87 2WD AUTOMATIC REAR TRANSMISSION OIL SEAL LEAK

[daverave64]

Hi
I purchased this van a few months ago and getting it ready for summer, I have chased down and repaired most of the fluid leaks. Yesterday I pulled the driveline and replaced the rear seal at the transmission, it was dripping and making an ATF mess. I noticed when the driveline was removed that the splined shaft coming out of the transmission has some play about 3mm or 1/8" maybe a little more, should that shaft have any movement?
I changed the seal out with an OEM replacement and took it for a test drive, still leaking. Maybe I buggered the seal driving it in but it went in pretty clean.
Thanks for your time
David

[JPERL]

There is a bushing in the extension housing that needs to be replaced as I recall. I had this issue on my 87 back in 1996 where I had a leak from the rear extension housing and replacing the seal first did nothing to stop the leak and then changing the seal again and the bushing resolved the leak and the play in the driveshaft. I don't know if this is an available part perhaps when you tap the old one out it can be matched or cross-referenced to another compatible application. Best of Luck to you

[nikifix]

The tail housing bushing is readily available from Rock Auto for a few dollars

[daverave64]

Thank you for the information, new bushing and seal cured the major leak. Will take more pics in the future and post them.

[micah202]

Any details for replacing the tail housing bushing?
Can it be done externally, without removing the housing?
The factory manual is surprisingly sparse in this regard. It only mentions how to service the speedometer pickup.

[MarkH]

Any details for replacing the tail housing bushing?
Can it be done externally, without removing the housing?
The factory manual is surprisingly sparse in this regard. It only mentions how to service the speedometer pickup.

I just replaced the seal and bushing on mine over the last couple of days (my van is a 1st gen 1985 automatic). I'll attach a bunch of photos and a description below, but the short answer is "no", there's no way I could have done it without removing the tail housing.

My transmission tailhousing seal has been leaking since I got the van a few years ago. There is a mess of new and old automatic transmission fluid all over the underside of the van and the gas tank in that area. At first it didn't seem that bad so I left it, but then I noticed that I was having to add quite a bit of fluid recently so I decided to change the seal. I ordered 2 seals (in case I damaged one putting it in), the metal bushing and a tailhousing gasket off Rockauto for a few dollars each.
I drove the back of the van up on wheel ramps to get more clearance for me to work under it.
A view of the output shaft before I started removing anything:
I removed the 4 bolts from the flange where the shaft goes into the differential. I had to tap it a few times with a hammer to break the flange free:
I then pulled the splined end of the shaft out of the transmission extension housing:
There was a bit of pitting on the end of the shaft where it sits in the seal. I was hoping that this wouldn't be too much of an issue with sealing with the new seal:
View of the extension housing with the shaft removed. I've seen Youtube videos of people leaving the extension housing on and prying out the seal and using a special tool to slide into the bushing and a slide hammer to pound it out. To me, this seemed like it would be a lot of hammering force on the aluminum transmission housing, which might risk damage. I wasn't in a hurry so I decided to remove the extension housing so I could remove and replace things in more comfort on a shop table.
I supported the transmission with a car jack and a piece of wood to protect the drain pan:
I removed the speedometer cable:
I removed the large transmission mount bolt above the extension housing. A lot of the oilyness in the photos is from penetrating oil that I sprayed all over the bolts:
I then removed the 6 bolts holding on the extension housing. The manual says to remove the gas tank support mount nearest to the extension housing since it is kind of in the way. I didn't bother and it took a bit of wiggling to slide the extension housing out past the gas tank mount. I also didn't bother draining the transmission fluid before I started since I figured that the steep forward angle of the van up on the ramps would keep the fluid at the front of the transmission. It turns out that when I loosened off the extension housing, about a liter and a half of fluid still drained out. I was quick enough to catch it in a drain pan.
I covered the exposed components with a plastic bag to protect them:
The removed extension housing. So far, this removal only took me less than an hour, which is unheard-of for me. Usually, quick 15-minute car repair jobs end up taking me 2 days because of seized bolts, sheared-off bolts, wrong parts, etc.
At my work, I have access to a machine shop with all kinds of presses and tools so I brought the extension housing there to do the seal/bushing replacement. I removed the speedometer gear housing and replaced the o-ring, which was pretty flat. It wasn't leaking or anything, but I figured I might as well since I had everything out:
Now to remove the output shaft seal. In the past when I've removed seals like this, I just pried them out with a flathead screwdriver or screwed a small screw into them and pulled on it with pliers. Today, prying didn't work. I tried tapping the seal out from the back with a hammer and punch, but it still wouldn't budge. I tried using a slide hammer, but the seal was still jammed in there too tight. I ended up having to use a small cutting wheel on a Dremel to cut away part of the the metal outer ring to relieve the tension if that makes any sense. The shredded seal then eventually could be tapped out. I was careful not to damage the aluminum surface of the extension housing that it sits in. I don't think I would have been able to remove this seal while lying on my back under the van. This photo shows the removed seal and another metal-backed felt dust seal that was installed on top of it. This felt seal is shown on some parts diagrams, but I don't know how common it is to use them.

