Significant automatic transmission leaks

[jangell]

I put a quart of fluid in my automatic a month ago. Yesterday I put in another full quart when I noticed it slip slightly when cold. That can't be good.

After about 10 minutes of driving last night, I put some cardboard under the car. I checked it about 16 hours later, and I found this:
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I've marked up where I think the fluid dripped from here:
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- The centerline drops are just the low point where the leak collected before dripping down
- The pan isn't actually leaking (of any note, anyway) -- I cleaned that up quite well and properly torqued the bolts and everything. It's in very good shape. I think it's just that some fluid collected there and leaked off of it.
- The cooler is still leaking a little. I've just been dealing with it, because it's not leaking a lot.
- The majority of the leak seems to be coming from the driver's side of the final drive near the axle. The entire bottom of the torque converter housing (whatever that part of the trans is called) is wet. I think it's in a line because that cardboard was a bit warped, so it drained to the lowest point.

I want to be clear that I don't know if this is final drive fluid or transmission fluid. I'm thinking final drive fluid, but I'm not totally sure; I'm not good at identifying car fluids.

More pictures from under the car:
- Wet casing below the torque converter casing thing. You can also see the drips on the centerline near the drain plug for the final drive.
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- The leak has even gotten onto the subframe under the engine.
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- The pan looks fine. I think the liquid on it is just condensation (water). Not quite sure what those black oil-like flecks on the blue joint for the coolant hose are, though. It seems the e-brake line is rubbing against the edge of the pan, so it might be that it's wearing away/melting the rubber and causing it to "splash", but that doesn't seem right...
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- The ever-present trans cooler leak. I'll get that nut tight enough someday... or replace it with an alternate cooler.
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- Drips from the final drive. That black thing with the wires is the hall sensor for my speedometer. The green-brown fluid is final drive fluid.
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The thing is, this doesn't like like trans fluid to me, but rather gear oil. I replaced the driver's side drive flange a couple months ago, which did seem to reduce the leaking at that point, but this is notably worse. Today I raised the car up on all corners, making sure it was level, and removed the final drive fill plug, and immediately fluid poured out. I had filled this when I replaced the flange, and it was only full to the bottom of the fill hole.

My friend theorized that a seal between the transmission and the final drive has failed, and that transmission fluid is getting into the final drive, which in turn is forcing out the gear oil.

I'm tempted to remove the final drive fill plug and catch all the fluid that comes out, just to see how much extra is in there.

Has anyone seen this kind of thing before, and any idea what it might be? Is it some seal between the trans and final drive? I notice a lot of automatic transmission parts aren't available, and I don't want to buy another one (I'm on my fifth; I'm getting tired of this, and this one only has like 5k miles on it), so hopefully this is a fix that doesn't require special tools with available parts.

I was hoping I wouldn't have any real drivetrain problems for another 5 years or so, when electric conversions were more affordable and I could ditch this garbage transmission once and for all, but we're not quite there yet.

Thanks!

-- Joe

[Michael]

From your "droppings" that doesn't seem like a big enough leak to account for the loss you have experienced.

I would start by cleaning everything off very well with brake cleaner and going for a short drive then inspect the usual suspects first (dip stick seal, plug socket, cooler hoses). You may want to have a peek as soon as you stop while the engine is still running, then again in about 10 minutes after you shut it off.

If the main seal between the final drive is leaking, you should smell gear oil when draining the trans fluid. I don't think the trans fluid would go up to the final drive but gear oil would leak into the tranny. (I'm just guessing there but you can pull the top plug on the final drive and see if it's overfilled). You probably have an axle seal leaking as well as the trans leak but that in itself doesn't mean the main seal is leaking.


BEdit. Baaahhhh...I just read ALL of your post and it seems like you are one step ahead of me. Maybe trans fluid can leak onto the final drive.

[jangell]

:) I’m the kind of guy who writes really long posts, then starts replying almost as soon as I started reading another post, so no worries.

My mechanic friend suggested I pull the fill plug and see what I get. It emptied about 1/8 of a gallon jug. And the fluid was definitely more red than the greener gear fluid input in.

I drained the final drive completely and refilled I with new gear oil, 80w90. My friend suggested driving it for a few days, then checking how overfull the final drive is again. That should tell us how bad the failure is.

He also said he’s had this same failure in his Alfa Romeo Milano, and he’s confident we can fix it if the parts are available.

A shot of all the fluid that came out when I removed the fill plug:
https://uploads.tapatalk-cdn.com/20191005/bea49dc131825e36f4dcbe03ce3111d9.jpg

— Joe

[Ron]

The trans fluid would mix quickly and thin the gear oil way down...Comparing the old gear oil to the new, was it a lot thinner?

I agree, one quart low shouldn't make it slip, normally. Could of been air since you don't know where the leaks are...

EDIT: How many miles for the 1 Qt?

[jangell]

Yes, much thinner. It easily poured out of the drive, and what I got on my hands felt thin, much more like ATF. Actually having new gear oil to compare it to made it obvious. The new oil took forever to get out of the bottle even after I drilled a hole in the bottle to relieve the vacuum. It took 5-10 minutes per bottle filling the drive. It took far less time to drain it.

