Noisy 4WD

[RodMorris]

My 2007 5.9 with manual transmission is making terrible crunching noises in 4WD. It has 470000 miles on it. I replaced the chain and sprockets a couple years ago when it stretched enough to start slipping. Now it's making a crunching noise in 4WD with the hubs locked in. I do have a Spyntech hub conversion on it. It does not make the noise if the hubs are not locked. I've had the transfer off 3 times in the last couple months and I just don't see anything wrong with it. I have had the hubs apart a couple times and just degreased and cleaned them and put them back on with just oil on them. I even took the cover off the front axle to see if anything looked bad in there. It all looked fine. All the driveshaft and axle shaft u-joints seem to be fine. I hate to spend $2500 on a new transfer case - I should be able to fix this one. Anybody have any clues what's wrong?

 

[Ozymandias]

What's it doing with the hubs locked but shifted 2WD.

 

[RodMorris]

No noise in 2WD with hubs in or out.

 

[amtc]

My 2007 5.9 with manual transmission is making terrible crunching noises in 4WD. It has 470000 miles on it. I replaced the chain and sprockets a couple years ago when it stretched enough to start slipping. Now it's making a crunching noise in 4WD with the hubs locked in. I do have a Spyntech hub conversion on it. It does not make the noise if the hubs are not locked. I've had the transfer off 3 times in the last couple months and I just don't see anything wrong with it. I have had the hubs apart a couple times and just degreased and cleaned them and put them back on with just oil on them. I even took the cover off the front axle to see if anything looked bad in there. It all looked fine. All the driveshaft and axle shaft u-joints seem to be fine. I hate to spend $2500 on a new transfer case - I should be able to fix this one. Anybody have any clues what's wrong?

I recently had an issue with my 4wd making noise in 4wd only. I replaced all u-joints in rear drive shaft and front axles and replaced front drive shaft. I had the transfer case apart and replaced all seals. Turned out to be the new front driveshaft I installed. Cost me a lot of money but I did learn not to trust "new or rebuilt" parts.

 

[RodMorris]

What kind of noise did the front driveshaft make? Mine is a crunching sound, like pea gravel between the gears.

 

[Ozymandias]

Set it on 4 blocks, safe and secure!, and run it so you can maybe find the reason for the noise.
Until then stop throwing parts at it.

I've an idea but without hands on it is a stunt to tell it here.

 

[petersonj]

All the driveshaft and axle shaft u-joints seem to be fine.

What does that mean? How did you check them? What is the history on all of the u-joints?

- John

 

[RodMorris]

I checked all the u joints by turning them by hand to see if they were loose or binding. I've replaced the driver's side axle shaft u joint twice. The second time I put the Spyn Tech hubs on it so they haven't really turned much since then. I had it stuck yesterday and had to use 4WD. It works, just makes some terrible noises. It usually doesn't make much, if any, noise in 4WD driving straight with no resistance. It starts making noise when I turn. So, I'm not sure putting it on blocks and running it would tell me anything. I haven't really thrown any parts at it so far, just inspected it really good.

 

[petersonj]

I re-read your posts and I don't see any mention of ever replacing u-joints on the front drive shaft or axle shafts, so there is 470,000 miles on them?

I suspect that you have one or more u-joints failing. When a u-joint fails, it can reach a point where is not sloppy nor binding, as far as feel by hand. The needle bearings can be crushed to powder and make the u-join seem okay when turned by hand.

For axle shaft u-joints and front drive shaft u-joints to make noise when they are badly worn, the front drive train must be loaded, as in when four-wheel drive is selected and the truck is driven on a hard surface with lots of traction. The noise will always be enhanced during sharp turns.

If you have badly worn u-joints, they will generate heat when operated for awhile under load. You could drive your truck in a manner to force the noise to happen for a few minutes and then park the truck, turn of the engine, and set the park brake. Crawl under the truck and feel each u-joint with your hand. If you feel one that is quite warm or hot, then you have found your problem.

Or, if you have not ever replaced any of the mentioned u-joints, just replace them - they have served you well.

- John

 

[Ozymandias]

Check the air gap between the axle housing and the drive axle flanges, left an right side.

The gap is very small, about 1/16 of an inch or less in the straight ahead position, but there must be some, because turning the steering makes that gap slightly smaller.
For example a worn ball joints or the infamous offset ball joints make that gap disappear and the shaft rubs the housing.
Same happens if the brake dust shield is discarded because of rust.

Ps: the sound it makes is terrible, I had it once that way.

This is how it looks.

Also check that the shaft is centered inside the axle housing, if it looks like mine here - no bueno.

 

[RodMorris]

I will try replacing some u-joints. Cheaper than a transfer case, or even a transfer case rebuild. I did have to replace the right front brake caliper. It was sticking and burning the brakes.