Odd noises and other things, help?

[Power Wagon]

I've got a rather loud howl that becomes pronounced between 30 and 45 mph. If you are very gently accelerating it's loud both inside and outside the truck. If you are driving over wavy or rough road, the howl is modulated by the bumps. It gets louder and softer seemingly with the motion of the truck. At higher or lower speeds you can hear some noise, but not really all that noticeable. The pitch is precisely matched to speed.



Possibly related: This is most noticeable while slowing to a stop, at say, a stop sign. At around 15 mph or so, if you are going downhill or are braking, a growl that is not loud, but you can feel. The whole truck rumbles. It is not brakes, because you can let off the brakes, and it continues to make it until it stops, with the frequency dropping until you stop moving. If you let the truck coast, without braking, it never makes the noise. If you just tap the brakes, it starts instantly until the truck is stopped or you accelerate above the speed it's noticeable. It seems to just fade away if you accelerate.



Theories:



It's a driveshaft carrier bearing. End thrust caused by deceleration makes the bearing growl.



Differential problems - loose bearings on the pinion, causing it to shift in relationship to the ring gear, causing howl and growl when driving or being driven.



If you've had either, or have had a noise like these... I need some input, as I need to get anything it needs done ASAP.

 

[Steve Campbell]

Mark, this is going to sound unrelated, but what do the motor mounts look like? I see your new baby is a 1st gen. Maybe there is enought/age miles on the old ones that metal parts are getting close together. The other thing to check IMO would be the brakes after reading your second paragraph. A good clean/lube/adjust job will make a difference on almost any truck.

 

[Power Wagon]

Originally posted by Steve Campbell

Mark, this is going to sound unrelated, but what do the motor mounts look like? I see your new baby is a 1st gen. Maybe there is enought/age miles on the old ones that metal parts are getting close together. The other thing to check IMO would be the brakes after reading your second paragraph. A good clean/lube/adjust job will make a difference on almost any truck.

Hmmm... . Hadn't thought about that...



But if it were engine, it would make noise in relationship to the engine speed, which it does not - it's clearly road speed, not engine, because it slows down and stops completely when the truck does. But I will check the mounts. It does seem like the engine resonates in the interior unusually loud every now and then and that might be it.

 

[hdm48]

OK. you said that if you 'tap' the brakes it starts making the noise. Well, that sounds a lot like the return springs in the rear brakes. And I bet the shoes back there are glazed. One other thing. this might not cure the problem but it could be a cause. whoever adjusted the parking brake cable might have done it befor making sure the brakes were properly adjusted causing the shoes to be out of their seat/ rest possition. When I first got my truck the peddle was spongy. after going through everything with a microscope I found this to be the problem all along. It ruined the shoes and over heated the springs to the point they wouldn't pull the shoes away from the drum.



good luck dave

 

[Grey Wolf]

Mark,



Fortunately I don't have this problem but per your description I would say you should take a look at the differential. If anything at least it will get a fluid change! How was the trip home?

 

[Paychk]

You might want to check the phasing of the u-joints, this usually applies to trucks with a slip joint right behind the carrier bearing, if the slip joint was disassembled and not returned to the poisition where all joints are straight up and down it can cause a growl. Put your truck in neutral and roll the wheels till any one of the u-joints is straight up and down. Hold it there and look at the others they should also be straight, separate the slip joint and adjust till alignment is set.



Alan

 

[Tim1]

Hey Mark, Jack the rear end up and put on jack stands, then have the wife turn the differential over and with a large screwdriver, listen on the plastic end to the carrier bearings and also the wheel bearings, If it growling, you will certainly here it. If the problem ends up being in the differential, e-mail me and I'll head you in the right direction in Portland. Been there done this and 650. 00 later, new rear end. Hope this helped. Tim

 

[RDBuck]

Howl,growel and other strange noises.

Had much the same symptoms. Required a complete rear-end rebuild to the tune of $1400. All noises and vibrations are gone. Was a little surprised that this rear-end wore out at 120,000. Never had to rebuild a rear unit in any other truck I have ever owned and there have been too many to list.

 

[Power Wagon]

I've decided the low speed growl is a combination of things, but mostly clutch chatter for the limited slip. It pretty much does it when turning. I'd never made the connection before today, when I drove it a lot in town. The engine pulses at idle seem to cause the LS to chatter almost in time with them while turning. It's even more pronounced with the brakes on because there's torque against the tires and torque pulses from the engine.



I got a carrier bearing today, to put on to see if that ends the howl. If not, then I gotta have bearings put in the differential. Local shop gave me a figure of about $300 to rebuild it using just a bearing, seal, and gasket kit. If the ring and pinion are bad, add another 300. To rebuild the LS system, add another 300...



Not as bad as it could be, I guess.