— Joe

[Jonathan]

Best way I’ve found to determine what fluid it is that is leaking is to put a white plastic tray under the car instead of cardboard. I use a big one that started life as a meat and cheese tray for some SuperBowl party I had. Very easy to see if the fluid is bright pink or not that way.

The dipstick tube seal is another PITA that can leak a lot on the driver’s side.

[jangell]

I’ll keep that white plastic trick in mind.

The dipstick tube seal was a project earlier this year. Turns out that the replacement tube I got needed to be bent more to clear the body, or else it sat at an angle. After bending it a bit further it fit much better. I also used an otterstat gasket in placebos the o-ring. It works quite well now, with no leaks. At least there, anyway. :)

— Joe

[David T]

While it is possible for the transmission fluid to leak into the final drive, it is not a common failure especially if the transmission was never disassembled. If it was, then it is more likely. Make sure you are not overfilling the transmission. Follow the procedure in the manual. As for slipping when cold, replace or clean the filter. Any slippage is bad and you can destroy the clutch packs very quickly. Take a picture of the amount of debris in the pan when you drop it to change the filter. If you see a lot or you see ferrous metal, the transmission is done for. A little brass/bronze is OK along with friction materiel. Test the line pressure and do all of the external on car checks and adjustments.

[jangell]

Thanks David. I'll try to get the pan and filter off this weekend and see what it looks like. I'll check the manual for how to test the pressures. If I find the trans is wrecked, I'll just keep driving it until it stops working, I guess, since AFAIK it's impractical to repair them.

Since the car was off the road for 6 years, and the last trans I had was before that, I don't exactly remember the details, but I think this is the one where they were able to reuse the final drive and attach it to a new trans to bring the price down a bit. This means that it has come apart before, and may explain the leak.

One of the transmissions I had replaced was due to a weld failing (I had 1st but lost 2nd and 3rd), so I may just be a target for unusual failures.

As for slipping, every time it's happened it's been because the fluid is low. And the instant I notice it I check the level and put more fluid in -- I keep ATF in the trunk. I do the same if I feel like the car isn't rolling when I put it into gear from park, too. I've been trying to check it regularly, but I have a horribly time reading the dipstick It always seems either completely wet, with varying thicknesses of "wet", or (more rarely) completely dry, which happens when I notice a slip, but it seems I can never find the line when I try to read it. I can read the engine oil dipstick just fine; it's just the ATF dipstick I can never seem to manage.

I have destroyed transmissions before by not noticing the fluid levels, so I'm trying hard to keep it properly filled, but it's not making it easy.

-- Joe

[David T]

Best not to destroy the transmission, they can be rebuilt but not if you damage a lot of expensive"hard parts" like gears. Switching just the transmission is doable BUT. You must shim one of the clutches based on measurements from the final drive. Failure to do the swap properly will condemn the swap prematurely. And of course you must make sure you don't leak into the final drive. That is why it is best to replace the whole transaxle assembly in one piece.

[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:
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The sludge poured out into my drain pan, which looks a bit more like gear oil than ATM:
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The filter:
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The overfill from the final drive last week (left) and this week (right):
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-- 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

[Ron]

Ah, I misunderstood:
I thought you were saying that your friend was confident...but you were worried about the cost of the special tools (mentioned in the manual). And on the die first, it seemed you were not sure if they were sharing. If you are, whether you are going to skip the clutches or not, don't forget the gear oil needs to be flushed out of your lines, cooler(s), and converter. Ya don't really need to add die after you have it back together (If you can tell now w/o it, after all of the cleaning, new fluids and level checking, you won't have any problem telling later ;-).

[jangell]

No problem. My friend is confident he can reseal the transmission. He's not confident about replacing the clutch packs. Before he switched to classic cars he worked at a Mercedes dealership and had to change clutch packs a few times. He found that you could be doing everything right, and still knick the pack and damage something, so he's wary of doing that on any car now. I have no idea how that trans compares to the DeLorean's, nor how likely something like that is to happen when working on the DeLorean transmission.

I sort of wish the trans was fried (or more fried), since then I'd be less worried about breaking something when taking it apart. With the engine swap, I was being really careful not to mess anything up in the 2.8L right up until I a hole in the block. After that, the engine became a learning tool to see how everything went together, and if broke something it wasn't a big deal. That, and a 3.0L engine is only a few hundred dollars, so if I screwed that up I could get another one pretty cheaply too. With the transmission, screwing up has a much higher price tag.

We'll definitely flush the entire system, including the cooler and the torque converter. I was thinking the dye would be a way to be absolutely sure the repair was done correctly, but you're probably right that we don't need to bother. It took me a few months of wondering why I was seeing transmission fluid coming out nowhere near where transmission fluid normally is to realize that it was leaking into the final drive, but now I know what to look for.

Thanks!

-- Joe

[jangell]

About a week ago my friend and I pulled the transmission, rebuilt it in the basement, and we re-installed it over the weekend. Here's what we found:

The plastic tube that brings ATF from the gearbox part to the torque converter has some orange sealant that was clearly failing, and maybe a nicked O-ring. This is clearly how the ATF was getting into the final drive. We could have sealed it up again right there, but we decided to delve a bit deeper. The filter also looked very clean.

