Delica Canada | Mitsubishi Van Club

So yesterday i was under the truck changing all the drive line fluids and greasing all the ball joints and u joints and i came across this. i think that my "pinion seal" is shot?? i don't have too much experience with "pumpkin style" diff's but it seam that this seal is shot and now it is spinning gear lube all over the under body of the truck. and on to my exhaust pipe.... SWEET!

am i wrong in thinking that all i have to do is disconnect the prop shaft at the diff and slightly tighten the "pinion nut" and replace the pinion seal to solve this??

also when i replace the lube in the limited slip, should i buy the mitsubishi product or does someone know of a good alternative from lordco??

I'm not sure if those LSD types use a crush collar or hard spacer for the pinion shaft. However, tightening the pinion nut will not solve your issue and if it does use a crush collar you'll do some damage to the pinion/ring gear and pinion bearings. The pinion seal will have to be replaced.
Also check the venting into the rear axle/banjo and make sure it isn't clogged up with mud. If air can freely move in and out of the axle it will expand when hot and blow out the pinion or axle seals.

john n wrote:I'm not sure if those LSD types use a crush collar or hard spacer for the pinion shaft. However, tightening the pinion nut will not solve your issue and if it does use a crush collar you'll do some damage to the pinion/ring gear and pinion bearings. The pinion seal will have to be replaced.
Also check the venting into the rear axle/banjo and make sure it isn't clogged up with mud. If air can freely move in and out of the axle it will expand when hot and blow out the pinion or axle seals.

ok i will inspect the breather first... could you briefly explain how to replace this seal. thanks lot

I've been searching to see if I can find a diff manual, but haven't had any luck.
You should beware that if this isn't done properly you will severely damage or destroy your diff.
The basic steps to change the pinion seal are:
- lift and secure the vehicle off the ground in neutral, no park brake, drain diff.
- mark the driveshaft and pinion flange prior to disassembly, so you when you put it together it won't have balancing issues.
- once the driveshaft is off make a tool out of some heavy flat bar 1/4" x 2" x 16" would be a good size, that can bolt up to the pinion flange, but also allow access to the pinion nut. You'll use the same bolts that attached the driveshaft to the pinion flange. Just use two holes on one side of the flange so you can get at the pinion nut.
- prior to mounting that tool push the pinion flange up and down - if there is any play, you have bigger issues than just a seal.
- turn the flange by hand and feel how much resistance there is, get a good feel for it, you'll have to replicate it later.
- Mount the tool onto the flange, note that there is probably a staked nut holding the nut stationary. Put a 1/2" bar with a socket onto the nut, trap the tool and take off the nut.
- gently tap on the back side of the flange to remove it.
- inspect the seal prior to removing it for splits etc, use a heavy screwdriver to pry out the seal. Note and measure how deep the seal is recessed into the housing (if at all).
- clean everything up, use some emory cloth on the face the seal rides on.
- wipe some good quality silicone sealer around the outside edge of the seal and grease the inside edge
- install the new seal by gently tapping it in with a light ball peen hammer. You can easily ruin the seal by whacking it hard, it's a gentle process just little taps around the outside until it settles squarely into the housing, set it to the required depth.
- install the pinion flange and start to tighten up the nut.
- remember the staked nut? tighten the nut until the staked part of the nut lines up with the slot in the pinion.
- remove the tool you made and turn the flange, is it the same feel as before?
- make sure there is no fore and aft play in the pinion, the object is to get the same torque as what was set in the factory.
- if it all feels good, stake the nut again to ensure it doesn't back off, if the staking part of the nut broke off in taking it apart, use a pin punch to stake the nut to the pinion shaft on the opposite side - crude but effective.
- driveshaft on marks and torqued
- fill diff
- lower and test drive.

Anybody out there see anything I have missed or other ways of doing it?

Raule Duke wrote:also when i replace the lube in the limited slip, should i buy the mitsubishi product or does someone know of a good alternative from lordco??

Only put one of two things in there otherwise you may damage the diff :

1. Limited slip differential fluid

or

2. 80w90 gear oil w/ LSD additive




If you've never replaced a pinion seal, pulled/adjusted spyder/slip gears then don't do it yourself.



It's a straightforward job if you are a mechanic and have the proper tools (seal driver/torque wrench)

If you are not a mechanic and don't have the right tools, like John said, you can literally have your diff blow up if you do it wrong.




If you have never done it, have anyone who has done it to watch/help. If you do it yourself and disregard advice, then John's laid out the steps well.




For the Pajero specifically (same as the Montero diff's) here's the goods :

Removal :

Raise the Paj and support it safely on jackstands.

Matchmark and remove the driveshaft.

Check the turning torque of the pinion before proceeding. It should be 3.5-4.5 inch lbs. (0.4-0.5 Nm). This is the torque that must be reached during installation of the pinion nut.

Using a suitable pinion flange holding tool, remove the pinion nut and washer.

Remove the companion flange from the drive pinion.

Pry the pinion seal out of the differential carrier.

Install :

Clean and inspect the sealing surface of the housing.

Using a seal driver, drive the new seal into the housing until the flange on the seal is flush with the carrier.

With the seal installed, the pinion bearing preload must be set.

Tighten the pinion nut (a new self-locking pinion nut must be used) while holding the flange, until the turning torque is the same as before removal. The final pinion nut torque must be between 137-181 ft. lbs. (190-250 Nm).

Align the matchmarks and install the driveshaft.

Check the level of the differential lubricant when finished.

Here's the diagram you're asking for :

Perfect.
Thanks for the added info that I was missing.

WOW

thank you both very much!!! it all seems straight forward enough, the only thing is i don't have a torque wrench that reads inch pound so i'll ask my buddy to borrow his. also when i ordered the seal from Mitsubishi i didn't order the Nut so i will order that before i do this project.

i can't thank you both enough for the great info!!!!

hey jfarsang where did you get that diagram from?

cheers
cj