1997 2500 4X4 Strange Noise

[Seabee]

Okay guys,

I hate trying to diagnose under hood noises over the internet, so I apologize in advance for asking all of you to do the same thing! I am looking for ideas.

Very sporadically I will get a noise that sounds like a dry squealing bearing. It only seems to happen at highway speeds. It may hardly be noticeable, or more easily heard. It never lasts for more than a few seconds, at most.

I thought it was the left front wheel bearing. I went ahead and put the Spyntec hub conversion kit on it, as I did hearing a clicking noise in that bearing and I wanted to do the hub conversion for a while anyway. Great kit!!

I took the serpentine belt off and checked all of the usual suspects. Water pump, alternator, tensioner pulley and the A/C compressor pulley bearings. They all felt great and spun free. I did go ahead and put a new tensioner pulley on anyway, as I had one in my travel kit. I checked all of these items hot and cold.

I have topped up all of the fluids. I checked the fan clutch, but found nothing unusual there. I even checked the blower motor to make sure it wasn't the cause!

I checked the turbo out and it spins great. No strange marks on the impeller. There is just a very minute amount of side play in the shaft, but could only be felt by a fellow wrench turner. Maybe .001 to .002.

I don't believe that it is the throw out bearing, as it was new 5,000 miles ago and makes no noise when the pedal is depressed. The trans is a Standard Transmission rebuild with 5,000 miles on it.

My only suspect now is the power steering pump or vacuum pump. The fluid looks good in the pump. I flushed it about 15,000 miles ago.

Okay, what did I miss or what have any of you discovered in the past that might apply here? I appreciate any ideas.

Seabee

 

[savage54]

You still might look at the throw out bearing or in that area, my 97 ford had about 3000 miles on a new clutch and bearing, it started to make a small chirp noise ,it ended up being the pivot point for the clutch fork. So I put a little anti seize on the ball and the socket and it went away. I here you it drove me crazy trying to find that noise.

 

[Joe Mc]

Buddy of mine used to have an 01, 6spd 3500 and had a squealing noise we looked at everything (or at least we thought so) turned out to be u-joint on front diff prop shaft. Odd that the squeal seemed to be at the engine speed but we couldn't duplicate sound out of gear or at a stand still, only did it while going down the road, that u-joint was the bugger?

 

[Seabee]

Buddy of mine used to have an 01, 6spd 3500 and had a squealing noise we looked at everything (or at least we thought so) turned out to be u-joint on front diff prop shaft. Odd that the squeal seemed to be at the engine speed but we couldn't duplicate sound out of gear or at a stand still, only did it while going down the road, that u-joint was the bugger?

Thanks Joe. I thought about that, but the prop shaft doesn't spin unless it is in 4WD. I found a questionable u-joint in the drivers side axle when I did the hub conversion. It wouldn't have lived long in 4WD.

 

[petersonj]

I hate trying to diagnose under hood noises over the internet, so I apologize in advance for asking all of you to do the same thing! I am looking for ideas.

No need to apologize - you have provided excellent information for others to use to help diagnose your symptoms.

You said that you removed the serpentine belt and checked all of the different pulley bearings. When checking the AC compressor, you are only spinning the bearing that is in operation when the AC clutch is not engaged. It is possible that the noise could be coming from the compressor when it is engaged.

You can easily rule this out by driving the truck with the HVAC controls in the vent position, or any position that does not allow for the AC compressor to run. If the noise is still heard, then it is not the compressor. If the noise goes away, then you are on to something.

Just one more step in the process of elimination...

- John

 

[Mike B.]

Are you certain that the noise is coming from the front end? I had a similar issue trying to track down a squeal a couple years back on my 99 lwb truck. I turned out to be the carrier bearing on the rear prop shaft. It's sling ring had somehow worked it's way loose and was freewheeling around the shaft making all sorts of racket. It sounded very similar to an AC compressor clutch clanking around.

Mike

 

[Mike B.]

