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Discussion Starter · #1 ·
I have some pretty serious vibrations in my 4Bt. It's installed well, but rubber isolators aren't the best, soon to get upgraded. But I just got to wondering about the NV4500 & u-joint.

I had a custom driveshaft made by one of the top shops, Tom Woods Custom Driveshaft, so no doubts there. But, I installed a used 6BT u-joint/harmonic balancer on my NV4500 output shaft [2WD]. Wondering if others are using the 6BT damper & u-joint assembly on a 4BT?

Occurred to me that maybe it's made for 6BT and doesn't want to handle 4BT vibrations or something? I don't think that's the problem, but thought I'd toss it out here. Just poking around looking for solutions.

Vibrations are throughout the rpm range, disappear when I put in the clutch, and tend to get a little worse at higher rpm's in every gear, most noticeable in 2nd, 3rd & 4th, least noticeable in 5th. Again, vibrates in every gear at any rpm. If I had to compare it to something I'd say it's at least as bad as 2 dead plugs on adjacent cylinders on a gasser V8. Thanks!

JimmieD
 

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sounds like engine vibrations, i would think a balancing issue would change with rpm's/speed

is it hitting anything on the cab/frame? exhaust well isolated? how heavy is your truck?
 

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Discussion Starter · #3 ·
Doesn't seem to be hitting anywhere, I checked it all out the other day. Exhaust is isolated, only the metal/rubber hanger straps straps touching frame. Trucks' a full sized '67 Dodge 2WD, about 5,800 lbs.

Had a fuel issue, probably a clogged up injector, which made it much worse. I guess it blew that petro snot booger cause that cleared up. I suspect it might be injector problems, but wanted to ask about the damper, just in case. You know, fishin'....
 

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I used a stock damp on the white ford I did this year and it looked good but when installed it was just like you talked about .I ordered a new one and reblanced and the vibs were gone.I would pull the shaft and have it balanced to see if it is the damp.

Scott
 

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when you put the engine in, did you have it match the OEM output angle?

The ouput yoke on the 4500 MUST be at or just under the same angle as the pinion angle of the rear axle....

This site explains it pretty good.
http://www.4x4wire.com/tech/pinionangle/

It's written for guys who swap different axles into their vehicles (Jeeps!), but the principals work both ways. You can measure the angle from the rear pinion yoke with a cheapie angle finder (home depot, lowes, rona) and the angle at the output yoke on the transmission.
I'll guarantee they're not the same.

Hope this helps :)
-Scotty
 

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Discussion Starter · #6 ·
Thanks, Scots!

I was sorta suspicious about that output yoke, wondering why somebody would want to get rid of a good one? Could be the elastomer insert got torn and he replaced with another.

Driveshaft angles are really tight on this install. The absolute minimum is maybe 8* and mine came out at 9.5*-10*, darn near straight! Front/rear are matched.

But I thought about it some more and if it was driveline it would probably still vibrate when I put in the clutch, whereas now the vibration stops 100% at clutch disengage. I'm thinking something else is out of whack, maybe flywheel or part of clutch assembly? Not only that, but I don't recall this much vibration a few months back.

I've never ridden in any other 4BT so I can't really 'compare' my vibration to another. Hmmmm, maybe I'll hijack a chip truck on its route and demand that he drive me around the block or I'll stomp on all his potato chips....:rasta:
 

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the rear pinion will 'torque'/ point upwards when load is placed on the drivetrain. This will throw the angle out aprox 2°, which you'll feel. Can do a few things.

-Shim the pinion to point down a few degrees, so that when it torques up, it's at the proper angle.

-add a "torque bar" or "traction bar". It's basically a control arm that goes to a fixed point on the frame and prevents the axle from wrapping up.

-Scotty
 

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Something is definetely out of whack .. My guess is probably driveshafts or a bad u joint as well. Possibly a transmission output bearing but I doubt it. The 4BT vibrates but not that bad. There is not difference between a trans for a 4 and 6 cyl, they are not 'balanced' for a particular engine. Hopefully you can figure out what it is...
 

