New Noise Under Truck

[StephenDelany]

Hello Everybody,

I have come to the turbodiesel "Oracle" once again to try to figure out what the source of a new (I don't like it) noise is.

This noise will only occur when I run up the RPM's for a "jackrabit" start from a stop. If I leave a light at a regular leisurly pace it does not happen.

The only way I can describe the noise is a cross between a squeek and a whine. It sounds like a short "shing" as the clutch is let out and the drive shaft begins to launch the beast. There are no abnormal vibrations as I go up through the gears and it does not reappear at the other shift points, only at take-off.

It sounds like it is located towards the rear of the truck and almost has a sound like something in the driveshaft is slipping a little bit or using the shaft as a resonator.

The clutch seems to be fine in it's take-up and never shows any signs of slipping or pulsing so I don't think it is part of the noise. Likewise, the rear end isn't making any funny nioses at 70 MPH with a 6500 Lb. load or around town empty.

I put myself in the care of the Diesel Doctors at TDR on this one because I am stumped... Any hints or things to check from the ranks would be really appreciated. (Sorry about the Book)

Steve

 

[StephenDelany]

Man, this doesn't make me look very good when I have to reply to my own post!... . Ouch.

I really could use some help on this one. I know I don't live out West or own any livestock but I do love this dman turbo diesel Dodge.

Thanks to anyone who has got the time.

Steve

 

[BK]

by any chance does it sound like the same ring you would get if you tap on the driveshaft tube with a wrench?

 

[StephenDelany]

Hi BK,

The sound is not like something hits the drive shaft to ring it but more like something twists or shifts in it to create the noise.

 

[BK]

Ok. I guess I was trying to key in if the sound - sounds like it could be coming from the driveshaft...

Idea is, under hard acceleration, you get some axle wrap, maybe the UJ at the axle is a bit tired out and warn. . as the axle wrapps and the pinion points down it sticks a bit, apon rotation it clicks... . ringing through the driveshaft... it goes away cause once the truck is moving the springs unload the energy into forward movement and the pinion rises. . no more clicking UJ...

Cheap and easy thing to replace. Also usually the 1st thing to wear from jack rappit starts.

Since they arent greasable from stock, they get dry quick, wear faster and can become clickly.



If it is the UJ, you have X number of launches and the drive shaft will be on the ground... . (it's written on the driveshaft somewhere, but noone knows where and you can never find it, but it's as sure as a bear poops in the woods, that UJ will go someday)...

 

[LSMITH]

I would also check the slip joint in the driveshaft to see if it is dry, they will make some strange noises if dry or worn and binding.

 

[StephenDelany]

Hey BK and LSMITH,

I gotta believe you guys are on the right track as this thing definately seems localized to the drive shaft behind the cab. I just crawled around under there a few minutes ago and I could not see or feel from shaking or turning a problem. I did notice a 2" area of light slow oil seepage around the bottom of each axle tube as it goes into the cover where the rear brakes are. I hope this small weep is normal...

Anyway I'll get out my service manual and see if it can walk me through some diagnostics for the UJ at the Diff' or the Slip Joint.

Thanks alot.

 

[ToolManTimTaylor]

Another to look at.

Check the Body mounts (Rearward corners of the cab and the forwardmost on the bed) Under hard accel the truck is twisting up a bit and I have seen a loose bodymount that would let the rubber squeek a bit as the frame and body flex. you can hear this noise quite asily as the sound travels easily between the space of the bed and cab.

 

[BK]

I agree with LSMITH that the slip joint is another possibility.

As the pinion dips during hard lauch from the axle wrap, the slip joint has to slide out. . if it's dry or binding you can get the same noise.



And it's even easier to try to eliminate.



You just need to unbolt the lower UJ. (1/2 of the work to replacing it). Make a mark with chalk at where the 2 halfs of the slip joint of the drive shaft come together. Slide the lower driveshaft out.

Inspect for dirt, wear...

It's probably dry and a bit rusty. Gets some chassie lub and grease up the splines. You have two choice. . slide it back together again by aligning the marks. . don't be off by 1 tooth. . or the phasing of the UJ will be out. or you can turn it perfectly 180 degs. Some times when there's wear. . turning it 180 degs will buy you time and get rid of the noise. . besides the greasing.



