Engine/Transmission (1998.5 - 2002) low rpm engine vibration

[Markan]

I have a low rpm/ low frequency engine vibration (idle to about 1k rpm) Noticed it a couple of days ago, It seems to have come on suddenly. I can feel the vibration in the truck body and the engine as well as hear it. No part of the exhaust system seems to be touching anything. I have checked the harmonic ballancer, the rubber looks fine, the alignment marks are lined up and I don't see any wobble. I looked at the engine mounts and they look ok to me. I bought the truck new, it is totally stock with 137K "easy" miles. No MIL, no codes. Any Ideas?
Thanks,
Mark

 

[klcammie]

When checking the harmonic balancer where you able to see back side[engine side]. When I first checked mine it didn't look to bad. After reading about Fluid damper I bought one. After removing my old one and looking a the back side I was very glad to be changing mine. It was missing pieces 1 to 2 inches long and bulging out. I couldn't see this while mounted to truck.

 

[DFerverda]

Maybe a u joint? Have you changed your rear end gear lube, I didn't put in friction modifier the first time i changed it and it would "growl" when i took off and turned.
Carrier bearing, rear transmission mount. Sometimes the problems are hard to find till something comes apart.
Dirk

 

[JR]

Is this vibration with the truck sitting idle or in motion?

Have you checked your flywheel through the inspection cover?

 

[Markan]

I was able to see small portion of the back side at a time & by turning the engine I was able to see it. it looked ok to me. The rubber on the front side sticks out about .040". I'm not sure if that is normal or not.

 

[Markan]

Vibration is present when truck is moving or parked. The vibration is there all the time but seems most noticeable around 900 rpm. I have not removed the inspection cover, I'll do that.

 

[MTstones]

Did you ever figure out what was causing the vibration? My 06 seams to be vibrating more recently and I'm trying to figure out what all to check.
Thanks,
MarkL

 

[Markan]

I have not yet figured it out. I took it to Source Automotive in Clackamas Oregon (I live in the Portland area). Rip wasn't sure what is causing the vibration, he suggested I could replace the injectors and injector pump or just keep driving it and see what happens. I'm still driving it a year later. I'm now at 146K miles, I've put about 9K miles on it in the last year.
Mark A.

 

[KATOOM]

Is the vibration just barely noticeable or is it so bad that you can visually see things shaking in the cab?

 

[Joe Mc]

I've heard of the flex-plate cracking where the TQ converter bolts to it, but note on a stocker with so little miles. I've got 216 on mine and it hasn't been stock since about 120k. However, I did install a Fluidampner about 60k miles ago and noticed it idled much smoother, ran me $425 or so from Summit. Here's what I found for an 01 Cummins https://www.summitracing.com/search...ngine-family/cummins-diesel-inline-6-cylinder Apparently the Tack is driven from the balancer??? Anyway there's 5 items listed, one with sensor relocation kit included $490, three others (one's for a 12 valve, odd that it would show up when I specified year of "01", Summit...) and just the sensor relo kit. Check out your flex-plate - as much that you can see of it anyway with the inspection cover removed, unlikely that's the problem, but good to check anyway.