Engine Vibration

[Gibbs]

My 04. 5 4x4 auto QCSB that I've only had for about 1000 miles had a very noticeable vibration while in OD at almost any speed. When I got it, the front wheel joints were shot, so I replaced them and it didn't make a difference. Then I removed the front driveshaft to see if it was causing vibration and that didn't change anything. But I went ahead and disassembled it and regreased everything, including the CV ball and the slip splines. Next, I installed my Centramatic wheel balancers that were on my old truck and that didn't help anything. Yesterday I went ahead and replaced both rear driveshaft u-joints and also removed the OEM harmonic damper from the slip yoke since the rubber was starting to look questionable. This also made NO difference.



Today I had my friend drive it and he could also feel the vibration. Well he pulled off on a side road and stopped, put it in neutral, and slowly revved up the engine. At around 2000 RPM, there is very noticable harmonics/vibration that doesn't seem right. We checked his truck and its very smooth when revved up. Injectors crossed our minds, but the truck starts very quickly (usually a 2 count) and runs great with plenty of power. When I got home, I closely inspected the Engine damper with a flashlight and mirror and the rubber is still intact and looks pretty good for 144,000 miles. The truck idles smoothly, but when brought up to around 2K, it definitely has something going on. We were thinking that maybe under load, the vibration could be felt at an even lower RPM, thus being able to feel it when it hits OD at around 50 MPH and the 1500-1600 RPM range.



The damper bolts are tight, the damper looks good, I've torqued the torque converter to flexplate bolts (some were a little loose), the fan hub bearing and fan clutch don't have any play I can feel (with the belt on), and I don't see anything out of the ordinary. Next, I'm going to look at the motor mounts a little closer to see if there's anything loose or damaged.



Any other suggestions? Could the flexplate or torque converter be a possibility? What about any engine internals? Turbo?... . Like I said earlier, the truck runs and drives great, and besides this extremely annoying vibration, everything SEEMS to be great. I've been wanting to do the 6. 7L damper but it may just mask a more serious problem. Any input would be appreciated. It just drives me nuts and I don't want a more serious problem to rear its ugly head later on down the road.

 

[Prairie Dog]

CV ball and slip splines? On a 2500?

 

[Gibbs]

The ball is in the front driveshaft CV assy. The "slip splines" accommodate axle movement via splines that slip in and out.

 

[Prairie Dog]

Interesting, I've never seen a HD Dodge truck with CV joints up front. Always just a "Live axle".
Truth is, if you have a HD Dodge Cummins you don't have a ball or anything like a CV, you have simple u-joints.

 

[Gibbs]

Wow, do I really have to explain this?? Look at your front DRIVEshaft. I never said anything about AXLEshaft. Those are 2 different components. The double cardan joint in your front DRIVEshaft is known as a CV. That's the best I can explain it.

 

[Prairie Dog]

Sorry I miss-read your post, I meant no offense. I've just never heard of a u-joint being referred to as a constant velocity joint.

This is a typical CV joint:
#ad


This is a double cardin joint, which as you know has two u-joints:
#ad


They are two different systems.
Good luck finding the issue - hopefully it's nothing spendy.

 

[cerberusiam]

Can you absolutely verify that the vibe only occurs in OD?



Could it possibly be only in TC lockup the vibe happens?



If you can verify the vibe is in OD only I would uspsect you have a transmission problem. Chekc the OD housing and make sure it is not cracked where it mounts to the trans body or t-case. A flex point there could introduce a vobration under certain circumstances.



See if you can make it change with TC lockup. The TC can start going south and drive vibrations also.

 

[LNaugle]

Also check your bellhousing bolts... . We have seen when the rear u-joints get "hard" it will crack the overdrive housing and/or loosen the bellhousing bolts... .

 

[Gibbs]

Prairie Dog, no offense taken. I guess my terminology is confusing.



I jacked up the rear of the truck on jackstands, chocked front tires, and ran it up to speed--at about 1800-1900 RPM the vibration is bad. I got under the truck with the trans in D1 and parking brake dragging slightly as to make rear driveshaft spin slowly. With a sharpie rested on a jackstand, there is definitely some runout on the rear shaft as evidenced by the marks it made. Don't have magnetic base and dial indicatior to know how much... Well, I put the trans in N with parking brake on and ran engine up to around 2K and the vibration is still there, although not as bad as when the rear is spinning, but still very noticeable. I cant see any defects in OD housing and I checked bellhousing bolts-- the bottom 2 weren't as tight as they should be, but the others were good.



Due the runout on the rear shaft and the recent u-joint change, I'm going to have the rear driveshaft rebalanced to help with the extra vibration at speed.



