Front differential fluid leak

[Dogdoc90]

I’ve had a slow leak of transmission fluid at the junction of the front driveshaft with the transfer case that’s been slow enough to ignore. Yesterday a significant leak developed at the other end of the front shaft at the front differential. I’m assuming I need to drop the shaft and replace some seals but could use some advice. Never dealt with this before and not sure what I’ll find or where to get parts. Thanks

 

[chbrow10]

A few things to consider first.
- have you recently refilled the differential fluid? It may be possible that you over filled it (hard to do but possible), or that you used a thinner weight oil than the spec.
- same question for the transfer box.
- have you recently drive through deep water? it is possible that your diff vents or axle seals allowed some water to pass and that know you have water in your diff, causing it to be an "over filled" situation.

Second, the bottom photo looks like a pinion seal leak to me. The method of replacement of that seal needs to be studied in advance, as the you will need to remove the nut that provides the correct backlash. There is a method that is covered in the factory service manual that the DIY'r can do. There are some gear purists that say the axles need to be removed and the breakaway torque measured so it can be restored. Indeed, this is the method described in my dodge 3500 FSM. Study up and see what you are comfortable with

Third, there isn't enough for me to go on regarding the aft u-joint at the transfer box. The oil looks good, new maybe? There is a seal back there that should be not hard to replace, but there is a second seal as well. Google up a split case rebuild videos to see the seals that I am talking about.

You will unbolt at the front diff, then slide the aft yoke out of the transfer case, that has a slip joint over a splined male end. This allows the shaft to move as the suspension travels on the front axle. I like to mark everything (shaft, both yokes, diff/transfer box) and make sure it goes back on those marks for vibration purposes.

Not a bad idea to check your u-joints while you have it out to work on the seal.

Hope this helps.

 

[Dogdoc90]

A few things to consider first.
- have you recently refilled the differential fluid? It may be possible that you over filled it (hard to do but possible), or that you used a thinner weight oil than the spec.
- same question for the transfer box.
- have you recently drive through deep water? it is possible that your diff vents or axle seals allowed some water to pass and that know you have water in your diff, causing it to be an "over filled" situation.

Second, the bottom photo looks like a pinion seal leak to me. The method of replacement of that seal needs to be studied in advance, as the you will need to remove the nut that provides the correct backlash. There is a method that is covered in the factory service manual that the DIY'r can do. There are some gear purists that say the axles need to be removed and the breakaway torque measured so it can be restored. Indeed, this is the method described in my dodge 3500 FSM. Study up and see what you are comfortable with

Third, there isn't enough for me to go on regarding the aft u-joint at the transfer box. The oil looks good, new maybe? There is a seal back there that should be not hard to replace, but there is a second seal as well. Google up a split case rebuild videos to see the seals that I am talking about.

You will unbolt at the front diff, then slide the aft yoke out of the transfer case, that has a slip joint over a splined male end. This allows the shaft to move as the suspension travels on the front axle. I like to mark everything (shaft, both yokes, diff/transfer box) and make sure it goes back on those marks for vibration purposes.

Not a bad idea to check your u-joints while you have it out to work on the seal.

Hope this helps.

Thanks. May be above my pay grade but it’s a good start.

 

[scrapdaddy]

That dust cover and driveshaft look to be new, has anyone been working on it lately? Maybe they could steer you in the right direction.

 

[Dogdoc90]

That dust cover and driveshaft look to be new, has anyone been working on it lately? Maybe they could steer you in the right direction.

Yeah it’s fairly new when the PO switched out the original F1 and 3 speed tranny for a 79 F2 engine and 5 speed out of an FJ 60

 

[J Mack]

I’ve had a slow leak of transmission fluid at the junction of the front driveshaft with the transfer case

What is your mechanical ability?

These issues could be as easy as removing your yokes and sealing the splines to new bearings and seals, an oil leak is literally a “can of worms” and without the knowledge to address to root cause you could spend lots of $$$ and time chasing your tail.

