LJ78 Prado Rear Diff Leak

[Lee777]

Hi All,

The purpose of this post is to share my experience with disassembling the rear differential and to seek help with problems I encounter along the way.

I was wondering if I could have some advice. I own a 1991 LJ78 Prado, 150,000 kms, and have 2 main problems:

1) I noticed the rear diff is leaking oil where the propeller shaft meets the differential carrier (pinion oil seal?) and also around where the differential carrier meets the axle housing (differential carrier gasket?). THe leaking is significant requiring I top up the gear oil once every couple days and leaves an oil puddle on the ground when the truck sits. Im thinking I need to replace the pinion seal.

2) The rear diff oil plug screw magnet had metal shavings, about half an inch of gunk with a couple of half inch square shavings. Note this was the first time I ever removed the oil plug and cleaned it so Im a bit on the fence about whether I have a thrown bearing problem. I also noticed the truck developed a whine sound around 90km/hr which seems to be coming from the rear drive train. Its not loud or squealing, I just noticed it because it wasnt there before. I know the fluids have been good. I decided since I am going to change out the rear diffirential carrier gasket I may as well inspect the bearings.

I have decided to embark on replacing the pinion seal and the differential carrier gasket.

_______

Pinoin seal replacent:

1) I removed the rear propeller shaft
2) Removed the staked part of the the nut then realized I needed a 30mm socket to remove that nut to get the companion flange off. I dont own one so Ill have to wait till tomorrow to get one in order to keep going.

Onto Differential carrier gasket removal:

1) In the FSM for Removal of Rear differential it says.
a) Remove drain plug and differential oil
b) Remove rear axle shafts: Semi-floating type see page SA-108, Full floating type see SA-116. Im not sure whether mine is full floating or semi floating. Looking at the instructions for the semi-floating type. It looks like with this model you have to access the differential first to remove clips which hold the axles in place at the differential before you can remove the axle shafts. The pictures shows differential cover that can be unbolted. My Prado doesnt have a bolted on cover, its welded on tight (see pic)

The instructions for the full floating say just to remove the tire, drum, and pull the axles out with no need to access the differential which seems easy enough.

Main questions:

1) Is my truck full-floating or semi-floating?
2)While waiting to get the 30mm socket, I removed all the screws to the differential carrier housing and tried to pull it off so I can look at the gasket. I hammered the differential carrier (housing) with a drift and it still wont come off. Do I have to remove the axles before I can get the differential carrier (housing) off?

Thanks !

Lee

 

[kbushnz]

To remove the diff housing you will need to remove the wheel / axles.
It is a semi floating type system.
Wheels off. Brake lines off. handbrake cable off. Undo the four bolts and slide the whole assy out. ZRepeat for the otherside.
I would strongly suggest you head off to the manuals section and download the service manual for the LJ7* series that is in there before you proceed any further.

 

[Lee777]

Thanks Kbushnz

Well, I wonder if this stuff was meant to come apart. I removed 3 of the 4 nuts that hold the wheel assembly. The 4th nut spins with the bolt!!!! The other side of the bolt has a flat side and is inaccessible unless you remove the emergency brake pads!!!

Why on earth would Toyota use these bolts for to hold on the wheel !!! I tried to hold onto the bolt with vice grips, got the nut to move a bit more, but now the whole bolt spins easily. Tried to fix the bolt by jamming a screwdriver between the assy and the nut but the bolt still spins with the nut.

Anyone have any suggestions?

Tired with nuts and bolts

Lee

 

[kbushnz]

Unfortunately its just one of those jobs... Need to pull the e brake shoes out to get to bolts. You either do it right or not at all. No short cuts on this one.

 

[Lee777]

I hear ya. I ended up hammering a flat head screwdriver between the domed head of the bolt and the metal it lays flush too. I was lucky, it was enough to keep it from spinning and I got it off!

