Significant automatic transmission leaks

[jangell]

I was only planning on driving it into the ground if some of the expensive hard parts had been damaged. I'd rather save it.

I drove 200+ miles in the last week, and checked the final drive again by removing the fill plug (not the drain plug). It was about half a quart overfilled (I'm just guessing here), or about 42% of what it was overfilled last weekend (I weighed the fluid that was drained).

I pulled the transmission pan and the filter as well. The fluid smells fine (not burned), so that's good. There was a bit of sludge in the bottom that reminded me of a somewhat diluted version of the the gear oil in the final drive, which fits if the final drive and transmission are leaking into each other.

The filter looked good to me. Minor debris, but not much. Also little RTV that fell in there from when I sealed up the dipstick tube a few months bug, and a few flecks, but nothing that looked bad, as far as I could tell.

An interesting detail I remembered: The last time the trans was replaced (I think it was at PJ Grady) is when I kept the old final drive to reduce the price a bit. I remember Rob noting that the final drive seemed overfilled and didn't seem to have gear oil. Given what seems to be happening now, I'm betting that the ATF was leaking into the final drive then, too. This was 7+ years ago (my DMC wasn't running for about 6 years of that time). Now I realize just how hard it is to overfill the final drive, what with the fill point being on the side of the transmission and all.

Anyway, here are some pictures.

The sludge at the bottom of the pan:
IMG_3643.jpg

The sludge poured out into my drain pan, which looks a bit more like gear oil than ATM:
IMG_5020.jpg

The filter:
IMG_1410.jpgIMG_2445.jpg

The overfill from the final drive last week (left) and this week (right):
IMG_2680.jpg

-- Joe

[Michael]

That's either very very dirty ATF or gear oil leaked into the trans. A lot more soft material than you should see too, quite a bit more.

I don't see any metal though so that's good. A rebuild kit from Cobra transmission should do the trick since you more than likely just wore the clutches out. DeLoreanGo may carry them as well.

I just about bet if you cracked that filter open you will see it clogged up on the backside of the outlet ports.

[jangell]

I probably have done some damage to the clutches, since the trans has slipped on me due to the incessant leaking. I do immediately put fluid in when that happens, but by then it's been running low for longer than it should have been.

The last time I changed the trans fluid completely was in January or so, when I filled the car to drive it for the first time in years. It's been between 2k and 4k miles since then (I don't have a working speedometer, so I don't know exactly). Given what is likely the ATF in the final drive, I'm going with it being gear oil as well, rather than very dirty ATF.

The trans actually runs just fine. Shifts are good, and power is fine. It's more the leaking of ATF and gear fluid due to the bad seal that's the main problem. I'm curious how much damage I've done to the clutches and how long I can get away with it as-is. Probably not the 5-10 years I was hoping for before an electric conversion is more feasible. Either way I'm going to have to pull the trans and fix the seal to the final drive, but if I go looking at the clutch packs I expect that I'll be getting into "special tool" territory. Still, probably worth trying to do that and seeing if I can make it work vs putting out the $6k that I don't really have at the moment for a completely new transmission.

I see DeLoreanGo has some automatic transmission filters available (while supplies last, as well as kits for the seals and "steel modules", although I'm not sure what they are). I should probably grab one for when I do the final drive, and then I can cut the old one apart and see how bad it is. I think I have a few thousand miles on that transmission, although I don't recall just how many (something in the 4k-7k range, I'm guessing).

Thanks!

-- Joe

[David T]

You could be slipping because of all of the gear oil in the transmission. You really have to cut the filter apart to see what is there. I didn't see any metal either but you should carefully inspect the magnet. At this point the transmission is probably rebuildable but it needs to be done. Mixing the final drive and transmission fluids is not a good thing.

[Ron]

I probably have done some damage to the clutches, since the trans has slipped on me due to the incessant leaking. I do immediately put fluid in when that happens, but by then it's been running low for longer than it should have been.

The last time I changed the trans fluid completely was in January or so, when I filled the car to drive it for the first time in years. It's been between 2k and 4k miles since then (I don't have a working speedometer, so I don't know exactly). Given what is likely the ATF in the final drive, I'm going with it being gear oil as well, rather than very dirty ATF.

The trans actually runs just fine. Shifts are good, and power is fine. It's more the leaking of ATF and gear fluid due to the bad seal that's the main problem. I'm curious how much damage I've done to the clutches and how long I can get away with it as-is. Probably not the 5-10 years I was hoping for before an electric conversion is more feasible. Either way I'm going to have to pull the trans and fix the seal to the final drive, but if I go looking at the clutch packs I expect that I'll be getting into "special tool" territory. Still, probably worth trying to do that and seeing if I can make it work vs putting out the $6k that I don't really have at the moment for a completely new transmission.

I see DeLoreanGo has some automatic transmission filters available (while supplies last, as well as kits for the seals and "steel modules", although I'm not sure what they are). I should probably grab one for when I do the final drive, and then I can cut the old one apart and see how bad it is. I think I have a few thousand miles on that transmission, although I don't recall just how many (something in the 4k-7k range, I'm guessing).

