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| A904 leaking, what to check https://slantsix.org/forum/viewtopic.php?t=68168 |
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| Author: | Eatkinson [ Fri Apr 18, 2025 4:06 pm ] |
| Post subject: | A904 leaking, what to check |
My 63 Dart wagon has the A904 auto trans out of a 64 Dart that works well when the fluid is leveled-up and has the added benefit of the '64 and up in-pan filter, but is obviously quite unhappy when the majority of the ATF leaks out all over a hot exhaust pipe. This has been an ongoing, long-time issue that needs solving once and for all, as long as it's not horribly involved. I've already replaced the transmission park lock cable because of a melted outer jacket (that was not a fun job). I've also changed the o-ring in the park lock valve body and used a little blue Permatex to help stop drips from that location. Again, not a fun job, I don't have a pit, OR a lift, so it's creeping under the car on jackstands for me. None of my prior efforts have solved whatever is the most significant ATF leak. Where else would fluid be leaking from? I did see a drip at the bottom of the torque converter dust cover when I was under the car last. I looked at the shift cable, and saw no evidence of fluid seepage there: that looked dry and dusty. Appreciate the guidance, thanks. |
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| Author: | Reed [ Fri Apr 18, 2025 9:15 pm ] |
| Post subject: | Re: A904 leaking, what to check |
Input shaft seal Output shaft seal Dipstick tube seal Neutral safety switch seal Kickdown shaft seal Speedo cable gear housing seal |
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| Author: | MDchanic [ Sat Apr 19, 2025 4:26 am ] |
| Post subject: | Re: A904 leaking, what to check |
Not to state the obvious, but is it the pan gasket? Charrlie_S was selling some factory modern ones at a good price, not sure if he has any left. If you're thinking about dropping the pan anyway, you might want to drop him a line. Working on a transmission on your back is an SOB, especially at the age you probably are. If there's absolutely, positively no way to get the car up high enough to really get under there (buddy with a lift, shop owner who likes old cars?), I would recommend doing something rash to clean it up. like jacking it up in a place you don't normally go / work, and expending several cans of the good, nasty carb cleaner spraying the crap out of it (and not getting it in your eyes), so you can maybe trace the leak. GUNK or similar is an alternative, but won't get as much crap off of it without the sort of scrubbing you can't do with your limitations. Good luck! – Eric |
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| Author: | Reed [ Sat Apr 19, 2025 10:30 am ] |
| Post subject: | Re: A904 leaking, what to check |
Quote:
Input shaft seal
ANd the trans cooler lines and fittings.Output shaft seal Dipstick tube seal Neutral safety switch seal Kickdown shaft seal Speedo cable gear housing seal I have taken ramps to the local coin op carwash and used the engine degrease function to use hot water to pressure wash the trans before. Just do it late at night. |
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| Author: | MDchanic [ Sat Apr 19, 2025 12:01 pm ] |
| Post subject: | Re: A904 leaking, what to check |
Quote:
I have taken ramps to the local coin op carwash and used the engine degrease function to use hot water to pressure wash the trans before. Just do it late at night.
Good idea. I never thought of that one.Of course with any high-ish pressure washer, be careful that you don't drive grit INTO bearings and closed areas.  – Eric |
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| Author: | SlantSixDan [ Sat Apr 19, 2025 1:29 pm ] |
| Post subject: | Re: A904 leaking, what to check |
Quote:
My 63 Dart wagon has the A904 auto trans out of a 64 Dart that works well when the fluid is leveled-up and has the added benefit of the '64 and up in-pan filter, but is obviously quite unhappy when the majority of the ATF leaks out all over a hot exhaust pipe.
The majority? Yoof…that's a big leak. Reed's list is a good one. The kickdown shaft seal was a culprit in my '62. I never got around to fixing it; guessing the new owner (in Australia) probably has done by now. But if you're talking about trans fluid on the exhaust pipe, that still puts the park and/or shift cable at the top of the suspect list. Quote: I've already replaced the transmission park lock cable because of a melted outer jacket (that was not a fun job).
No, it isn't, at either end. Quote: None of my prior efforts have solved whatever is the most significant ATF leak. Where else would fluid be leaking from?
Power-clean the underside, get and deploy this, drive the car a bit, then make with one of these. That'll guide you right to the source(s) of the leaks.
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| Author: | Eatkinson [ Mon Apr 21, 2025 2:43 pm ] |
| Post subject: | Re: A904 leaking, what to check |
Quote:
The majority? Yoof…that's a big leak.
Perhaps I should have chosen my words more carefully. The leak is slow~ish but faster than I'd like. It takes time for the majority of the fluid to leak from wherever it is, but eventually transmission performance is noticeably impacted. And it is leaking on the exhaust pipe which makes for a smokey situation.Quote:
But if you're talking about trans fluid on the exhaust pipe, that still puts the park and/or shift cable at the top of the suspect list.