To recap, I took off the wheel, unbolted the disc caliper, disconnected the brake line, disconnected the hand brake cable (by removing the cotter pin and bathing the hook in WD-40 eventually working it loose and getting it apart), removed the 4 bolts holding the wheel hub assembly to the axle housing. I pulled the assembly out and stuck it in a garbage bag. This photo is with the wheel assembly removed.

I repeated this process for the other side.
I was then able to remove the differential carrier as seen in the next couple photos:

I noticed when working on removing the wheel assembly there was play when I turned the axle. The propeller shaft was disconnected at this point. Im not sure how important this is. The main reason I wanted the diff out was to replace the gasket but I did see some metal shavings to I'll take the diff carrier to a transmission shop along with the FSM and have them disassemble it and identify if any bearings need replacement.

I may as well have them replace the pinion seal and bearings while their at it.

Lee

 

[Rummat81]

You might want to the outer wheel bearings and seals at the same time.

 

[Lee777]

HI All,

I found some time to disassemble the rear diff so I can replace the pinion oil seal on my '91 Prado LJ-78 EX5. I found some steel hardware at the local village lot and fashioned a brace to hold the flange while I unscrew the pinion nut.

Once I go the nut off, I pulled the companion flange. The next pic shows the disassembled parts.

You can see in the picture above, there is a seal seated around the pinion. I was wondering if I can get some help at this point. I felt inclined to take a screwdriver and destructively remove that oil seal but when I looked at the new oil seal I ordered, I noticed the new oil seal looks different. The new oil seal has a rubber inner portion that extends along the rotational axis of the pinion both sides whereas the old one I see here installed (in this picture), is flat on the side that we can see. I was wondering if anyone has any advice on what I do next.

BTW here are the parts I ordered for the job (from Radd Cruisers).

Pinion Seal:

Crush Sleeve:

Thanks for your help!

Lee

 

[Lee777]

Here is a diagram from the FSM

I took a screwdriver and destructively removed that oil seal. The next picture shows the new seal compared the old one.

It looks like the new seal has an improved design. The seal extends outwards providing more contact with the pininon surface.

If I remove the oil slinger I can see the front bearing:

IT says on the oil seal packaging, when replacing the oil seal you have to also replace the crush sleeve (what is the reason for this? Does it reset the preload?) Looking at the FSM diagram, is the crush sleeve the same thing as the "bearing spacer" located behind the front bearing and the race? If I have to replace the crush sleeve does anyone have any ideas on how to get the front bearing out? Its stuck tightly to the pinion shaft.

Pic of crush sleeve:

Thanks for help
Lee

 

[kbushnz]

The replacement seal has the extended end to help keep dust and debris out. Factory seals normally have this. I have seen aftermarket ones with no lip.
As for the crush tube, I have never replaced the tube. I mark the location of the original nut and install it back in the same spot. Or just a tad tighter to get a new bit of metal to stake the nut.
Never had any issues.... But that's for my front diff. The rear has a solid spacer put in it when I had it last apart. So its just torque it up and restake the new nut (if I use one).. I am sure others will pipe up and offer their opinions also.

 

[Sd1975]

Do these use the 4 cylinder or 6 cylinder carrier bearings

 

[kbushnz]

6 cylinder...

 

[Sd1975]

Thought so thank you, so 50mm?

 

[GTSSportCoupe]

Thought so thank you, so 50mm?

Not sure if you know, but you can go here to find all the drawings and part numbers for your vehicle (and many others): 1991 - 1993 Toyota LAND CRUISER LJ78 OEM Parts | Japan sales region, , 910807

And then you can go here and do a cross search to other vehicles. ToyoDIY.com This can help when you want to cross one of the JDM parts to a north american model like a 4runner or something.

I use those two sites all the time when I'm looking for parts. Megazip will also give you newer part numbers for parts that have been succeeded.

For the JDM only parts, Megazip is a legit site and can be ordered from. You can also use Amayama, Partsouq, etc. Or your local cruiser parts supplier if they have the part.

 

[Sd1975]

Great info thank you! I'm learning lol