As far as the vibration in neutral, I'm not sure. The engine and trans mounts look normal to me with no apparent damage. So I don't know what would cause excessive vibration at only that narrow RPM range (roughly 1800 to 2000) unless its something like flexplate, torque converter, or engine damper going bad. Thanks for the replies so far.

 

[K5IP]

Gibbs,

Does your truck have the large balance weight on the hose between the power steering pump and the brake boost system? I think your truck was made late enough so that it was included, but----

My 03 did not originally have the weight and a vibration did occur, even when stopped, at about 2000 RPM. You can check by making sure the weight is present, and if not, try zip tying the two hoses together as a test.

I ended up buying a new hose (with weight), and now all is smooth.

Rog

 

[Gibbs]

Yes sir, it has a heavy steel semi-circle weight on one of the hoses.
I got the driveshaft back today and he said it definitely needed balancing. I put it in and its no better--at about 70 and above, sometimes the rearview mirror vibrates enough to distort the images; like double vision. Its terrible.

I pulled the inspection cover on the underside of the bellhousing and watched everything spinning at idle. I rested a socket extension gently against the flexplate near the ring gear and there's definitely some runout. How much is normal?

My buddy said there's a place in Atlanta that deals with vibration analysis on autos and he's trying to find the number. They fixed his cousin's Mustang by running it on a dyno and looking for the source of the problem (maybe they have some sort of instruments to localize vibration?) and found the pinion angle was off a couple degrees.

I checked angle on my truck and the transfer case output is angled down about 6. 5* but the pinion is only angled up about 4. 5*. Could this 2*disparity cause any other vibration??

The part that's throwing me off is the vibration I get while sitting still and revving to 2000 RPM and above. Maybe that vibration is getting amplified at highway speed to cause even more intense vibration. I don't know, but its really frustrating me.

 

[Bob4x4]

A shop that specializes in repairing vibrations will measure the frequency ,do sme math and get very close to what is causing it

 

[Gibbs]

This evening I pulled the engine damper for a closer inspection. Everything looks great and the 2 witness marks on the hub and ring are dead on. So I ruled that out as causing any problem. While I had the serpentine belt off, I revved it up and it didn't feel any different; so I know an accessory isn't causing any problems.



Its interesting to note that most of the vibration is felt thru the steering wheel when sitting still and revving it up. Its not nearly as noticeable thru the seat. My friends truck is very smooth. I would think if there's a problem with the crankshaft or reciprocating assy that there would be other issues. I'm leaning toward the flexplate and or torque converter, but I don't want to just throw money at it. After the first few dollars, I'd be broke :-laf



Do you think I should pull the transmission back to have a closer look at the flexplate? As far as I know it's never been pulled. I wonder if the flexplate to crank bolts are still tight?



I'm also wondering how much of a difference the 6. 7L damper would make. My buddy who does heavy truck repair can get me the damper and fan pulley for about $250. Its sorely tempting...

 

[EDankievitch]

You say that the vibration is there with the truck out of gear and running at a fast idle (reving the engine) I had a simular problem with my 05 manual trans. With my truck it would buck when coasting while using cruse. When the engine was cold you could bring it up to 2500 rpm (out of gear) and it would run smooth as it warmed up it would start to buck and miss fire. Turned out to be a cracked injector tip. The crack would close up some when cold and pen up when it got warm. The crack over fuel that cylinder the computer would see the engine accelerate faster than it should and cut back on the fuel to the other injectors, it all happens very fast. My lie o meter (Overhead MPG meter) was reading that I was getting 45 MPG when this was happening and I had aloty more smoke than normal. I'd start with a set of good new injectors from Dynomite Diesel and I'll bet your issue goes away. I went with a set of stage one's and the engine never ran smoother.

 

[Gibbs]

I've thought about pulling the injectors and having them tested but there's several more things I'm gonna try first. Ive heard of injectors causing engine vibration before. Mine does it whether the engine is cold or warm.

 

[BDaugherty]

After reading this post, I'm leaning towards injectors. That said, I would like to know what the rail pressure is doing while you are having the worst vibration. Is it steady or fluctuating? Also, I have all the adapters if you want to check return flow to see if that tells anything. Honestly, I would like to find someone with a scan tool that will allow you to run a cylinder contribution test. You may very well find one or two weak injectors and the whole load/engine speed thing is just when it is more pronounced.

 

[Gibbs]

Bill, can your scan tool read rail pressure? Otherwise, I'm not sure how I'd check it. Regarding cylinder contribution, maybe I can talk to Shane or Priest to see if they can hook my truck up and see if there's anything amiss with the injectors. I'd really like to rule them out without having to spend a whole bunch of money (that I don't have. ) About the return flow, wasn't it kind of inconclusive on your truck? Not sure if it'll tell me anything or not. But if you think it will, I'd like to enlist your expert assistance.