If you’re not comfortable removing parts like third members or transfer cases it might be best to take it to a good cruiser mechanic in your area and let them give it a quick look over.

Just FYI: I’ve had an oil leak on my rear diff yoke three times and all three have been something different, some minor and some major.

 

[Dogdoc90]

What is your mechanical ability?

These issues could be as easy as removing your yokes and sealing the splines to new bearings and seals, an oil leak is literally a “can of worms” and without the knowledge to address to root cause you could spend lots of $$$ and time chasing your tail.

If you’re not comfortable removing parts like third members or transfer cases it might be best to take it to a good cruiser mechanic in your area and let them give it a quick look over.

Just FYI: I’ve had an oil leak on my rear diff yoke three times and all three have been something different, some minor and some major.

Good advice. It’s a bit out of my league and I’m having it looked at by a mechanic this week. Thanks

 

[PabloCruise]

Yeah it’s fairly new when the PO switched out the original F1 and 3 speed tranny for a 79 F2 engine and 5 speed out of an FJ 60

Wait, wait, wait! You have a 5 speed out of a 60 in there?

Could you post pics of where the shifter comes out, relative to your front seat(s)? Thank you!

Another Oregon Pig!!!

Dog doc - are you a DVM?

We need more pics of your Pig!!! We like pics...

 

[Dogdoc90]

Sorry about the typo, it’s a 4 speed. Figured out my suspected front diff leak; I recently replaced the oil pressure sender (another thread) and didn’t tighten it up well. Oil was leaking onto the yoke of the front drive shaft and I thought it was transmission fluid. Solved that but still can’t get oil pressure to read. I am a veterinarian in Bend Oregon in practice for 30 years. Here are some pictures of the .

 

[PabloCruise]

That is a great looking Pig!

It looks like someone shaved the lips off the front wheel openings?

I wonder why he swap w/ a 60 series 4-speed? It looks like they did move the shifter back from the one picture I can see. Seems like a lot of mods for a 4 speed.

 

[Dogdoc90]

That is a great looking Pig!

It looks like someone shaved the lips off the front wheel openings?

I wonder why he swap w/ a 60 series 4-speed? It looks like they did move the shifter back from the one picture I can see. Seems like a lot of mods for a 4 speed.

Front wheel fenders we’re pretty rusted out and we’re just trimmed off. The PO bought used replacement front fenders but never got around to doing the work. I’ve got them if I ever feel motivated but I kind of like the way she looks as is. Everything is working great (except oil pressure gauge) at this point and I think I’m just going to enjoy her as is.

 

[PabloCruise]

Front wheel fenders we’re pretty rusted out and we’re just trimmed off. The PO bought used replacement front fenders but never got around to doing the work. I’ve got them if I ever feel motivated but I kind of like the way she looks as is. Everything is working great (except oil pressure gauge) at this point and I think I’m just going to enjoy her as is.

I am pretty sure whatever year 60 would have the different top plate.
It looks like you have the stock bench seat in there?
Do you like the location of the shifter relative to the seat?

 

[RUSH55]

Yet another great looking 55 out of Oregon!

 

[Dogdoc90]

I am pretty sure whatever year 60 would have the different top plate.
It looks like you have the stock bench seat in there?
Do you like the location of the shifter relative to the seat?

It seems fine. Bench seat is a little soft but the position works for shifting. I’m looking for something to give me a little better back support and that keeps me from sliding down all the time.

 

[PabloCruise]

It seems fine. Bench seat is a little soft but the position works for shifting. I’m looking for something to give me a little better back support and that keeps me from sliding down all the time.

If not too much trouble, could you post a few more pictures of the shifter relative to the bench for me?
Do you know if someone had to modify the holes in the floor for shifter?

 

[Dogdoc90]

If not too much trouble, could you post a few more pictures of the shifter relative to the bench for me?
Do you know if someone had to modify the holes in the floor for shifter?

Floor was rusted out and I can see a weld around the shifter plate so I’ll bet it was modified.

 

[RUSH55]

Definitely prefer those 60 series boots!