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Fluid drive leak


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1941 Chrysler New Yorker, C30, inline 8.
The drip, drip onto the garage floor has become too serious to ignore any longer. The last time I started up to check to make sure I no longer had an intake vacuum leak (I didn't), I ran the engine for 5 or 10 minutes, all seemed good, and shut down, but then on the way out of the garage, noticed a shiny new puddle of about pint of oil on the drip pan. It's from the clutch/fluid drive housing pan, or at the very least the rear of the engine, except it's clean oil. Pulled the pan off and it's the dreaded fluid drive unit leak, and it seems to be from the middle of the unit, at the back end, toward the clutch, and not from either of the fill plugs. Drat. Wish me luck, it's all gotta come off and then ship off the fluid drive unit to a guru to install a new seal. I envision many weeks of a lot of parts on the floor. But hey, it's an opportunity to repaint the propeller shaft and replace mushy motor mounts. 


Questions: Can I replace the fluid drive seal myself, or is it best left to someone who has done a few of them? 
Is Andy Bernbaum still rebuilding these things with fresh seal kits? There was some other shop mentioned, in upper midwest, I think, who refurbished fluid drives?

Does anyone in northern California have the remainder of a recently purchased bucket of the magic Mobil 104743 DTE Oil, Light Circulating? 

How about a clutch alignment tool? Is that a truly necessary tool for getting the transmission and clutch all lined up and bolted up, or can I just struggle it together?

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The graphite  carbon ring has probably cracked and or the copper accordian bellows.

The job is relatively easy with the factory Miller tools.

I have done quite a few when I was working...not anymore.

I would not let anyone cut the FD open. They don't need to to replace the seals as long as the deep inner seal surface is not pitted or the surface not flat.

If the FD is cut open and re-welded you will most likely end up with some vibration. It cannot be cut open and welded back up as a typical converter. No accurate solid centering hub on the output side of the FD unit.

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  • 2 weeks later...

I am now well and truly into this job. It's most definitely the fluid drive leaking. Have pulled out the propeller shaft, and now the transmission. The prop shaft needs attention -- needs new U-joints for sure (cross-type U-joints for an 8 cylinder car are hard to find and $$$), and the slip yoke is pretty stuck, although it has moved a bit. I think I can get that loose and cleaned up and regreased with the help of a ratchet strap and a sturdy anchor point. The transmission slid out without too much difficulty. Now it is a large pile of parts on the floor, and I still have to remove clutch before getting to the fluid drive. When I ship out the fluid drive for repair, that will be some down time, so I will also replace at least the rear motor mounts while I have everything out, and there is a brake line which is now completely accessible, and heck, the brake master cylinder is now 20 years old, and it probably needs at least a rebuild kit. There's so much room under here with all this stuff pulled out. How do you know where to stop on repairing stuff? 

 

Transmission out. Thanks, cheap transmission jack. Third time I've used you. Not the best tool, but good enough. 

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There's really a LOT of oil in all the things. Transmission, overdrive, engine oil, and fluid drive (6 3/4 quarts for the 8 cylinder unit). There is a trip to the household haz waste drop-off facility in my near future. I've got some electronic junk to go, too. 

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There's a big hole where the transmission used to go. One bummer is the carpet nails sticking through the floor pan. I think I will be re-cutting this gasket myself, as I can't find a store-boughten one available anywhere. 

 

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I have the same transmission jack lol. It’s definitely a plus with that heavy transmission. Where are you sending the fluid coupling for rebuild? I have a 52 Coronet and I may need that in the future. Take your time and fix anything that needs fixing while you have the space especially any safety issues. Be aware that coupling is heavy and awkward and the nuts are not easily accessible. Keep us posted.

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Chrysleritis,

When I did my clutch I noticed a little bit of oil in the clutch cavity. I had my floor pan off. I checked my FD Fluid Level and it was full so I just did the clutch and tranny mounts.

I did my Drive Shaft U-Joints also. The one thing I wished I did was replace the Tranny Gaskets as well so - when the opportunity strikes you may as well do that as well.

I only say this because I have a drop of 10wt sort of dripping slowly out somewhere in the form of a dime size or so on the floor week after week of driving mine.

I haven't really went looking for the leak hard even though I just replaced my emergency brake band on my tranny this spring. I did buy a 2 gallon thingy of 10wt. oil 10 years ago for like $24 so I don't have to worry about adding a little to my tranny once a year. LOL. Be Safe!

Tom

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10 hours ago, chrysleritis said:

Transmission out. Thanks, cheap transmission jack. Third time I've used you. Not the best tool, but good enough. 

