What opinion do you have?

[rupert's]

Do you think I should worry about this watch?
It only sounds when I have the 4x4 and when the car is working hard it makes a lot of noise I notice a small bump in acceleration...

https://youtu.be/IVXnjm9sjUU

All the best

[rickf]

Since it happens on one rotation of the axle every time I am going to say it is a chipped tooth on the spider gears. There is a replacement kit for that. Here it is from Army Jeep Parts but all you need to do is Google that NSN number and you will find it in other places also. https://www.armyjeepparts.com/p-3115-m1 ... -1339.aspx
Here is a tutorial on how to rebuild the differential, it is not hard to do and as long as the bearings are good you will not need to do anything but replace the bad parts.
https://www.g838.org/viewtopic.php?f=3&t=4863

[rupert's]

Looks like this will be my next purchase... I'm going to remove the differential tomorrow, and look for this split tooth.
This car always keeps me entertained.

Thank you Rick

[rickf]

Note that I said the spider gear and not the ring gear. I am not sure if you will be able to see the spider gears through the fill hole. If it were the ring gear making the noise it would have done so every 4.6 turns of the pinion gear. I was counting and the pinion was not consistent so the spiders were rotating the other tire backwards. but I would bet on either that left side gear or one of the spiders. That is usually caused by having one tire on a hard surface and spinning the other tire until it hits something hard, like a rock or the edge of the pavement. The sudden shock will break spiders on open differentials every time.

[rupert's]

Today I have taken it out, the crown seems to be fine, I need an extractor to remove the bearing and see the internal parts. This week I'll take the bearing out to see what's wrong in there...
On the other hand, this bearing has a little rust, and the race has a little too but very little... Should I change it? Cheers!

[rickf]

That differential looks like it spent some time filled with water, or had water in it. Those bearings definitely need to be replaced. And the races with them. The axle splines do not look very good either but they will come with the kit I mentioned before. You will not need a puller to get to the spider gears, if you turn that carrier over there are bolts on the other side inside the ring gears ring that hold the other side of the carrier axle and spider assembly on. Bend out the locks and remove those bolts to get to the axle stubs and spider gears. I think this is where the problem is. You will need to get into the -34 manual to get all the torque specs to put all the bolts back in. I don't have them off the top of my head. If that double sided race for the pinion bearing is bad you may have trouble finding it or you may not. I have seen them for everywhere from 20.00 US to 200.00 US! Don't ask why the difference in price, I have no idea. I was going to rebuild the dozen differentials I have here but that one part is what holds me up.

[m3a1]

I'd also be interested to know what your gear oil looked like. I don't think you've mentioned it.

[rupert's]

The gearbox oil is fine, the differential oil is the one that turns bad, brown, I change it every few months, but it always turns brown again. This is because before it had water inside and now no matter how much I change the oil (valvulin) it always turns brown again.
Since I have it open, I am going to clean it well and I am going to change this bearing that has a little rust, I hope that way it will stop giving me problems.
Let's see if I have time and finish disassembling it to see the spiders.

[Lou]

It looks like you have play between the splined axle shaft and the carrier housing (ask how I know this). See if you can wiggle the axle shaft that is sticking out of the carrier, bet you can. That would make that noise as the axle shaft U joints exert some lateral force as they rotate and moves the axle shaft around in the carrier.

[Lou]

This thread is probably as good a place as any to post a similar situation. I changed a diff because of this issue earlier this year. https://www.youtube.com/watch?v=UZcBMSSeyIs

Well the new one only went 300 miles and failed again with excessive ring and pinion play. I will take the blame, it was my own fault but here is the back story.

Had 2 brand new NOS diffs in the foamed box. Both of these went under water during hurricane Sandy (Salt Water). The one that just went 300 miles was the one that was under water. I opened both the drain and fill plugs and looked inside and found no water or any rust that I could see. However the diff appeared stuck and had to use a little force to get it unstuck. Did not hear any bearing noise so assumed the diff was ok. Filled it with a quart of gear oil and installed it.

So the diff started to get loud after 300 miles, and found the drive shaft could be rotated half a turn each way before the axle shaft turned. Could also push one axle shaft on one side and the opposite one would push out.

Long story short. There was little rust marks on the carrier bearings, just like you have. In my case though, apparently my bearings were rusted tight to the bearing race. So in use the bearing races spun in the housing and ruined the diff housing. That is why it had excessive play, the bearing race wore into the bore of the case. The only thing I salvaged out of that diff was the carrier which appeared fine no play or rust in the spiders. May put that carrier in the case from the video above.

To add insult to injury, took the other brand new diff apart. Found plenty of salt water inside. After 10 years of sitting with salt water inside there was nothing salvageable inside and just took it to the junkyard and sold it for scrap.

So 2 lessons learned. The foam used in those boxes is not waterproof, the water got inside the box. Lesson 2, those axle seals suck and easily let water inside the diff. Cannot even count how many times the rear diffs have had oil changes because of moisture in the oil. Never found in the front diff, always the rear. Always thought water came in the vent and changed them, but learned it is the crap seals. And we never ever go through water up to the axle hub.

It is crazy, owned all manner of off road vehicles. Never had water get through axle seals. Jeeps, VW’s woods cars..... never water in the diff. And here is a vehicle that is suppose to be designed to go underwater and it cannot even ford a foot of water without water getting into the diff.

We love the mutt but after 4 rear diffs over 18 years and 10,000 miles have to admit to getting tired of it. Keep looking at used Rubicon's and thinking maybe that’s the way we should have went.