We removed the final drive and looked at the B2 brake and the C2 clutch pack. The clutch pack was in great shape, with only minor wear on the discs, but we replaced them anyway since we were already in there. The brake also looked very good, although there were some burn marks on the metal ring that sits on top of the brake, and on one of the metal brakes.

We were going to take apart C1, but we didn't have the tool to do it, and we were getting concerned about dealing in further than we really were comfortable with. That said, a modern plastic version of the tool is actually available on eBay for around $30, should someone need to do this.

We were also going to take out B1. We got the clip out, then noticed we had to take out something closer to the opening of the casing, and after much effort we got that clip out, and then realized that this is where you need another special too (basically a block and a threaded rod) to push out the rings. This is also when we realized we needed a special tool to put the clip back in. Since we didn't have that tool, we bought a 6" metal bucket from Home Depot, deformed it a bit to fit over the spring retaining ring, and used a press to compress it enough that we could get the clip back on. I'm sure we could have fabricated the other tool as well, but since the discs were in good shape we decided not to risk doing something wrong and not being able to get it back together again.

Everything went back in the car fine. We had a problem with not being able to get out of first gear, though. The solenoids were seized, but soaking them in a bath of penetrant overnight freed them up. Not sure how they got seized in a week, but whatever. A bigger problem is that we forgot to re-install the spindle that goes from the governor to the gears in the transmission, so it thought I wasn't moving and was just revving the engine. The governor had fallen on the floor and the spindle fell out, and we just didn't notice. Once it was reinstalled, it shifted just fine.

We also replaced the O-ring behind the driver's side output shaft, being careful to mark it and get the right number of turns to avoid ruining the pre-load on the differential. This O-ring was the weak point through which the ATF leaking from the transmission was eventually seeping out of the final drive.

The last thing we had to do was reseal the dipstick tube, which was annoying even with otterstat seals. We finally got it properly seated and sealed properly, though. Drove it home, and it works great. It doesn't seem to leak at all, which I think is a first for my car.

Thanks again for the help!

-- Joe

Some of the old rings. Some are in such good shape the writing is still visible on them.
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Another pair of rings, one old (the darker one)and one new.
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The one burned brake disc.
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The failed seal on the tube that carries ATF through the final drive.
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[David T]

First, I want to congratulate you for the courage to delve into places where most Delorean owners would never attempt to go. Second, I want to congratulate you on successfully fixing an automatic transmission. An accomplishment few can claim. Clearly you were not the first one to be inside, that sealant on the tube is not supposed to be there. Yes, there are a few special tools necessary to do a proper job but even without them you were able to get it done. A few suggestions. Cut the filter open and clean it or replace it. You cannot properly inspect it or clean it unless you take it apart. Do a line pressure check and adjust if necessary. Do all of the other external checks and adjustments and then check them again after 500 miles. Make sure all of the shift computer wiring is secured and away from the exhaust pipes. If you can get 500 miles on the transmission trouble-free you are probably fine and can go on to fix anything else that may need attention.

[jangell]

Thanks! I wouldn't have attemptedthisit without my friend (who is a professional classic car mechanic), and even he didn't want to go in here, and definitely didn't want to get far enough to replace the clutch packs. Honestly, it didn't look THAT hard to me (which really just means that I'm being unreasonably overconfident, or my friend just made it look easy :) ), and if we had the time I probably would have had us take apart enough to get to the other clutch pack and brake, but at this point I'll wait until something else goes wrong. Also, I should have my own lift in my new garage in less than 2 months and won't have to rent bays anymore.

I've put at least 100 miles on it so far, and it's been fine. There's sometimes a half second or so pause shifting between first and second, while there isn't any when going from second to third. It's not a real issue compared to how things could be, but I'm curious about it. We did make sure the electrical lines are clear of the exhaust (I have don't have the crossover pipe in mine, but the throttle cable to the transmission was burned though due to lying on the header, so that needs to be replaced, but we got it unkinked and out of the way for the time being until I can get a new one), and made sure it was adjusted properly (it was a bit loose previously).

I'll see if I can hunt down a J-21867 so I can do a pressure test, although it might have to wait until I get that garage and lift. Given what the diagnostic chart in G:05:03 says, maybe that slight delay from 1st to 2nd above is due to slightly off pressure, although I don't see other symptoms of mentioned there. Still, it should be checked.

I notice that DeLoreanGo sells new filters (while supplies last), so I'll see about picking one of those up, as well as a new silicone gasket from DPI (although they're reusable, mine has gotten to its limit from all the pan removals I've been doing, or so my friend says).

Thanks again!

-- Joe

[David T]

The delay may go away once it warms up. Check the trans fluid level as per G:04:02. Could also be the governor control cable adjustment. Might also be a problem with the shift computer. Replace the caps inside, very common for them to blow apart. Check the line pressure. Make sure the vacuum line to the vacuum modulator capsule is connected and not leaking. A slight delay is not a cause for concern as long as the shift is smooth.