Odd ZF noises

[BrandonMag]

Over the past couple of months I've noticed what appears to be a high-pitched whine coming from the transmission. However, it happens only when heavily loaded down (like if I've got more than 2000 lbs in the bed or am hauling my 6000 lb trailer). The noises don't seem to change when the clutch is engaged or disengaged.

I uploaded a video I took yesterday:

http://www.youtube.com/watch?v=HsUw9qRpPjg
(It's kind of long, the time the noise is most noticeable is around the 2:30 mark.)

I followed a recommendation here and pulled off the inspection plate on the tranny and now know that I've got a DMF. I could see four of the flywheel springs and they all appeared to be in good shape. Is it possible that the weird noises my transmission is making are related to the DMF wearing out? Or could it be that the transmission itself is getting worn out?
For the record, this truck has got just over 171K miles. The truck was owned by one family until I bought it in October of '09. Talking with the PO, this truck was never abused or wheeled. I've put about 11K myself and have been very meticulous about maintenance. I haven't abused it but have hauled a lot of firewood and my trailer several times.
When it's not loaded down, the transmission does make a little noise but nothing that seems excessive to me. The problem is I bought this truck to haul wood, gravel, my trailer and whatever else may need haulin'.

 

[IDIDieselJohn]

Did you check the fluid level?

Could be low on fluid, friend of mine his 5 speed F150 (Mazda tranny, M5OD) was doing that noise all the time in all gears, I checked the fluid, and was pretty low, when I toped it up, took about a 15 min drive, and the noise completelly disapeared.

 

[BrandonMag]

Did you check the fluid level?

Yep, I've checked the fluid level twice in the last 1000 miles in the hope that was the cause. No go. It's full.

Any other ideas?

 

[towtruckdave]

Did you top off the rear axle lube and transfer case atf?

 

[BrandonMag]

Did you top off the rear axle lube and transfer case atf?

Yes. The transfer case has a very slow leak, so about 200-300 miles ago I cracked it open and added about 12 ounces of fluid, 4 or 5 of which was Auto RX to help slow the leak. So far, it doesn't seem to have helped. It's been several months since I've checked the rearend, but last time I did it was FULL.

I'm about 99.9% sure the noise is coming from the transmission. Since I can't get underneath the truck when it's making the noise I could be wrong, though.

I'd really like to get this problem solved ASAP. I've got all of my ducks in a row to install the turbo, but I don't want to put it in just to have to drop the tranny 1000 miles later. I'd rather fix whatever is wrong with the tranny (be it needing a rebuild because bearings are getting worn out or just replacing the DMF with a SMF) and THEN install the turbo.

 

[RLDSL]

If it only changes when you are loaded down that leaves 2 options. Either you have a ujoint going out and it is starting to make noise when the driveshaft changes geometry when you load down the bed, or you have a wheel bearing going out. My vote is for a ujoint. Just out of curiosity, when were they greased last?

 

[BrandonMag]

If it only changes when you are loaded down that leaves 2 options. Either you have a ujoint going out and it is starting to make noise when the driveshaft changes geometry when you load down the bed, or you have a wheel bearing going out. My vote is for a ujoint. Just out of curiosity, when were they greased last?

I guess I haven't been as meticulous on my maintenance regimen as I should have been.

I haven't greased any of the u-joints since I've owned it. Looks like it's overdue.

 

[IDIDieselJohn]

Any grease fitting should be greased every oil change!

When first buying an unknown vehicle, I always greased everything till the seals blow open and grease comes out, then after that, at every oil change, I give 'em 2 pumps of my grease gun and that's always enough to grease 'em well, but not to pop open the seals.

 

[RLDSL]

Any grease fitting should be greased every oil change!

When first buying an unknown vehicle, I always greased everything till the seals blow open and grease comes out, then after that, at every oil change, I give 'em 2 pumps of my grease gun and that's always enough to grease 'em well, but not to pop open the seals.

Even using the insanely high dollar Amsoil series 2000 racing grease it takes a bunch more than 2 pumps of grease to fill up ujoints. Once they get all teh old stuff worked out of them and there's nothing but the good stuff in there you can go a bit longer in between greasings and it won't take as much, but it takes quite a while to reach that point and until then it usually takes about 8 or so pumps on each joint to get them full. Any less and you've got a dry corner while the regular grease works it's way out.There's a darn good reason for greasing every change ( on in my case more often since I have a bypass system, I haven't changes my oil in around 2 years ).

 

[BrandonMag]

Okay, I crawled under my truck a couple of hours ago and checked out all seven of the u-joints. Not a one of them has a zerk fitting for a grease gun. And I just bought a brand new grease gun at NAPA so I could lube them up.

They're all dirty and could quite possibly be over ten years old (I have absolutely no idea, though). What say you, knowledgeable gurus?

 

[RLDSL]

Okay, I crawled under my truck a couple of hours ago and checked out all seven of the u-joints. Not a one of them has a zerk fitting for a grease gun. And I just bought a brand new grease gun at NAPA so I could lube them up.

They're all dirty and could quite possibly be over ten years old (I have absolutely no idea, though). What say you, knowledgeable gurus?

Non greasable joints on a 4x4, that's a real joke. Yes you can have sealed joints on a pavement cruiser and get by, some do real well for a set lifespan, but on a 4x4 it's a recipe for disaster, because 4x4s go places, and get submerged and water pushes grease out easily and you need a way to replace it not to mention ten years is admirable for any ujoint, on a 4x4 with no zirks, it's got to be some kind of record.

 

[Brianedwardss]

Both my IDI's have non-greasable joints. As they go bad I'm gonna replace them with greased ones.

When my rear-end started to go out on my '88, it slowly developed a high pitched whine/shearing sound. But the noise in the cab was clearly coming from behind the back window and not at my feet like a tranny noise would. I also had an 84 GMC 6.2l diesel truck that started making a whiny noise under deceleration, and it was the rear most u-joint. I didnt figure that out till it started having enough play as to vibrate the truck at hwy speed tho. How much play do your u-joints have? Try pushing the driveline up/down, side-to-side at each joint. If it's doing it with the clutch in, I'm thinking this noise may be rear of the transmission.

If the noise is somewhat predictable, maybe create the right circumstances and drive with the rear window and both door-windows open, maybe find a nice cement median or building to echo the sound up to ya. If you've got a mechanically inclined friend, take 'em for a ride and have 'em stick their head out the window a bit.

 

[BrandonMag]

How much play do your u-joints have? Try pushing the driveline up/down, side-to-side at each joint.

I'll take a look and get back here in a couple of days.

 

[MR.T]

Thinking it's not the trans as well. If it only makes noise with weight on the tail end, and the noise stays when the clutch is pressed -- how would the trans be affected by weight with the clutch depressed? Maybe if the tranny was getting hot with the extra load and the temp is still high when pressing the clutch -- but this thought is only a possibility if it takes heating time to hear the noise with a load. So there's a potential question, does it take a while to heat up and make the noise?

Anyway, u-joints were already mentioned -- Very possible, but I'm thinking it's also possibly a rear wheel bearing. Noises can travel through the metal making the source seem whatever is close. Maybe have someone drive while you are in the back listening at various places (not OSHA approved). Sharp cornering is sometimes a good test for wheel bearings, they usually change noise as weight transfers to the outside in a corner.

 

[NTOLERANCE]

U joints with grease zerks are weaker than ones without. Since the joints must be hollow to allow the grease to access the end caps.

On all my trucks, I have never run the greaseable ones on anything but a daily driver. Same for my drag cars.

To each their own, but it something to consider.