[rickf]

Louie, One thing you have to consider is that in use those diffs get very hot and when you put them in water they cool off fast and the air inside contracts and pulls in water. The military manuals tell you that after fording all of the fluids need to be changed, not checked but changed. They know the seals are going to leak. On my CJ I have my stock vents eliminated so there is no restriction at all and in place of those vents are hose nipples with lines leading up to the top of the cowl and formed into a U shape facing down. This way air moves freely in and out of the differentials, transfer case and transmission so that there is never a pressure differential to pull water in. I never got water in any of those parts in the 20 years after doing that. Wheel bearings are a given, they are going to get wet, I use lithium boat axle grease on them. But keep in mind this is on a vehicle that I plan on dunking on a regular basis. With the 151 if I go off road like trail rides in Virginia I will come home and drain all of the fluids and refill with fresh. Regardless of whether I think I might have gotten water in or not.
And I just have to add in this little jab, you say you never go through water above the hubs? Left picture of your avatar! SNAGGED.

[rickf]

These differentials, and transmissions will get a LOT of water in them just from sitting if you live in an area with a lot of moisture in the air and warm days and cool nights. Just normal condensation. It is even worse if the unit has been sitting out of the vehicle on a skid outside in the sun. Hot,cold hot,cold.

[Lou]

And I just have to add in this little jab, you say you never go through water above the hubs? Left picture of your avatar! SNAGGED.

Rick,
Yes, should rephrase what I said. The Mutt Never goes into water over 1 foot deep anymore. In the first year we owned it changed countless u joints, wheel bearings, a diff, hell even lost ball joints. Did not own a set of TM's when we first purchased the Mutt. Then learned the part you explained, change all fluids at every underwater event.

Remember reading that fording was an act of war and should not be done unless it was the only way to carry out a mission. So yea, we learned our lessons and just make u turns now when we come across giant water holes in the woods, and there are plenty of them now.

You may not be aware, NJDEP wants to institute a permit system to drive the trails in the woods! Been active trying to prevent this from occurring. There are facebook groups to try and stop this as well (I know you hate Facebook as I do). However there is a petition and you may want to sign it here https://www.change.org/p/no-permits-no- ... g6m47vSjqk

Would encourage off road folks from other States to sign it as well. Because if NJ pulls this off, you can be sure other States will follow the money trail as well!

[rupert's]

This thread is probably as good a place as any to post a similar situation. I changed a diff because of this issue earlier this year. https://www.youtube.com/watch?v=UZcBMSSeyIs

Well the new one only went 300 miles and failed again with excessive ring and pinion play. I will take the blame, it was my own fault but here is the back story.

Had 2 brand new NOS diffs in the foamed box. Both of these went under water during hurricane Sandy (Salt Water). The one that just went 300 miles was the one that was under water. I opened both the drain and fill plugs and looked inside and found no water or any rust that I could see. However the diff appeared stuck and had to use a little force to get it unstuck. Did not hear any bearing noise so assumed the diff was ok. Filled it with a quart of gear oil and installed it.

So the diff started to get loud after 300 miles, and found the drive shaft could be rotated half a turn each way before the axle shaft turned. Could also push one axle shaft on one side and the opposite one would push out.

Long story short. There was little rust marks on the carrier bearings, just like you have. In my case though, apparently my bearings were rusted tight to the bearing race. So in use the bearing races spun in the housing and ruined the diff housing. That is why it had excessive play, the bearing race wore into the bore of the case. The only thing I salvaged out of that diff was the carrier which appeared fine no play or rust in the spiders. May put that carrier in the case from the video above.

To add insult to injury, took the other brand new diff apart. Found plenty of salt water inside. After 10 years of sitting with salt water inside there was nothing salvageable inside and just took it to the junkyard and sold it for scrap.

So 2 lessons learned. The foam used in those boxes is not waterproof, the water got inside the box. Lesson 2, those axle seals suck and easily let water inside the diff. Cannot even count how many times the rear diffs have had oil changes because of moisture in the oil. Never found in the front diff, always the rear. Always thought water came in the vent and changed them, but learned it is the crap seals. And we never ever go through water up to the axle hub.

It is crazy, owned all manner of off road vehicles. Never had water get through axle seals. Jeeps, VW’s woods cars..... never water in the diff. And here is a vehicle that is suppose to be designed to go underwater and it cannot even ford a foot of water without water getting into the diff.

We love the mutt but after 4 rear diffs over 18 years and 10,000 miles have to admit to getting tired of it. Keep looking at used Rubicon's and thinking maybe that’s the way we should have went.

Greetings Lou, Thank you for your response and for sharing your experience, I have seen the video and I think I have a bit of that problem in the rear differential, but that is a war that will come later. In addition, I changed a bearing in the rear differential and I have not done the adjustment well and it has a lot of play in the turn. But as I said before, these problems are for another day, now I want to repair this front differential, put it back and then check the rear.

In my case, the bearings move freely, and the races do not seem to have been rotating on the casing, this makes me think that the problem is not the wear of the casing due to the bearing being stuck. I only have one bearing with a little rust, the others seem to be in good condition. I need to have a little time to finish opening the differential and see the spiders, the work leaves me little free time and I am also preparing the rear support to put the antenna. I don't have time for everything but I'm sure before Sunday I'll have seen the inner gears.

I have spent several days translating into Spanish the differential assembly maintenance manual (TM 9-2320-218-34-1 Chapter 11) if anyone needs it I can send it to them.
I keep you informed with the news, thank you very much for your help!

[Horst]

I can certainly confirm that the foamed-in parts are not protected from water. Found this out when I got a replacement engine delivered in the foam to only find out that it was rusted beyond any repair...