Thanks!

-- Joe

$.02

If/when you get ready to do pull it out, you might try the following:
Place the D on jackstands.
Add a primary colored die to the gear oil and top it off..
Drain and measure the ATF fluid. Refill with same amount of fresh fluid (engine off).
Separate the cooler lines at the most convenient place to drain one end into a container while adding fresh fluid into the other end, depending on your tools etc.
Carefully: Have helper start the engine and place it in gear.
Keep adding fluid to the cooler line until the converter is flushed and the fluid from the other end is ~normal color.
Watch for die.
Always apply brakes slowly to stop the tires before placing in Park! Shut engine off.
Reconnect cooler lines.
Add a different primary colored die to ATF and adjust level -- It will be cold so leave room for another ~quart.
Restart engine and gently run it through the gears.
(I'd give it several minutes to move the die from one section to another.)
Stop the tires, Park, shut it off.
Inspecting the color of what drains out of BOTH sections will now tell the story...
Hopefully there is no gear oil die in the ATF section and the friction disks are not contaminated...

With the given history, I'm with Michael. If you have installed automatic clutches before, don't worry about D specific (4141) special tools. The clearance for the disks/packs are the SOS (and you can measure most of the heights off of a straight edge across the case as you tear it down, if you really want to...). The rest shouldn't be a problem since there are no significant metal traces or mileage. Hopefully the worst you need is to figure out the fluid mixing and a "frictions only" kit.

[jangell]

Just to be absolutely clear: I am only slipping when I'm low on fluid. I wind up not checking it for too long, it slips a little (or doesn't move or moves too slowly on it's own when putting it in D or R from P), I check and the dipstick is basically dry. Add about a quart, and everything is fine again. All slipping appears to be solely related to running low on fluid. Slipping only happens when the car is cold, and only in first when accelerating from a stop. That doesn't mean that I haven't prematurely worn the clutches, though.

In the interest of providing more accurate information about the life of this transmission, I looked through my receipts and found that I had it replaced 9.5 years ago (early 2010). The car has been off the road for roughly 6 years of that time, so the transmission only has 3-4 years worth of driving on it. Based on my gas receipts from this year, I estimate I've driven 2500 (+/-200) miles over 6 months (~14 tanks of gas, about 180 miles per tank), so we'll call it 15k-20k miles over that 3-4 year period? Which is honestly a lot more than I thought I'd driven, but it's probably correct. I do drive it basically every chance I get, even if I'm just going a mile down the road to the store.

I have never replaced clutch packs in a transmission before, or done anything more than mate it to the engine. The most I've ever done is the engine work for the 3.0L engine swap, which was the first time I'd done something like that either, although I did tear the engine down pretty completely (well, the top and bottom; I didn't go into the pistons/liners themselves), and completely tore down the broken 2.8L engine as a learning exercise.

My classic car mechanic friend has been helping me out with these more complex issues, like replacing the A/C system, some final work with the engine swap, and tracking down other transmission leaks. I eventually get there, but he does it in like a quarter of the time and with more precision than I do. He has done transmission work before, but he's concerned about how delicate automatics are and doesn't want to risk breaking something when replacing the clutch packs, so he'd prefer if we didn't have to do that. He's perfectly fine with resealing everything, though. I should have access to a Renault 4141 shop manual soon, so we'll take a look at that and see how complex it actually is. I'm glad to hear I won't necessarily need special tools, though. Even so, it's unlikely I'll be able to get to this until early next year.

I like the idea of putting different dies in the gear oil and ATF -- I definitely want to make sure that we've really fixed the leak.

Thanks again for all the help!

-- Joe

[David T]

Really no need for the dye test, you can see gear oil in the transmission pan. I agree you *could* get away with just a soft kit of seals, frictions and steels. Figure rebuilding or getting a rebuilt converter. While you can make up the necessary special tools, having the kit makes it much easier. You really do need them to disassemble and reassemble the clutch packs. Really must figure out what went wrong allowing the fluids to mix. To me, that is the source of the trouble.

[jangell]

I was thinking the dye test for after it's all back together again, just to make sure we actually fixed it.

I definitely agree that whatever is leaking is what needs to be fixed. I assumed it was the seals, and nothing to do with the clutches, but I haven't gone through any of the automatic documentation nor do I really know what an automatic looks like inside, so I have no idea how it's arranged.

Thanks!

-- Joe

[David T]

There is a plastic tube that the input shaft runs inside of through the final drive. My guess is something happened to it. There is a picture on G:09:02. If you are considering doing this yourself you might want to make yourself familiar with Section G in the Workshop Manual.

[jangell]

Oh yes, Section G is on my reading list.

That shaft does sound like a good candidate for the leak. I'm guessing it's part 103581, which is of course out of stock at store.DeLorean.com . Hopefully it's just the O-rings, but I'll know once its apart sometime this winter.

Thanks!

-- Joe