IMG_0613.jpeg.b00511b36614c7e7ca9a740318ee8da5.jpeg

 

That trans jack has a coupon for it right now.  Hope the link works

 

https://go.harborfreight.com/email/2024/05/e182731-61232/?uid=ea74137e7859c2aefa9f22b4018fd5b36da75c8bab83d2893ae5a41b64023220&infy=35957368385&bxid=35957368385&mi_u=35957368385&mi_ecmp=2024_06_02_wk2224_Free_Gift_0_60_ENGAGED

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Need a little info from Fluid Drive Whisperers -- anyone who has pulled one of these units out before. All the prep work is done. Large pile of parts neatly on the floor in the garage, fasteners sorted and labelled. I've pulled out the propeller shaft, transmission, clutch, clutch fork and throwout bearing, lower clutch pan, removed the oil pan, and I got those booger nuts off the studs that hold the fluid drive unit onto the crankshaft flange. Best tool: 5/8" flare nut wrench and a short cheater pipe. The manual says, "Remove drive flange stud nuts and pull fluid drive unit back free from crankshaft flange. ... After removing nuts, fluid drive and clutch driving plate may be withdrawn from clutch housing." The fluid drive unit will not budge and seems to be good and stuck on the crankshaft flange. Can I safely pry on anything, like between the studs and the engine block? Is there some trick to this? I don't think I wanna whack or pry on the fluid drive unit body with anything very hard. Any advice appreciated.  

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Best guess from the pics posted is a rubber mallet to the ring gear. Light to moderate thumps while rotating the drive and using a wooden 2x2 to apply light pressure other side of the drive.

 

If no else post something to help. You might try an air hammer to the flange in light trigger taps as you rotate the drive. This vibration through the metal from the hammer might help loosen the bond. Needless to say this is probably a last resort thing. 

 

Joe Lee

Edited by soth122003
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  • Solution

Leave one FD nut on one stud loose...

Use a foot or longer steel flat pry bar.

Wedge the FD rearward...wedging between the bell housing opening and the FD front face. It should/will pop loose. The nut is used to stop it from falling off the crank and killing you.

You do not remove the FD clutch driven plate just to remove the FD coupling...not necessary.

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Thanks, that was the technique. I got out "the good crowbar", and applying the principle that two objects cannot occupy the same space at the same time, you have to just persuade the crowbar to be where the other thing currently is. The fluid drive weighs 51 lbs, although it might still have a bit of oil left in it. Once it broke loose, I slipped the transmission jack under it to get it down and out without trying to heft the thing on my chest. This step concludes the teardown process and represents the point of maximum number of parts all over the floor, so it's all gravy from here. Now have to concoct a shipping crate arrangement to send it out to be re-sealed. 

 

Fluid drive, 1941 Chrysler 8 cyl.

 

The rear crankshaft seal is fortunately not the dreaded rope type, and is available as Best Gasket kit #3774, replacing Mopar #695786. 

Rear crankshaft oil seal, 1941 Chrysler 8 cyl.

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And now that it's been cleaned up in preparation for re-build, should the fluid drive unit be painted? It looks like there's some remnants of black paint on there, and if I mask off the important bits, should I spray it? 

 

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  • 1 month later...

Fluid drive unit was shipped out in June. It's in the rebuild queue, should have it back in a couple more weeks. I think I have finished the stage of the project where you clean everything. No small task. Very messy and time-consuming for the home mechanic, but I feel like I'm better, faster, and tidier at this than I used to be some years ago. I'm annoying my wife less with the greasy filth, for sure. While everything is pulled off the drive line, I'm gonna address several of the leaks. (Today I passed by a cruise meet-up of Pontiac GTO's and those guys were all comparing notes on how many drip pans they have on the garage floor.) I have a pile of new parts to put in, including the rear crankshaft seal, rear output seal for the transmission, pinion input seal for the rear end, new gaskets for the oil pump, new universal joints, new grease seal for the propeller shaft. The propeller shaft was a real mess, so that got blasted and repainted. Clean and re-grease the clutch torque shaft and all the linkages and cranks. Fresh clutch disk to replace the fully-greased one. Clean up the transmission case. See if I can fix whatever is funky with the shift rail and fork that makes reverse gear not want to stay there.

 

Propeller shaft before:

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Prop shaft yoke getting unstuck, which was bad:

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Prop shaft after:

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Transmission very dirty:

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And cleaned and painted. 

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It's the little-known R7B-1 overdrive. 

Feels like I'm making good progress

 

 

 

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  • 1 month later...

New motor mounts in! The previous owner or garage had installed the bolts in from the bottom, with the nuts on the top. Pro tip: it's very hard to install new mounts this way. It's much easier if you just bite the bullet and remove the floor pan so as to have access to the top of the clutch housing so you can get everything back into alignment. Old upper mounts were oil-soaked and gooshy, and one of the spacers was broken at the weld joint. Next up: replace speedometer cable with a NOS one I found in the pile of parts. I apparently bought it in 2005 for $40 and it is in great shape compared to the old one coming off. Replace parking brake cable -- old one has a broken strand that not only catches when you set and release the brake, but also catches me in the scalp whenever I shimmy under the car. Replaced pinion seal on the differential, and the transmission output seal. Parts are going back on the car. Fluid drive received back from rebuild. Now need to actually buy the magic fluid. And I think I need copper sealing washers for the fill plugs. 

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