M923A2 horrible loud noise coming from the differential or transfer case - 5-Ton

[Suprman]

The front driveshaft has a slip collar there should be no play in this if there is then it needs to be rebuilt. Any driveshaft shop should be able to do it. I have found when things are slightly out of balance they can vibrate and make noises but only at a certain speed or rpm.

 

[madcroc1]

Attached is an audio clip of noise

If you listen to this audio clip you will hear it.
It sounds like the recoil spring on a lawn mower pull start busting but louder...
Try to ignore the wind noise ...

My speed was about 15-20 mph. If i Accelerate faster the noise is much louder and becomes sustained ..... The noise was coming from the middle of the underside of the truck so I doubt it was the fan clutch.

 

[two.fiveM35]

That's not the noise mine makes, not yet at least.

 

[Stevepala]

I had a drive shaft universal that made similar noises. Pulled the caps and the needles were broken.

 

[Farmallmilitary]

I had a problem on my truck that it would sometimes make a huge clunking noise and then stop. I traced it to the drive shaft parking brake. I took it apart and there were broken springs that were loose and they would rub and jam up. Replacing them fixed the problem and it hasnt done it since.

 

[madcroc1]

View attachment Memo.wmvCan anyone listen to the audio file and help me diagnose the problem? Have any of you 5-ton-ners heard that noise ?

 

[Suprman]

It sounds like an am radio with bad reception

 

[Andyrv6av8r]

The noise seems to come on strong when accelerating and "kind of" goes away or gets quieter when coasting or slowing. Sometime the noise is not there at all, and then all of the sudden it kicks in ... It certainty is intermittent.

I listened and my " New to me " 923 was making the same noise and had the same characteristics you stated above. It was a 2008 RRAD rebuild. Beautiful truck.

A quick back story. I won a 923 recently that I picked up and drove home. As soon as I left the National Guard Base and the truck shifted to 5th gear, I heard the same noises as above. It only did it going up hills. It always went away on level ground and down hills. I just knew I had gotten a truck with a bad transmission or transfer case. Drove it over a 100 miles home without any problems. Just out of curiosity the next day I jacked the front axle up and checked to see if it was engaging like it was supposed to. Low and behold to my satisfaction, it wasn't. As I suspected, the air lines on the Low Engage air switch on the transfer case were plumbed incorrectly. The truck was in 6 wheel drive all of the time. After correctly plumbing the switch so that the front axle wasn't engaged all of the time, the noise went away. I suggest you check that. Just my 2 cents worth.

 

[ranchhopper]

Thats not what my two sound like.

 

[Hoefler]

I recently installed new rebuilt mk18 on the back of my mk48. Took her out on its maiden drive and about a mile down the road, a similar noise erupted- very loud and got loader the faster I went. After lots of stop, start, check this and that, I found the problem.
the drive Shasta for the mk18 passes through a hanger bearing. The drive shaft has a collar on it- thin metal, basically a splash shield. The outer edge of this shield, about 3 inch diameter, was rubbing on a portion of hanger. Two ways to correct it. One is to loosen hanger mount and push forward with hammer or simply bend back the splash shield with a screw driver. I did the latter and problem solved.
check your splash shield for rubbing/missing paint. If so, it's an easy fix.
pete

 

[ranchhopper]

Thats what I figured was causing the noise on my trucks too.

 

[Beerslayer]

An IR temp gun is good for finding hot spots. You can compare all the same areas on both axles.

Great idea. This reminds me, I need to check the operating temperatures of all my gearboxes, differentials, and universal joints, and note them in the log book for future reference. That has saved me before on my first deuce.

Mine is intermittent and seems to be related to bumps in the road. The noise starts instantly and stops instantly, kind of like a compressor kicking on and off,it has no pattern.

My first M923 made a similar racket and I first heard it right after leaving JBLM the day I picked it up. Scared the heck out of me. I eventually traced it to several worn bolts that wouldn't tighten up. I replaced them and the noise went away.

I listened to the WMV file, it sounds like gears or metal crunching. I had an old dozer that did that exact thing when a bunch of the gear teeth in the transmission got broken off.

 

[madcroc1]

Horrible Sound can't find it..

Here is a better audio clip of the noise. You can hear it comes on more when accelerating. My speed was only about 25 mph when the noise kicks in.. It seems to kick in when accelerating.. I also checked the temperature of all major components with an IR meter, after a long ride, and I don't see anything out of whack.

I checked the transfer case, the differentials, and the axles, all oil, lube, grease are clean and free of any debris dirt or chunks..


View attachment M923A2_Sound.wmv


Any other suggestions ? I'm off to get a GoPro Camera and perhaps that may help me locate the exact location of the noise..

 

[ranchhopper]

Did you try driving it in low range to see if it does the same thing.

 

[Hoefler]

Sounds familiar to me. Have mentioned my deal earlier in this thread. Mine was on an MK48/18. The culprit was on a hanger bearing. There is a clip of metal that holds in and locates the rubber in the hanger. As the drive shaft passes through, there is a shield made of light weight metal. This metal shield is located on both sides of the hanger bearing. My shield was coming in contact with the metal clip that holds the rubber in the hanger.
The noise you have recorded sounds just like what I experienced-almost like a roller bearing that is seizing.
Given yours happens when you accelerate, it may be due to rear axel pushing truck and drive shaft forward a bit. Look on the leading edge of your drive shafting and see if there is any fresh marks on anything.
Pete

 

[jdknech]

check the heat sheld under the cab thats over the exhaust... mine was rubbing the exhaust and making the same noise..

 

[Hoefler]

I took this photo of my drive shaft hanger this past weekend. Note the scrape mounts on what I call the shield. It was rubbing on the hanger bearing mount-a little tab. I simply have bent it out to clear.
Hope this helps.
Pete

 

[madcroc1]

thanks for the photos. What kind of truck is that ? My truck doesn't have a hanger like that. I don't see any hangers. The truck is a M923A2. I'll send over the photo shortly. Still cant seem to find the culprit to that noise..

 

[madcroc1]

Here are some photos of the underside

These are some pictures of my under carriage.

 

[dburt]

Sometimes a driveline u-joint will feel tight and look good, but have worn needle bearings that will rumble or growl only at certain speeds and under certain loads. A driveline center carrier bearing will often make the same noise when failing, and only under acceleration or certain speeds where the bearings start a harmonic vibration. Or, it could be that some of the bearings in the transmission or the transfer case are getting rough, and when 'loaded' under acceleration will growl, but smooth out under different loads or speeds. Let's hope it is just a shield rubbing on the exhaust or something simple and inexpensive to fix!