was a mistype. Trying to multi task didn't work out too well when I posted this originally.

Yes, the throttle was pulled out.

I do that all the time plus ADHD does not help as the mind is somewhere else when typing.

 

[mcmullag]

Would you be able to re-post a video/audio of when it is all air-ed up and the compressor has stopped running?
(if I remember correctly, after you get that loud hiss from the bottom of the air dryer, the air compressor kicks off)
I do remember a knocking noise on my two, when the air compressor was running.

 

[DcDuqueMuerto]

I can do that. There was a leak from the top of the compressor. We fixed that (or thought so) as we replaced the gasket at the top.

Hoping not to have to replace the compressor, but we'll see. I'll get a video posted this weekend.

 

[Stranger]

I was being driven crazy by a heavy knocking sound at the front of mine.

Turned out to be a loose tow shackle vibrating back a forth on the mount. A quick squeeze in the vice fixed it.

 

[infidel got me]

Sounds like the hammers in the compressor need new handles.

 

[DcDuqueMuerto]

The compressor was/is on it's way to the grave. Had to take it in for emissions and the shop did some inspecting and verified it was toast. It'll hold air, just won't build it up. Putting in a new one this weekend.

 

[dmetalmiki]

Awesome

Was that the fast idle device or screw you refer to as the 'choke', as diesel engines do not have a choke.

 

[DcDuqueMuerto]

Was that the fast idle device or screw you refer to as the 'choke', as diesel engines do not have a choke.

Maybe Brexit has gotten to you...

Try reading the other posts....I acknowledged it was the idle as I was doing two things at once when posting on the forum and mistyped.