12valve@heart

Need some diagnostic ideas. I'm on vacation near Colorado Springs and have started hearing/feeling a rumble (for lack of a better term) that disturbs me. I haven't been able to nail it down exactly but it seems to occur most frequently on deceleration at around 50mph. It's more pronounced when I'm in 4th gear but I think I can detect it in 5th and in 3rd as well as when coasting in neutral; just not near as pronounced. It almost feels like you're driving on a gravel road but when you accelerate, it seems to go away.

My first thought was a front wheel bearing so I checked those this morning, replaced one and packed the other and both are smooth but the rumble is still there. My next thing to check (after posting this) will be the carrier bearing but I'm looking for any ideas that might lead to the source of the problem. I still have another 2K miles to go towing a 35' travel trailer before I get home so I'd rather find it now then when it goes from rumble to BANG!!

Thanks in advance.

12valve@heart

More info - The carrier bearing has about 1/2" movement in the rubber from full pull down to full push up. I'm getting ready to drop the drive shaft to see if the bearing is at all rough. Also, the pinion has about 18-20* of slack but that's been there for years and the fluid level is up with no leaks. I also checked and the Getrag output nut is still in place. I'm running out of ideas for where to look.

big stinky

Its your rear... Get that fixed before it locks up on ya...

12valve@heart

Checked the carrier bearing and it seems smooth. Not sure where to look next.

FWIW, I've only noticed the "rumble" in the last couple of hundred miles and it occurs whether towing or running empty. Any thoughts?

12valve@heart

You're saying that the ring and pinion is making the rumble?

Don't think that's something that I can fix in the auto parts store parking lot.

dozer12216

If Ring / pinion were seriouslly failing the fluid would be black with sparkles of metal visible and would smell burnt.
Rear end would do at same speed in any gear!!!! Engine would do in any gear at same RPM. If you have verified u-joints and center carrier bearing, you might be looking at tranny. Check fluid in tranny. Good Luck

12valve@heart

Transmission has a slow steady drip because of sealant failure when I rebuilt it last year so it get's checked regularly. Just checked it again and it's still at the 5qt level. Hope it's not due for another rebuild already.

Pretty sure that it's not engine although it could be an accessory bearing or idler. Guess I can pull the belt and check.

Haven't "verified" the u-joints except to shake them to look for slop. No slop visible but it could still be some frozen or gaulded needles. Only thing it could be on the carrier bearing would be worn out mounting rubber allowing the drive shaft to whip but the rubber didn't seem that soft.

Could be the rear end since 50mph under deceleration is the speed at which it's most noticeable or it might be a rear wheel bearing. Spun the rear tires the other day and didn't feel any bearing problems but the pinion is obviously a potential issue. Next time that I take it out, I'll check the differential with my IR temp gun to see how hot it's running. Any idea what it should be when towing?

Guess if I can't nail it down, I'll just have to proceed with caution and hope that it get's me home or else gets worse so that I can fix it before it dies.

CaptainChrysler

I say it's probably the hanger bearing.

Mine does this same thing, has newer 'joints and a sloppy hanger bearing.
Was gonna do it too, but o'reilly's gave me the wrong one.

randyswelding

from my experiance goin to terra hute In for schieds diesel fest in august my dad crawled under to check my center bearin and it was fine but the pinion wasnt,needless to say i came home on a dana 60 dually rear axle!i snapped my pinion,well i found my problem the hard way.you didnt say how much you way unless i missed it mine comes in at around 11,000lbs on that trip.but try that center bearin its easy

cootz

x2 on the drive shaft U-joints. I've had the truck vibrate with tight U-joints before. Took them apart and the bearing (what's left) falls into your hand.

Spicers right through 5x-160.

big stinky

Sorry, misread your post... And didnt noticed you were an extra cab...
When you check the u-joints for slop, make sure the ebrake is on and its in neutral to take all the load off the driveshaft.

If its the rear, it could be the pinion bearing. If it has ANY play, its bad.

Tron

Seems like this just started and is more during braking from what I understand. Just a guess but could the tires be feathering a bit and causing noise during decel.

12valve@heart

Not during braking, during engine deceleration (vehicle pushing against the engine). I didn't see any abnormal tire wear on the front tires when I had them off this morning but I can check the rears.

Thanks for all the ideas. Maybe tomorrow will yield a solution.

cootz

Jay, did you ever find out what was causing your problems?

12valve@heart

Nope.

I know that I have several issues to resolve (fluid leak on the inside of the RR wheel, warped rotors, wobble/bounce at 30-35mph, pinion slack, to name a few) but I haven't identified that rumble yet. I noticed it more frequently when running empty last week than when towing this week so it may be intermittent or towing may dampen it to some extent. I've made it down to Santa Fe so I'm hoping that it will hold together till I get home and then I'll start going thru things one at a time and maybe will figure out where the rumble comes from.

By the way, I've noticed that when pulling hard in 4th, as the RPMs drop down close to 1500, I'm hearing a chuffing noise from the motor, almost like a exhaust manifold leak. At that point, boost has dropped from 15psi down to about 10psi so I don't think that it's related to the turbo but I don't hear it at any other time except when getting close to lugging in 4th. Thoughts on that one?