Final drive leak; does this bolt go through?

[jangell]

I few months ago I installed a Hall sensor on my rear driver's side axle for eventual use as a speedometer pickup. I've been sidetracked and haven't gotten to that yet, but I do have what I think is a final drive leak in that area now.

To simplify the installation, my friend (who was helping me at the time) reused an existing bolt on the output shaft collar thing. I'm having trouble finding picture of that part in the parts manual, so here's a picture of it installed (the blur on the axle is because this is from a screenshot of a video I took while trying to track it down).

Screen Shot 2019-06-30 at 3.12.15 PM.jpg

We tried thread sealant on the bolt, but that didn't seem to help. I thought it might have been the lip seal and got a replacement set, but once I cleaned everything off it seemed like the like was localized to that bolt, so I haven't replaced the seal yet.

Before I go any further, does this bolt go through the transmission into the fluid reservoir, or is it into a blind hole? Meaning, does it make sense that it would leak there?

Also, I'm wondering if I should move the Hall sensor to a different bolt. In principle this should be fine, but I can't help but wonder if it's presence is causing the leak, odd as that might be.

Thanks!

-- Joe

[jangell]

I pulled the bolt out again, put it back in, and it's not leaking. No idea what's up, but there you go. Also, I realized it's not a through hole into the reservoir, because if it was it would be pouring fluid out when I took out the bolt -- that hole is below the fill hole on the final drive.

My current theory is that somehow the top connection to the trans cooler, which wasn't tight enough, was leaking in a way that got fluid to the other side of the engine, since I also tightened that just before re-fitting that bolt. I don't know how it would have gotten there, but it's all I've got.

I put some cardboard under the car and I'll see if it's wet tomorrow. I'll just chalk it up as a mystery fix if it's dry.

-- Joe

[jangell]

I checked the cardboard this afternoon and it was soaked. The bolt and Hall sensor were dry, though. I’m guessing it’s the lip seal, given the location. I’ll try to replace that in the next few days.

— Joe

[Ron]

There is another possible source in that area. There is an o-ring near the end of the "output shaft" (side gear) that keeps oil from traveling along the flange splines and out the flange's roll pin holes. If it is leaking where it sits now, you might want to plug them and see if it leaks, as a test.
103120
100171 (or 110539 for VIN 2680 on)*
103199
SP10090

*If the flange is bad be aware that the parts manual number for your VIN is 100171 which shows "no results" at the DMC online store. I don't know the difference. To make matters worse, there are others out there that have the roll pin hole in the wrong place. It will go together but the o-ring does not get compressed enough, so it weeps.

If you replace the o-ring I strongly suggest you get it from DMCMW...

[jangell]

Looks like that O-ring is 103691 in the automatic final drive (although I wouldn't be surprised if they're the same thing). I'm not entirely clear on where that O-ring is based the diagram, but I expect it will be more obvious when I'm doing the lip seal, but I'll check the roller pin first to see if it's wet. I bought a complete set of parts from DeLorean Go for the job, so in theory I have everything I need, but if that O-ring isn't in there, I'll contact DMC MW for one.

Thanks!

-- Joe

[Ron]

If you meant that you purchased a flange from DeLorean Go, I'd suggest that you use their o-ring with it.
(NOT to suggest that it may be one of those that are different/wrong.)

[jangell]

I replaced the lip seal and the O-ring on the shaft this weekend. That wasn't too bad. What sucked was getting the roll pin back in. Then it took me a bit how to figure out how to refill the final drive (a long rubber hose and drilling a hole in the bottom of the bottle to let air in as the fluid left the top did the trick, after I spilled a bunch of it). I did not put a sleeve on my flange, as it did not have any pitting or scratches in it (I mean, it had super light surface scratches, but nothing that seems like it would warrant sleeving).

But it still leaks. There doesn't appear to be any oil above or within the diff adjustment nut (as in, where the flange and lip seal are), but it's collecting on the "key" that locks the nut in place. I would take a picture, but the leak never seems to show up on camera. I'm thinking that it's seeping from the bottom edge of the nut onto the key. My Delorean Go kit included the O-ring for the diff adjustment nut, so I plan on trying to replace that this weekend. I understand that it is highly recommended to never touch that nut, so this should be interesting.

I'm curious, though: This is a very minor seep, so would turning the nut a couple of notches fix it? Assuming it doesn't screw up the diff, that is. Dave T's post in another thread suggests I should not do that...

Thanks!

-- Joe

[Josh]

I replaced the lip seal and the O-ring on the shaft this weekend. That wasn't too bad. What sucked was getting the roll pin back in. Then it took me a bit how to figure out how to refill the final drive (a long rubber hose and drilling a hole in the bottom of the bottle to let air in as the fluid left the top did the trick, after I spilled a bunch of it). I did not put a sleeve on my flange, as it did not have any pitting or scratches in it (I mean, it had super light surface scratches, but nothing that seems like it would warrant sleeving).

But it still leaks. There doesn't appear to be any oil above or within the diff adjustment nut (as in, where the flange and lip seal are), but it's collecting on the "key" that locks the nut in place. I would take a picture, but the leak never seems to show up on camera. I'm thinking that it's seeping from the bottom edge of the nut onto the key. My Delorean Go kit included the O-ring for the diff adjustment nut, so I plan on trying to replace that this weekend. I understand that it is highly recommended to never touch that nut, so this should be interesting.

I'm curious, though: This is a very minor seep, so would turning the nut a couple of notches fix it? Assuming it doesn't screw up the diff, that is. Dave T's post in another thread suggests I should not do that...

Thanks!

-- Joe

Do not touch that nut. It is for the preload on the differential. It will not solve any of your issues, rather create more.

[jangell]

Would that be with regards to changing its position, replacing the O-ring behind it, or both? I'm guessing that since you said "do not touch" you mean both.

I'm at a loss about how to fix the leak, if that's where the leak is. Or at least that appears to be where the leak is coming from...

-- Joe

[Ron]

The o-ring goes on the adjusting nut, not behind it. (Being the reason tightening it to help the leak would be useless at best.)

Since it leaks just sitting, it seems to me that if the adjusting nut o-ring or the lip seal leaked, there would be oil collecting at the bottom of the nut too/instead. But it is at ~7-8 o'clock, by the adjusting nut key-retaining bold. So at this point, I would remove the retaining bolt and set all it holds aside then spray the area with ether and see where it goes and hopefully comes from. ...Without spinning it. (Which is always the highest point when something leaks while sitting of course).
Baby powders may help you find it and/or show up in pics, fwiw.

From the pic alone, it looks like it may have a source above and to the left of the adjusting nut (out of view?) and follows the nut around until it gets to the "key" and collects. IE, I don't know what it might be, but it makes more sense than the lip or o-ring seals leaking and the bottom of the nut clean.

Fwiw, if the trouble you had with the roll-pin was that you had to hold the flange in a bit to align the holes, that is a good thing. It shows the side gear o-ring was being compressed.