Thanks Joe. I thought about that, but the prop shaft doesn't spin unless it is in 4WD. I found a questionable u-joint in the drivers side axle when I did the hub conversion. It wouldn't have lived long in 4WD.

hmm Pretty sure the drivers side axle & the prop shaft spin all the time. Engaging 4x4 slides the locking collar that connects the axles and puts transfer case in gear. It's unloaded but the front shaft still spins.

 

[petersonj]

hmm Pretty sure the drivers side axle & the prop shaft spin all the time.

When two-wheel drive is selected and the CAD (center axle disconnect) is disengaged, both front axle shafts being driven by the tires will continue to rotate, but the propeller shaft may come to a stop. Under these conditions the right axle shaft including the right side the u-joint is disconnected from the axle stub shaft coming from the differential. The left axle shaft continues to drive the ring gear via the left differential side gear. From this point the rotation generated by the left tire could be directed to the propeller shaft via the ring and pinion gear and / or directed to the right side axle stub shaft via the differential gears. Probably the energy will follow the path of least resistance.

So, the propeller shaft may spin, but without much energy. If a u-joint in the propeller shaft was causing enough resistance to make noise, then the propeller shaft would probably just stop spinning and all of the energy from the rotating left front tire would be diverted to the right axle stub shaft.

Just another opinion, not necessarily the right one.

- John

 

[Seabee]

No need to apologize - you have provided excellent information for others to use to help diagnose your symptoms.

You said that you removed the serpentine belt and checked all of the different pulley bearings. When checking the AC compressor, you are only spinning the bearing that is in operation when the AC clutch is not engaged. It is possible that the noise could be coming from the compressor when it is engaged.

You can easily rule this out by driving the truck with the HVAC controls in the vent position, or any position that does not allow for the AC compressor to run. If the noise is still heard, then it is not the compressor. If the noise goes away, then you are on to something.

Just one more step in the process of elimination...

- John

I only have been running with heat or vent. It's still pretty cold here!

 

[Seabee]

Are you certain that the noise is coming from the front end? I had a similar issue trying to track down a squeal a couple years back on my 99 lwb truck. I turned out to be the carrier bearing on the rear prop shaft. It's sling ring had somehow worked it's way loose and was freewheeling around the shaft making all sorts of racket. It sounded very similar to an AC compressor clutch clanking around.

Mike

Mine is much more like a squealing dry bearing. I just rebuilt the entire rear driveshaft assembly. That said, maybe I got a bad carrier bearing?!

 

[Seabee]

When two-wheel drive is selected and the CAD (center axle disconnect) is disengaged, both front axle shafts being driven by the tires will continue to rotate, but the propeller shaft may come to a stop. Under these conditions the right axle shaft including the right side the u-joint is disconnected from the axle stub shaft coming from the differential. The left axle shaft continues to drive the ring gear via the left differential side gear. From this point the rotation generated by the left tire could be directed to the propeller shaft via the ring and pinion gear and / or directed to the right side axle stub shaft via the differential gears. Probably the energy will follow the path of least resistance.

So, the propeller shaft may spin, but without much energy. If a u-joint in the propeller shaft was causing enough resistance to make noise, then the propeller shaft would probably just stop spinning and all of the energy from the rotating left front tire would be diverted to the right axle stub shaft.

Just another opinion, not necessarily the right one.

- John

You are correct John. Regardless, I now have a $1500.00 set of locking hubs, so nothing is spinning now!

 

[KATOOM]

Not only is it next to impossible to diagnose such noises...but then for those noises to only happen for random moments means you'll likely only find the culprit when whatever it is decides to go full failure.

I'd say try to capture the noise on video but it sounds like thats not going to be possible either.

You've seemingly covered everything which could squeak too except for the HVAC fan. So my only suggestion would be that whenever the squeaking noise happens, do everything you can as quickly as you can to see what the noise follows. Meaning, is it following driveline speeds, engine rpm speeds, specific transmission gear speeds, clutch assembly speeds, etc... That may help narrow down the search.

 

[Seabee]

Okay, Mike B is the winner (I hope)! Turns out the shield for the new carrier bearing had come loose from it's mounting and was flopping around on the driveshaft. I secured it and went for a long drive. No noises. I don't want to get too excited, but I think it was the cause.