For the UJ... while it's unbolted, just carefull slide off each end cap... one at a time, inspect put it back on, and do the other, don't let the needle bearings fall out. . . If the needle bearings are greased (no dirt, rust) and shinny and no blueing from heat they are ok... but that's only 1/2 . you would need to press out the other two to inspect. . at that point you might as well as replace it. If you can't press them out, most decent auto shops will sell the UJ, you can carry in the driveshaft and have them press out and press in the new one. . so it's just a bolt in assy at home.

The seats in the yoke of the pinion and the caps should be clean and not worn, burnt or chipped up or should not be bright and shiney. . if shiney the uj cap has been spinning in it's seat. If chipped, the UJ wore or the Cap bolts were loose, or the the cap failed... and the cap was slapping around in there. The seats should be clean, half round. . a bit of light rust is ok. . since the cap is not supposed to be moving it the seat or cap of the yoke.



Hope this helps. .

It's only a 1 wrench jop. pretty easy.



Bob

 

[StephenDelany]

Wow BK, You da Man!

That was a realy great post and gives me all of the hand-holding I might need when take apart my drive shaft. Thanks very much.

When you talked about the slip joint and how it responds to axle wrap it makes a lot of sense how that noise might be generated at the moment of launch. I bet I will find it all tight and full of crap.

I owe you guys a FISHIN' TRIP! (Saltwater Only)Oo.

 

[Mac]

BK

You sound pretty knowedgeable about driveshaft noises. My Y2K 6 speed makes a noise when starting off in 1st or 2nd just as the clutch gets full out and it sounds like someone hitting the driveshaft with a small hammer lightly. Been doing it since new(43000miles). Dealer heard it,agreed it made the noise and said they all do it to some extent and there was nothing to worry about. Have you got any thoughts on this?

Thanks a million

 

[BK]

Thanks, I've lived with , run, fixed, broke, make sure they'd get me home, trucks since 1980. I know what I learned by living through it, thats all and there's a lot I don't know. I spent more time under MY trucks on PM and inspection than repairing... so I wouldnt get caught on a trip or in the middle of the woods cause of something I could prevent. My buddies thought I was a bit over the top with it. . but I was the one that got calls at night to get them unstuck or tow them out of somewhere and get them home. Listening to these noises and know what they are and know what they arent by checking. . increases your chances of not dropping a drive shaft.







If it even does it on easy off line accelerations, I'd be wondering.



I've been in my buddies HO 6 spd and I don't hear anything from the drive train. I hear more from mine with the auto going from forward to reverse,, the clunk and clank. . which is all the lashes being taken up, yup normal, been there since day one... . . . When I let out easy on his 6spd, and drive nice (it aint mine. . so have to be nice)... I don't hear anything from his. And once you've been going forward... and you stop at a stop sign and don't roll back, you mostly likely don't keep hearing all of that lash being taken up again. That's what i've noticed on his 6spd HO.



But he doesnt have 43K.

The y2k also had an issue of loose rear leaf spring ubolts.

Another TDR gent said that he kept tighten his, they kept coming loose. With the axle shifting, you'll get a ting sound that can run through axle tubes and and sound like the drive shaft.



If I were you I would double check them for proper torque and also do what was suggested earlier in the post... check you slip yoke and check all your UJ's.

If they click, you get that ting sound from your drive shaft tube. . same with the slip yoke at times. . I've had the slip yoke make no sounds, but offer some vibrations at certain speeds when bad. But all of those old slip yokes I had in different trucks could be greased , which I always did. My Ram's yoke has no grease fitting.

So they can run dry and get noisey.



Go through it all once, so you know what you have.



I've got like only 4 grease fitting through out my whole Ram. . I can't understand why freakin dodge did that. Atleast on my buddies 01 they put grease fitting on everything in the front end that should have them... but he doesn't have them on his drive shafts and UJ's either.

 

[BK]

Oh guys. . it just poped into my mush of a brain. .



I have a QC with an 8ft bed. . So I'm thinking of a driveshaft that has a hanger bearing and slip joint right after the hanger bearing.



If you have a standard cab with a short bed I know there's no hanger bearing and I thing the slip joint is in the output of the transfer case ( yoke on the driveshaft just slips into the output of the transfer case like a 2wheel drive autotranny) . . none in the middle of the driveshaft. . but not 100% sure about these trucks and at what wheelbase or combo DC starts putting in the hanger bearing setup.