LBZ: 2006 Eng Vibration between 1200 to 1500 RPM

[Macon Rounds]

The problem shadows itself like a tire imbalance issue, however i just recently discover that the vibration is NOT a tire issue or MPH related.
"THE PROBLEM IS rpm RELATED" and most prevelant at 1200 to 1500 RPM's . While selected to PARK or Neutral position and slowly reving the engine thru the RPM range a slight vibration is noticed however between the RPM range of 1200 to 1500 RPMs it is obviously not normal. The vibration is similar to the feeling of a tire out of balance.

I have edge juice programmer and changing performace setting has no effect on the issue. An Allison Transmision specialest said it does not seem like a transmission issue. The light truck dept. at our chevy dealer also did not have any idea what it could be.
The truck has 140,000 miles and has had regular service. I have owned the truck since 50,000 miles and the vibration issue has progressively depeloped over the last 20,000 miles. I have ocationlly used the truck to haul loads with combine gross viehicle weights of 25,500 LBs. Any Technical help would be greatly appreciated.
PS. it is NOT MPH "miles per hour" related !!!
Thanks in advance.

 

[PACougar]

Could be a cracked flexplate, since it happens without the truck moving it's clearly not drivetrain related. Might even be a bad injector. Have you scanned the engine for codes?

 

[LBZ]

Cracked flexplate would be my guess.

 

[Macon Rounds]

Cracked flex plate has been mentioned but Tranny guy said its not likely. injector balance good. Flywheel a posibility but not a typical duramax problem. But then again this is not a normal issue. Thanks for the feedback.

 

[PACougar]

Cracked flexplate is more common than you think.

 

[Stingpuller]

Shake

Has it had a water pump put on recently? I have seen the balancer bolt not getting tightened enough and it will spin the balancer. You might want to pull the balancer and check the pin in the crank.

 

[Macon Rounds]

Original water pump..
Balancer was my thought too and will be checking that out this weekend.
Flex plate most probable cause. But big $$$ to pull the tranny just to check it out, so we are eliminating all less expensive possibilities first.

 

[Macon Rounds]

AllData shows tool J44643 for harmonic Balancer removal however this is just a holding too to keep th crank from turning. Anyone know what type puller is need to remove the balancer from the crankshaft ?
Thanks in advance

 

[Akers]

How bad of a vibration are we talking here? Could you set a glass of water on the dash and it'd knock it over or not quite that bad?

I try to think horses when I hear hoof beats not zebras if you get what I'm saying. If the vibration is little more than annoying and not shaking the whole cab I'd check the exhaust system. Look for broken mounts and such. Worth a shot anyways.

 

[Macon Rounds]

Level of vibration ??? Vibration is not so much that you would consider it harmful to "components" but enough of an anyoyance that even the wife knows something is wrong with it. Remember vibration is present while in Park or Neutral, and also in all gears while moving. And most noticable at 1200 to 1500 RPM.
Gotta set of mounts at the house ready for installation. Dont figure its that but gonna change them as a precation.
Exhaust ? well, nothing is loose on it.

 

[Hot COCOAL]

Have you looked at your engine mounts?
Maybe one is torn or somehow became loose?
Just an idea...

 

[TheBac]

AllData shows tool J44643 for harmonic Balancer removal however this is just a holding too to keep th crank from turning. Anyone know what type puller is need to remove the balancer from the crankshaft ?
Thanks in advance

36mm socket and a big-ass breaker bar. Balancer should slide off. It is not pressed on.

 

[Hot COCOAL]

36mm socket and a big-ass breaker bar. Balancer should slide off. It is not pressed on.

Don't mess around with a 1/2" breaker bar either...
I broke mine trying, then I got a 3/4" breaker and a 3/4" to 1/2" impact rated reducer cuz I couldn't locate a 36mm 3/4" drive socket and wound up twisting it!

So to save some headache I'd suggest using a 3/4" bar on a 3/4" socket from the get go...
:thumb:

FYI, the crank balancer bolt is torqued down to something like 278ft lbs, and feels like it breaks free at like 400ft lbs
Lol

 

[OregonDMAX]

Don't mess around with a 1/2" breaker bar either...
I broke mine trying, then I got a 3/4" breaker and a 3/4" to 1/2" impact rated reducer cuz I couldn't locate a 36mm 3/4" drive socket and wound up twisting it!

So to save some headache I'd suggest using a 3/4" bar on a 3/4" socket from the get go...
:thumb:

FYI, the crank balancer bolt is torqued down to something like 278ft lbs, and feels like it breaks free at like 400ft lbs
Lol

Or buy higher quality tools :thumb:

 

[TheBac]

Or buy higher quality tools :thumb:

Honestly, a cheap AutoZone 3/4" breaker bar worked just fine.

 

[OregonDMAX]

Honestly, a cheap AutoZone 3/4" breaker bar worked just fine.

Yeah im sure it would, but if you break a 1\2" breaker bar doing a dmax water pump job then that tells you it wasn't very high quality.

I don't own any 3/4" tools and I have never needed them on a dmax.

 

[Macon Rounds]

Thanks

 

[Macon Rounds]

36mm

 

[Macon Rounds]

Looks like ill be picking up a 36mm socket and a 3/4 drive breaker bar... Thanks

 

[onebaddmaxxx]

Ummm I have a 1/2" Matco and snap on breaker bars that are 4ft long...... The snap on broke the 1/2" head off the Marco broke the whole head and it slammed thru my radiator. I'm with tom, 3/4 and never look back