This photos shows the end of the extension housing with the seal removed and the metal bushing visible:
I then tried all kind of tricks to get the bushing out. I tried tapping it out from the back with a hammer and punch. I tried using an arbour press (I didn't want to use a hydraulic press, since the forces involved could easily destroy the extension housing if the bushing wouldn't move). I tried using a slide hammer. Nothing would make the bushing come out. I ended up using a hacksaw blade to cut partially through the bushing and the a hammer and chisel to split it partway along its length. Like with the seal, this relieved its internal forces and allowed me to finally tap it out from behind. There is now way I would have been able to remove this bushing with the extension housing still installed under the van. The old bushing:

I then had to put in the new bushing. It has an oil hole that has to be aligned with an oil passage in the housing. The housing has 2 oil passages so I assumed it didn't matter which one I used and aligned the hole with the right side passage. Maybe there's more to it than that, but at the time I didn't put too much thought into it. I tried using the arbour press to gently press in the bushing, but I could tell it was going to be a very tight fit and it wasn't going in. I sprayed the bushing with a semi-legal spray can of R134 to cool it way down and hopefully shrink it enough to go in easier. I then machined a brass insert to sit in the top of the bushing that I could use to press it in if that makes sense. I then tried using the arbour press again, but the bushing still wouldn't go in. I ended up using a big hammer to pound it in. The steel handle of the hammer broke since I was hitting it so hard so I had to use another hammer. It took about 30 whacks to drive the bushing in. My whole plan of taking out the extension housing so I could replace things more gently had gone out the window. The new bushing installed:


I then installed the new seal. I don't like the idea of using any kind of sealant around automatic transmissions since any extruded bits of dried sealant can theoretically get stuck in components of the valve body, but I put a very thin film of silicone sealant around the outer rim of the seal. I was worried about the metal-on-metal interface of the outer part of the seal allowing small amounts of fluid to leak past if the seal didn't slide in perfectly. The new seal went in fairly easily. I gently tapped it in with a plastic block and a hammer.


I then re-installed the old felt dust seal, which for many vehicles probably doesn't exist.


So removing/replacing the seal and bushing was done and it took me a few hours, which is way longer than I expected. Youtube makes it look so quick and easy. The next day I replaced the extension housing on the van. In hindsight I should have ordered 2 new gaskets since they are very thin and fragile paper and very easy to rip. I lucked out and didn't damage it during installation, but it was only a couple of dollars so having 2 on hand would have been less stressful. I used a thin layer of gasket sealant on the gasket. Again, I'm not a fan of using that stuff with automatic transmissions, but the thin paper gasket would have leaked for sure without it. I put a bit of grease on the splines and seal. Theoretically I should have used auto trans fluid since that is its usual lubricating medium, but I wanted something thicker and more protective for installation.