I guess injectors can do some strange things, but it just seems odd that it starts up so quickly (even when it was below freezing) and runs so good. When I stab on it from a dead stop, it'll light up whatever tire has less traction, puff a little black smoke, and its down the road like a scalded monkey. Maybe I don't know what I'm missing... Hmmmmm...

 

[Gibbs]

Update... Right now I'm not much worried about the engine vibration itself. Its not much different then BDaugherty's truck, so for right now I'm concentrating on the driveline. It has a high frequency vibration at between 70 and 75, which seems to be commonplace with these trucks #@$%! Bill and I narrowed it down to driveline since it's speed dependent and not RPM dependent. For example: at 2100 RPM and 75 MPH it vibrates, but if I downshift to 3rd and run it to 2100 RPM, there's NO vibration--and if I run it up to 75 in 3rd (which is approximately 11 hundred thousand RPM), then the vibration is still there, although not as intense.



I stumbled across an old thread from Carson Dodge discussing vibration and ran through several things trying to find a cure. Here's what it said:





"With the introduction of the hydro-formed frame in 2003 a new "problem" developed. The old C-channel/I beam frames tended to dampen noise and vibrations. The new hydro-formed frames tend to amplify noise and vibrations and transmit them throughout the body. The Cummins has a couple of resonant points, like any rotating machinery, and can create this problem. The engine, along with several other components, can transmit various vibrations to the frame. The one that most people complain about is around 70-75 MPH (2000-2100 RPM).

In 2004 I wrote an article in TDR about these vibrations and the various solutions we had discovered over time. I want to emphasize that there is no one solution. Each truck is different. Below is a breakout of what we've found at Carson Dodge so far:



Component at Fault - Frequency (on a scale of 1-10)



Transmission: Add rubber between transmission mount and cross-member. - 9



Rear driveshaft: bent, misaligned U-joints, incorrect pinion angle, out of balance, sloppy center carrier bearing. - 9



Front exhaust hanger: bend, cutoff, or replace all. - 8



Tires: balance, out of round, and tread design. - 7



Skid plate: remove. - 3



Power steering hoses: install updated version, TSB 19-008-03. - 4



Front driveshaft: bent, out of balance. - 2



Transmission dipstick tube: tube vibrating against heater hose. - 2



Loosen engine/transmission mounts: either drive a short distance or jack up engine/transmission and allow to "settle", then re-tighten. - 2



As you can see, each vehicle responds to a different approach. It's strictly trial and error. The solutions, assuming there aren't defective components, revolve around isolating the engine, transmission, driveshaft, etc. from the frame.

The most frequent complaints come from 4X4, automatic, QC, LWB trucks. The number of trucks impacted with this "quirk" has gone down steadily since 2004, although we occasionally still get the complaint.

Currently the only thing Dodge will pay for is to check the driveshaft with an inclinometer to determine if the angle is within spec (+- . 5 degrees). John"







I tried the following things one at a time with no apparent change: Added rubber under trans mount, shimmed trans mount to make u-joint angles match, removed front exhaust hanger, had rear driveshaft straightened (he was able to "remove" some of the runout) and high speed balanced at another shop, swapped wheels/tires from a buddy's truck, and checked pwr steering hoses (mine has vibration dampening weight. ) After running through these, I removed front driveshaft and it seemed to narrow the speed range of the vibration and reduce it a little. I'm leaving it out until I do some more testing. Now I have a new problem with rear output of the t-case leaking. I'll update as I make further progress.

 

[Prairie Dog]

Good info - thx for the update. There's some stuff there that I've never heard of and could come in handy.

 

[Gibbs]

Problem Solved!

I very excited to say that my truck is now vibration free--well as much as a 4x4 Cummins can be, anyway.



I replaced the tail cone on the NP273 not only to get a new seal, but also a new support bushing that the slip yoke rides in. I was planning on replacing the slip yoke when I replaced the tail cone, but it turned out to be $190. I told my parts guy that there was no way I was going to pay that much and I'd rather put that money toward a whole new driveshaft. He said hold on let me check--the complete driveshaft is only $278 and I have one in stock. I told him to send it my way. So for only $323 shipped to my door, I have a brand new driveshaft. The first thing I noticed was that the tube is the same diameter from end to end, whereas my old one necked down at each end (or was larger in the middle). The yokes welded on the tube have a whole lot thicker ears and the pinion flange has a little different shape, too. It also included a damper on the slip yoke.



When I test drove the truck this afternoon, I was nervous when approaching 75 MPH. When I got it up to that speed, there was no more vibration!! I stayed at 75 for a minute, then accelerated up to 95 and it was smooth sailing. I can't tell ya'll how relieved I am to have this fixed 'cause it was driving me crazy. Thanks to Brian Condley at Dallas Dodge for the great customer service and low prices. And thanks for all the suggestions from TDR members. I appreciate it