Hi to all,
Have an 04.5 crew cab duramax with allison with 13000 km on it. At idle in gear it has recently developed a strong vibration which can be felt through the steering wheel,dash. and brake pedal. This is extremely annoying ,the dealer is at a loss and TAC has not been of much help. Recent history includes a power steering pump replacement for lack of power assist. This replacement caused a severe brake pedal vibration which was fixed by securing the pressure hose to a bracket bolted to the master cylinder. The dealer feels the vibration in it now is related to engine transmission harmonics. Other than this it runs great.Injectors are fine (lly) and mounts visually look o.k.As sonn as rpm is brought up vibration dissapears. Vibration is worse cold than hot is the only other thing. Any ideas and all the best for 05.
laker, BC Canada

Can you hear it, or just feel it?

Hi
I feel the vibration as i described but cannot really hear it, however if I am out of the vehicle I can hear what I can only describe as a light singing noise coming from the engine compartment. This noise seems to be most loud on the bottom area of the engine oil pan.I do ot know if this is normal,Dealer called it turbo resonance.
I dont think the two are connected but to eliminate the pump and hydroboost unit I will take the serp. belt off and run it. If it is still there then it is either engine or transmission related.I have also noticed my tailpipe as quite a bit of vibration at idle which goes away when rpm is increased.Will be talking to the dealer again tommorrow.I believe that socal had a similar problem as I did a search on this would like to hear what happened with that.
Thanks Max
Laker

That is a good idea to take off the belt. if it started after a P/S pump replacement, then you know what to look for... anything touched during the P/S pump replacement. Make sure some meathead didn't try to hammer the pulley back on or something.

Took of the belt and noticed no difference in the vibration,It can also be felt in the dash controls, dash pad ect. Feeling the engine air intake hoses you van feel a significant amount of vibration but am not sure if it is normal. Am also starting to wonder about the harmonic balancer or an engine mount problem.

This is not going to be a quick fix.............
Thanks Max,
Laker

You might check this... http://dieselplace.com/forum/showthread.php?t=17496&highlight=firewall...But also anything else that may be touching the firewall that shouldn't.

I know what you mean (laker) and my 2004 has a harmonic vibration..it goes away when it reaches full operating temp.,,,up till now i have not seen a diesel that does not produce a harmonic vibration. I have driving 3406 cats that will turn nuts in our mirrors from harmonic vibros.if its got harmonic IT A TRUE DIESEL>>>

I have heard of the key in the harmonic balancer shearing, allowing the balancer to move on the crank. Might have the dealer check that.

Just to update this thread......Truck at dealer they have diagnosed the vibration as being first order engine based.They feel it is a ground out condition but are concerned enough that a DMAX engineer is involved. Will see.......

I was just wondering if they have found anything wrong yet? Mine is the exact same, with the vibration/buzzing getting really bad the colder it is. When it was around zero for a week last month, various dash and door panels would buzz at idle. Now I just take my hands off the wheel whenever I'm stopped to deal with it. When it warmed up outside to the mid-forties for a couple of days it was almost like a different truck since it was pretty smooth. I tested a truck off the lot at the second dealer to look at the problem and it was exactly like mine, so I think I'm outta luck!

Are they supposed to vibrate/buzz like crazy when its cold out?

truck is being driven by DSM tommorrow. I and the dealer Feel the mounts may be to hard and transmit an excessive amount of engine vibration to the chassis when cold. When it warms up mounts are slightly softer and vibration is absorbed by mounts before it reaches the frame. Will keep all posted.
laker

Isuzu engineer now involved.Laker

Thanks for the update! On another forum (I'm not sure if I violate any rules by saying which one) another person is having the exact same problem with his truck. Thanks for your work on this!

Engineer feels mounts are to hard. They are going to replace my engine mounts and see what happens.
Laker

Hello,

I was wondering if they made any progress on your truck? Also, I sent you a PM to see if I could get some more information to provide the dealer when I make another service appointment. I'd appreciate any help you can provide.

Thanks!

Hi,

Still waiting for dealer to get Mounts in. The temps here have warmed up considerably and this has improved the problem some what. Do us a favour and tell me how much your front bumper vibrates this is also tied into the vibration concern.I have a feeling this will not be a painless fix......
Thanks Laker.:cool:

Not that this is your problem, but I had a brand new Impala in the other day with a first order engine vibration, turned out to be 5 quarts overfull of oil. Sometimes it is the simplest things.
Laker, have they used the EVA tool on your truck? What were the Hz readings? I have some software that puts these numbers to good use, if you have them...

Hello,

The other day it got to 60(F) degrees here, and it was like I was driving a different truck. The steering wheel still buzzed, but the brake pedal was 80% better. If it ran like that all the time I'd be a happy camper. It still buzzed alot until the truck had been running for about 30 minutes, then smoothed out. Could this be the motor mounts heating up from the block and softening? In the cold weather(40 degrees or less) though it never gets better even if its been running for an hour. Its back to the upper 20s now and its back to buzzing again...

Regarding the bumper...If you have ever placed your hand on the top of the engine (the air intake resonator thing) and feel the way it vibrates, my front bumper is almost the same only a little less than that. The GM factory nerf bars also vibrate, but to a much lesser degree. Its felt in most parts of the truck to varying degrees. Below 10 degrees is when the seats start buzzing and I really hate my truck then.

Thanks for your help on this!

Hi to all,

Yes they have used an EVA machine on my truck and in their words engine vibration is not the problem as it is the same as compared to other new vehicles.What is different is how this engine vibration is being trans ferred to the frame unlike the other vehicles they have used to compare to mine.
The plot thickens........
Thansk Laker

Truck went in today for engine mounts and exhaust weights.

Later, Laker.

I.....can't.......take........it.........any...... ....more............................Please, please, please let us know what's going on with the new mounts and weights!

Thanks!

Craig

Spoke to foreman today,New mounts have gone in .They found problems with the way the old mounts were installed resulting in a ground out condition. they have a baseline with the eva machine and are going to cold soak the vehicle tonight and do a comparison.I will be asking to see the old mounts.I am sceptical as to the fix but time will tell Or should I say a day or two. Will update this as soon as further info comes to light.

Laker

Laker,

How about an update - did the fix work??