Noted. The replacement park lock cable I went to a good deal of trouble to install was a "good used" one, not a new one, which makes me question how "good" it really was.  Quote:
Appreciate this. I'll get on it.
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| Author: | Eatkinson [ Mon Apr 21, 2025 2:44 pm ] |
| Post subject: | Re: A904 leaking, what to check |
Quote:
Input shaft seal
Thank you. This is quite a list. How many of these are easily inspected with the trans in the car, I wonder? Trans cooler lines and fittings are all new, so there's that.
Output shaft seal Dipstick tube seal Neutral safety switch seal Kickdown shaft seal Speedo cable gear housing seal |
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| Author: | Eatkinson [ Mon Apr 21, 2025 2:49 pm ] |
| Post subject: | Re: A904 leaking, what to check |
Quote:
Not to state the obvious, but is it the pan gasket?
Nope, I failed to mention I had cleaned underside and replaced the pan gasket with the Chrysler pan/gasket Dan recommended on one of his informative posts.Quote:
Working on a transmission on your back is an SOB, especially at the age you probably are.
I'm not yet over 50, but yes, working on one's back under these non-high-riders really stinks. Thanks.
... Good luck! |
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| Author: | Reed [ Mon Apr 21, 2025 10:15 pm ] |
| Post subject: | Re: A904 leaking, what to check |
Quote: Quote:
Input shaft seal
Thank you. This is quite a list. How many of these are easily inspected with the trans in the car, I wonder? Trans cooler lines and fittings are all new, so there's that.
Output shaft seal Dipstick tube seal Neutral safety switch seal Kickdown shaft seal Speedo cable gear housing seal |
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| Author: | Greg Ondayko [ Tue Apr 22, 2025 6:46 am ] |
| Post subject: | Re: A904 leaking, what to check |
Sometimes I have had the Neutral Safety Switch / Reverse Switch itself develop a leak through the electrical connector. When it is old and suspect I replace them. If yours is a push button / cable shifted transmission the kickdown / throttle shaft seal might be different than on the transmission with a linkage shifter / kickdown. There is a tool that is made to remove and replace the shift shaft seal on 1966? and newer type cases that do not have the cable shifted mechanism. I used it on my 77 Ramcharger with a 727. That truck Had plenty of room, It would certainly be tight to do that replacement on an Early / Narrow A Body. I was able to replace every seal on my Ramcharger except for the input shaft seal which it did not need. I finally did get it pretty dry and clean under there. Lots of engine de-greaser and power washing helped. I also Removed the Skid Pate for cleaning and replaced the failing Transmission / transfer case mounts too. Good Luck, Greg |
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| Author: | mcnoople [ Wed Apr 23, 2025 1:17 pm ] |
| Post subject: | Re: A904 leaking, what to check |
What I use whenever I have a difficult fluid leak is a product named "met-l-chek D-70". I tried to find a source on here to link it, but was unable to find it. I was only able to locate the full kits which are pricey and we only use the D-70. How it works in fluid leak detection is simple. You have to very carefully clean and dry the suspect component. Then you just spray everything with the aerosol spray can. It leaves a white chalky powdery residue on anything you spray it with. Then you run the component and see what starts getting damp from the fluid. It is an official honda(car) required product for a few recalls so if you are friendly with a local dealer tech they might be able to hook you up, or their parts department might be willing to sell you some if they can even figure out to order more of it. For years I have considered buying a can of "right guard" deodorant and testing to see if it would work in the same manner. It is basically a spray powder that evaporates and leaves behind the solids, so a heavy solid deodorant might serve the same purpose for the rough and dirty world of old cars. linky for any that want to see what D-70 looks like, apparently it is a european company so the overseas crowd might have an easier time getting it. https://met-l-chek.com/product-category ... evelopers/ edit: the very nice list of potential leaks left off one that is rare but does sometimes happen. There is a gasket that seals the front pump housing to the front of the transmission case and can mimic a front seal leak. |
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| Author: | slantsik [ Mon Apr 28, 2025 1:43 am ] |
| Post subject: | Re: A904 leaking, what to check |
My 2 c extra. Also check the pan bolts. One may have stripped threads. Some muppet overtightened mine and stripped the thread ,causing lack of compression on that part of the pan and a resulting leak. |
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| Author: | Greg Ondayko [ Mon May 05, 2025 7:28 am ] |
| Post subject: | Re: A904 leaking, what to check |
Quote:
Also check the pan bolts. One may have stripped threads. Some muppet overtightened mine and stripped the thread
Friendly Transmission Mechanics' eh
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| Author: | SlantSixDan [ Mon May 05, 2025 11:27 am ] |
| Post subject: | Re: A904 leaking, what to check |
Bunson Honeydew: "Who left those pan bolts loose‽" Beaker: "Meeeeeeeeeeee!" |
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