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Discussion Starter · #9 ·
Guys, I really appreciate the great feedbcak! I think I failed miserably in describing the 'perceived' problem!

The vibration is consistent under torque or cruise free-wheeling and anytime the engine is working. It stops completely when the clutch goes in, or I let off the throttle. It doesn't act like a driveline or axle or pinion angle problem, I've had all of those in trucks in the past. I'm marginal on angles but it doesn't quite fit the pattern for driveline problems.

Y'all got me thinking though. It got an injector snotted up a while back and vibrated a whole bunch more. I was e-mailing back & forth with Paul in NY trying to figure it out. All of a sudden it blew that diesel snot booger through the injector or something and got a whole bunch better. But, that problem was very similar to the continuous problem.

So, is there a way to evaluate injectors without removal and a pop test? any normal clues to funky injectors? I think I got the valves adjusted right which helped, but I just wonder if it could be an injector imbalance of some kind? Back when I was trying to get the engine started right after install I noticed that one injector bled different than others, not leaking out as much fuel or air bubbles. Any clue there? Looking for at home-tech, as usual hah! Thanks for the great tips so far....

JimmieD
 

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Guys, I really appreciate the great feedbcak! I think I failed miserably in describing the 'perceived' problem!

The vibration is consistent under torque or cruise free-wheeling and anytime the engine is working. It stops completely when the clutch goes in, or I let off the throttle. It doesn't act like a driveline or axle or pinion angle problem, I've had all of those in trucks in the past. I'm marginal on angles but it doesn't quite fit the pattern for driveline problems.

Y'all got me thinking though. It got an injector snotted up a while back and vibrated a whole bunch more. I was e-mailing back & forth with Paul in NY trying to figure it out. All of a sudden it blew that diesel snot booger through the injector or something and got a whole bunch better. But, that problem was very similar to the continuous problem.

So, is there a way to evaluate injectors without removal and a pop test? any normal clues to funky injectors? I think I got the valves adjusted right which helped, but I just wonder if it could be an injector imbalance of some kind? Back when I was trying to get the engine started right after install I noticed that one injector bled different than others, not leaking out as much fuel or air bubbles. Any clue there? Looking for at home-tech, as usual hah! Thanks for the great tips so far....

JimmieD
Hmm.. Sounds like what you want to do is a power balance test. Only thing is, I can't think of a way to do it on a mechanical injection diesel. Well.. Maybe one way:

Would cranking it up, then cracking an injector at a time let you do a PB test? I'm a thinkin' that if it doesn't shut it down, the governor is going to compensate and kick it back up to idle RPM, so no RPM drop. (Also, take FULL precautions to avoid getting a hot shot of diesel into your body.. NOT to be taken internally..)

Another thought is to take a mechanic's stethoscope and listen to the injectors and the lines to see if any sound odd in comparison to the others. If you've got one that's not a poppin' the way it should, you might be able to hear it.

Just a random thought or two..
 

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i've never experienced these, but what about a bad pilot/input/throwout bearing? or a broken clutch plate causing it to be imballanced. just thinking outloud...
 

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This has the characteristics of either a failing pinion bearing or rear driveshaft u-joint. Take her for a short ride and crawl underneath to see if anything is heating up.
 

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Discussion Starter · #13 ·
More great info, thanks!

Machman, I can crack injectors with engine running, no problem. I'll take precautions but my experience was that my pressure isn't real high that I'd shoot myself. They just leak out some fuel [and bubbles] around fitting. I recall that one particular injector kept blowing bubbles, so maybe that's the problem! I also recall that one injector, I think that one, didn't have as much change in engine note, like rough imbalance.

Will do on the stethoscope!

Durango, I'm pretty convinced the pilot bearing is good. I used the good needle roller one, new, and greased it well. Clutch, pressure plate and throwout all new, flywheel lightly resurfaced. I've experienced the bad pilot problem on other installs and this one seems okay.

