Jaybug

Since I've had this truck I have always heard this noise and have been curious about it. It's a sound in addition to the usual engine sound. The best way I can describe it is it sounds like a chain dragging on pavement. It happens when the RPMs are low in any gear, including reverse. It always has the same tone. It doesn't cycle up or down or change pitch. It remains constant when it's present. Usually I hear it when decelerating toward a stop, or am taking off slowly. Thoughts?

KRB

Have you checked to make sure you don't have a chain dragging on the pavement?

Seriously though. You are saying it is constant - doesn't change with rpm OR vehicle speed? Braking? Gear?

BHD

Could be about a hundred things. Check your u-joints, or pull the drums off the back and make sure none of the springs are broken and rattling around inside.

On a side note, as a joke, we used to tie pop cans to the underside of co-workers cars, no noise til they slowed down. Or we would put some gravel inside hubcaps. Just FYI

KRB

Gravel in a hub cap was what I was thinking but by his description it sounds like maybe the sound is constant whether the vehicle is moving or not and regardless of rpms?

mknittle

maybe something like a heat shield or internal muffler part vibrating.

KRB

Now you may be on to something!

gyman98

Could just be clutch noise too

BHD

Muffler bearings going bad?

mknittle

I think it is the heat

Jim5870

Front rotor dust shields touching the rotor?

mknittle

I can see that making that sort of sound.

u2slow

Is it this noise?


I haven't figured it out yet...

Jim Lane

Is your tappet cover sound absorbing cover missing?

Probably some sheetmetal vibrating from the engine's rattle.

Do you have a 4" downpipe, the connection to your exhaust is a rattle point.

Manual or auto transmission?

I have an odd sound coming from my exhaust that I think started once I bumped my timing.

Jaybug

KRB- From the cab it sounds constant. The sound is present at low RPMs. Once RPMs go past a certain threshold then the sound is absent. I don't have a tach but if I were to dBrakes seem to be unrelated.

BHD- I've had gravel in a hubcap before, know the sound very well, and I assure you it isn't that.

Mark- Perhaps it could be the heat shield or muffler part but I'm doubtful. My old '94 Suburban with the 6.5 detroit diesel used to have a muffler vibration that occurred for a minute or so during a cold startup. I know this is a completely different animal but it sounds nothing like that. The exhaust vibration was a much deeper tone.

gyman98- I doubt that it's clutch noise because I notice that if I'm parked and in neutral and put just the slightest pressure on the accellerator pedal then I hear the infamous noise.

Jim- It's a manual trans. Stock exhaust. I don't hear the noise coming from the tappet cover. I've never removed it so I can't say what's present or missing underneath.

u2slow- By golly that sound in the video as soon as the oil cap is removed SURE does sound like it. I popped the hood on my truck and did the same thing. Unlike in the video my engine and fan noise drowned out most of the sound but if I got my ear closer to the oil fill port I could hear it pretty well. I think you nailed it.

bigragu

U2- check the end play on your crank shaft with a dial indicator set up at the front. I believe cummins spec, is not to exceed .012". Mine made all kinds of rattle, which I thought was normal. Did all the preventive stuff like valve adjustments, etc. didn't help, so I thought the noise was the norm. Then it got worse, and actually showed full force by the bell housing. Did the dial indicator thing and had .045" end play! Turned out my crank shaft thrust bearing shattered on me. After the repairs, the truck sounds so different now. Much quieter. Sounds like everything is tight.
If, it does turn out to have excessive end play, feel free to PM me, as this fix is still fresh in my head. Plan on doing upgrades by swapping out the old crank and rod bearings while your in there. Only thing I wished I had done different was learn about Clevite bearings, vs. the Cummins ones I used.
Bottom line, let's hope it's not that, cause it's a job.