I think I have a big front diff problem…

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Tim Herald

Tim Herald

Joined
Nov 25, 2025
Threads
28
Messages
300
Location
Lexington, KY
Took my ‘92 on a short road trip last weekend and drove it about 1.5 hours down the interstate each way. After that, with acceleration it started a high pitched whining. Everything I read said bearings or gears in front diff. Went to change diff fluid today just to try knowing I was going to have to rebuild or replace most likely. Drain plug didn’t want to come out, and I couldn’t afford to mess it up because I’ll be hunting out of my truck almost daily for a month.

So just decided to top off the gear oil until after season and then address it properly. Well it must have been dry as it took almost 3 quarts. After driving it 5 miles and parking it, the oil is coming out of passenger side axle seal big time.

So totally under the gun and can’t do without the truck - so how bad is it to run it ? PO must have known and just left it as is because there was a front axle rebuild kit that came in the box of parts that came with truck. I have put about 2500 miles on it in past 4/5 months but I guess high speed sustained put it over the top.

I’ll have it all rebuilt or replaced but need to wait till May/summer if at all possible. Thoughts?

And take into consideration that on a scale of 1-100 vehicle/mechanical knowledge, I am a 2! Thanks !

IMG_5366.webp
 
Without knowing much I’d say that you need to pull the R axle shaft and replace the axle seal.
Do you have a FSM? If not it’s all on line. It’s an easy job that will only take you 5 hours based on your rating. You will be happy and smarter once you complete the job. It won’t stop leaking on its own!
 
devo said:
Without knowing much I’d say that you need to pull the R axle shaft and replace the axle seal.
Do you have a FSM? If not it’s all on line. It’s an easy job that will only take you 5 hours based on your rating. You will be happy and smarter once you complete the job. It won’t stop leaking on its own!
Click to expand...
Yup know it won’t quit on its own. Do have FSM. My son is probably a 50 - but just not sure about timing. I guess we gotta get in there. It’s a mess.
 
Do some reading here too on knuckle rebuilds for others experiences taking care of this. It's not super difficult but it's messy, and on your scale of 1/100, it's above a 2

Search for thread titled "check yer nuts"


Also, I would 100% recommend you watch this video



I haven't watched this one, but Otramm's YouTube tutorials that I have used have been a fantastic resource
 
Also, work on getting the drain plug out so you can drain the oil,
See if there's any metallic debris in the oil.

If you ran it dry, at the very least, refill the oil, and drain/ refill again after a few hundred miles, try to get rid of any gunk out of the housing, and look for metal debris tech time.

You might be lucky and done no major harm or bearings and gears could be toast
 
Thanks folks. I am thinking what I may do is try to take it to my local shop and have them rebuild axles and knuckles for now. Then it will hold gear oil at least. The oil all leaked out overnight last night. I have the axle rebuild kit already. I’ll have them inspect the diff and see if bearings and or gears are damaged. If so- I’ll have to plan to have that rebuilt in a month or so. Right now I need the truck functional asap as our turkey season starts next Saturday and runs 3 weeks and I go almost every day and that’s a main purpose for this truck.
I am all ears for info and opinions.
 
I think this is a situation where it's going to be very involved, requiring a rebuilt or used diff, along with full knuckle rebuild. If the knuckles are being rebuilt, or even if just slapping a band aid on it (replacing inner axle seals) you're in deep enough to pull and swap out the diff. Dry gears and bearing don't hold up well to extended driving.
 
Tim Herald said:
Thanks folks. I am thinking what I may do is try to take it to my local shop and have them rebuild axles and knuckles for now. Then it will hold gear oil at least. The oil all leaked out overnight last night. I have the axle rebuild kit already. I’ll have them inspect the diff and see if bearings and or gears are damaged. If so- I’ll have to plan to have that rebuilt in a month or so. Right now I need the truck functional asap as our turkey season starts next Saturday and runs 3 weeks and I go almost every day and that’s a main purpose for this truck.
I am all ears for info and opinions.
Click to expand...
As a fellow hunter and with due respect...
I wouldn't drive it until it is back to 100%
Or, hope you get a turkey on opening morning
 
2 things I don't think have been mentioned yet.

1) the sustained driving causing the oil to puke is almost certainly explained by a clogged axle breather/ vent hose. This is common and when things heat (ie during an extended drive) the oil expands filling the volume of the axle housing. When the vent is clogged the pressure builds and forces oil out the seals. You could try cleaning the vent (5 min Google search and another 5 under the vehicle) and topping off again and see how things are then. Obviously you're due for a rebuild but that could be making things look worse then they seem.

2) if the truck is any use to you in 2wd it's a fairly simple and free thing to pull the front driveshaft and flanges and lock the center diff in high. This turns your 4wd/awd into a rear wheel drive with all of the rotating bits in the front end not rotating. You can drive like this indefinitely until you have the time and/or funds to rebuild the axle. If you're going to run like this for a while it's a good idea to swap your drive flanges for unsplined ones. I can send you the stl's for this if you have access to a 3d printer
 
60 toy ota said:
2 things I don't think have been mentioned yet.

1) the sustained driving causing the oil to puke is almost certainly explained by a clogged axle breather/ vent hose. This is common and when things heat (ie during an extended drive) the oil expands filling the volume of the axle housing. When the vent is clogged the pressure builds and forces oil out the seals. You could try cleaning the vent (5 min Google search and another 5 under the vehicle) and topping off again and see how things are then. Obviously you're due for a rebuild but that could be making things look worse then they seem.

2) if the truck is any use to you in 2wd it's a fairly simple and free thing to pull the front driveshaft and flanges and lock the center diff in high. This turns your 4wd/awd into a rear wheel drive with all of the rotating bits in the front end not rotating. You can drive like this indefinitely until you have the time and/or funds to rebuild the axle. If you're going to run like this for a while it's a good idea to swap your drive flanges for unsplined ones. I can send you the stl's for this if you have access to a 3d printer
Click to expand...
So I had never had any leakage from the axles until I filled diff I am assuming I have been driving it basically dry since I got it. When I filled the diff thinking I was topping it off and it took almost 3 quarts, is the first time I had ever had anything leak out - so either I am wrong or totally amazed I have been driving it like that for 4 months since I bought it.
 
Professional diagnosis was need inner axle seals and knuckle rebuild on both sides. Optimistically thinking that the diff might be ok. They feel the bearings will need to be redone in the future but hopefully not a full rebuild/replacement. And my local guys at Commonwealth 4x4 are doing me a solid and having it finished by end of week so I will have for Turkey season Saturday.
 
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