Bob, I'll check those out. I used a Spicer 1450 on driveshaft joints, so it takes a lot to blow one! Pinion makes a slight whine but other normal 'bad pinion' symptoms aren't there. Not to say it isn't going south, but seems okay. I'll check it out next trip to town!

It just 'feels' like engine related. Might need a set of new injectors or something. I'll keep poking around, THANKS guys!
JimmieD
 

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I was about to say crack the injectors one by one. Also the manual says to use the technique so it is OK. I usually put a junk towel over the line of injectors because it will spray everywhere...

Other than that you can also see if there is any plan in the driveline by getting under there and muscling it around. See if there is any play in anything. And it could even be a badly out of balance driveshaft too, for what its worth, or again even a blown u joint. Hope it helps...!
 

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Hi JimmieD, as suggested have a crawl about underneath checking for play in Ujs and the pinion. Also taking the injector feeds off one at a time might tell you something, but taking them out and getting them tested is going to be best bet if you run out of other ideas. Sometimes vibration can seem to be from one thing and turn out to be something else. You mention an injector problem that cleared up and the vibration was much worse , could it be the injector problem is still partially there? Just put a double cardon prop on my dads Rover and that cleared his vibration/noise .

Gaza
 

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Also a lot of injectors run fine but are shot / need to be rebuilt, lost power, efficiency etc.. My recommendation is to pull them also. Also, the cheap Harbor Freight diesel compression tester ($25 or so) doesn't advertise it but it has the Cummins adapter and works just fine. Might as well do a compression test while you have them pulled...
 

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Discussion Starter · #17 ·
More excellent feedback, thanks!

I'll check the driveline but can't imagine it's bad, Tom Woods shop is one of the best and he made up a whole new stick, and I can see the balance washer welded on. I have a slight pinion whine but no other obvious indication of driveline problems. I'll check!

The more I think about it the more I'm leaning towards injectors as mentioned. Yeah, DC, one thing that bothered me when I bled them before is that they didn't all seem to squirt fuel the same. Hard to tell if a fuel line is cracked opwn exactly as far as another though. May be time for an injector pop test and a compression test. I just don't do bad news really well....
 

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More excellent feedback, thanks!

I'll check the driveline but can't imagine it's bad, Tom Woods shop is one of the best and he made up a whole new stick, and I can see the balance washer welded on. I have a slight pinion whine but no other obvious indication of driveline problems. I'll check!

The more I think about it the more I'm leaning towards injectors as mentioned. Yeah, DC, one thing that bothered me when I bled them before is that they didn't all seem to squirt fuel the same. Hard to tell if a fuel line is cracked opwn exactly as far as another though. May be time for an injector pop test and a compression test. I just don't do bad news really well....
don't worry, my buddy's 24v, he blew the vp44 on it, got a new one and 2 weeks later noticed a good bit of coolant leaking out the back of the block.... talk about bad news! He just put out the effort of a 5 speed swap, so he's pretty broke too...
 

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Discussion Starter · #20 ·
Man, Durango, don't stand too near your buddy if it's cloudy out and thundering! ZZZZzzztt! Call him Smokey hah!

You know, Scout, I wonder if you're not on to something there!?! Hadn't really thought about that, figured I got it phased right.... Sure goes along with what DC, BobS, Gaza, Fitty, and various Scots are suggesting. I remember I was really exhausted at that time of hookup, never a good thing!

With the incredible mass of that 6BT harmonic balancer it sure could explain things. Plus I drove the truck that my rear axle came out of on one long trip, and a couple of shorties: NO rear end howl! Now, hmmmmm, a little bit of complaining out of it.

I know what I'll be doing tomorrow [Lord willing]! Soon as I can I'll check injectors & compression too. If I can sell my other truck I'll just spring for a set. Thanks for all the great assistance guys!

JimmieD
 
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