When the time came to reinstall the output shaft, it wouldn't slide in past the bushing. Before I installed that bushing, I slid it over the end of the shaft and it slid on fine. Now that it was installed in the housing it was too tight for the shaft to slide in. I was too stubborn to remove everything again and try and hone the bushing or whatever to try and make the shaft fit so I whacked the shaft in with a hammer. I had to hit it pretty hard a bunch of times before it was gradually forced in. Every technical bone in my body was screaming at me that I was destroying something. I was worried that the bushing was being forced further back in the housing although the amount of force I had to use to install the bushing told me that it probably wasn't going anywhere. In hindsight I assume that all the hammering I did to install the bushing mushroomed out the end of it just enough to interfere with installing the shaft. I hoped that the tight clearances would wear in as the shaft rotated. I bolted everything back together, tightened up the drain pan bolts while I was under there, lowered the van, topped up the fluid level and test drove it. There were no strange grinding sounds from the tight bushing and it seemed to all work fine. It has been a couple of days now and as of yet, the new seal isn't leaking. I had tried to clean up the pitted surface of the shaft with fine sandpaper, but the surface still wasn't smooth in places so that is still a bit of a worry. I'll have to check for leaks regularly before I'm confident that the repair was a success.

[micah202]

Wow Mark H, thanks for the very detailed outline of your work.
You mentioned the manual at one point. I have a factory shop manual but found nothing! If you have the same factory manual, can you let me know the section it is in, maybe page reference?

... I have the luxury of having a spare transmission in my man cave, so I pulled off the housing from that. It lets me do that core work, then replace the one that's on the van. The idea of using a hacksaw on the old bushing sounds like a plan.

[MarkH]

Wow Mark H, thanks for the very detailed outline of your work.
You mentioned the manual at one point. I have a factory shop manual but found nothing! If you have the same factory manual, can you let me know the section it is in, maybe page reference?

... I have the luxury of having a spare transmission in my man cave, so I pulled off the housing from that. It lets me do that core work, then replace the one that's on the van. The idea of using a hacksaw on the old bushing sounds like a plan.

I have the 1985 factory service manual. The only reference to the tail housing is in the governor servicing section. That's where it mentioned removing the gas tank bracket. As far as the seal replacement goes, there's no mention of it that I could find. And according to the FSM, the bushing may as well not exist since there's no mention of it.

[micah202]

[QUOTE=MarkH;49091/QUOTE]

Yah, that's pretty much what I found in the manual. Strange.

Another interesting factor is this mechanism that is inside the housing on my spare transmission. I don't see it pictured in yours.
...did you have one,, or should I be wary about differences between model years?

[micah202]

oops, here's the picture.



Yah, that's pretty much what I found in the manual. Strange.

Another interesting factor is this mechanism that is inside the housing on my spare transmission. I don't see it pictured in yours.
...did you have one,, or should I be wary about differences between model years?

[MarkH]

Hmm... Now I'm a bit worried. My '85 van has a different transmission than the 2nd gen vans so at first I assumed that tube in your picture was for the 2nd gens or something, but then I looked up a parts diagram for my 1st gen and the tube is still there.

I assume it's to provide some forced lubrication to the splines and bushing of the output shaft. In my photos, I can see that the circular mount thing that the tube sits in is present in mine, but the tube is missing. I wondered if maybe it fell out without me noticing when I removed my housing although it's unlikely since it would be held in that little hole in the circular bracket. I looked around in my driveway anyway where I was working and it wasn't there either. So it seems like that tube is missing from my transmission. Looking at the photos of the exposed end of my transmission after I removed the output housing, I can't really wrap my head around where this tube would "plug" in to if it was supposed to deliver pressurized fluid through it. I'll have to do some more internet searching to try and figure out what that tube is exactly for and if it's necessary (I've been driving my van for about 3 years without it). On yours, does it look like the end of this tube plugs into anything in the trans? It seems like it would be a pain to ensure that it lines up properly without being able to see it when you're re-installing the housing on the trans.

[MarkH]

I found this patent application from Toyota in 1984 that explains what this tube is for (more reliable lubrication for the bushing). Since that's around when my van was built, maybe it wasn't installed yet in my trans and maybe the extension housing was a later replacement on mine and not an original. Patent.pdf
On this photo of my trans, it looks like where the tube should plug in is blocked off.

[micah202]

Ah, sorry to raise a concern for you.
Good sleuthing on finding the diagram.
Here's another pic, oriented as per your photo. Indeed that does look like the point of connection. If it's any consolation, when I take a hose and try and blow through the tube on mine, it seems to be plugged.