1951 Plymouth P23 Transmission output spline leak

[51 Cranbrit]

Hi everyone. I'm new to the forum. I've seen a lot of very helpful information here on some of the issues with my '51 Plymouth, and this is my first post. Trying to get all leaks stopped on the 3 speed manual trans. Only issue I haven't figured out what to do about is the "seep" of oil past the output shaft splines on the 3 speed manual of a '51 Plymouth Cranbrook.

Background: I still have the drum off and trans is off the car. 19 years ago I put a new rear seal on and I've seen a lot of discussion about that. Only 2000 miles on the car since then. All I could get years ago was a seal from NAPA (15620) that is only about 1/2" deep as compared to the original seal being about 3/4" deep. Also the new seal design does not have a separate felt seal that the original did. NAPA says it is the correct seal, that they changed the design to eliminate the felt. The original felt seal went toward the exterior to prevent entry of dirt. Now I'm wondering if the replacement seal not extending as far into the bore (because it's only 1/2" deep) might cause extra oil to be "sucked" into the splines. There is a special heavy washer, exterior tooth lockwasher and nut that is bolted to 100 ft-lbs to secure the brake drum to the splined output shaft.  There is no sealant, the washer is just "crushed" to the flange and oil could seep past it. Hopefully I'll attach a diagram. Looks like they wanted a little oil to get in there to lube the splines. There is no seal to prevent oil getting down the splines. A new flat washer (has 2 notches pressed into it) is nowhere to be found. I've thought about putting some RTV Ultra Grey in there upon reassembly. There was only enough oil "weeping" to be able to see it after the drive shaft joint was removed. Everything else was dry in that area including the transmission body, the rear seal area, everywhere dry except just a dribble inside the cavity housing the large nut bolting the drum to the shaft.

Any thoughts welcomed. Thanks. Please advise if I should do different in my posting....

-Jim

[dpollo]

The seal is doing its job but   oil is moving along the splines.   It does happen but not all that often

.Some sort of sealant applied to the splines or the back of the washer may be the solution.

[P15-D24]

Did you check the sealing surface on the brake drum? If worn it may need a speedy sleeve to get the seal working correctly.

[51 Cranbrit]

Thanks Webmaster. Yes I did check that sealing surface on the brake drum, there is a "ring" there where you can see the lip was riding, but not bad, it cleaned up nice with crocus cloth. That area was surprisingly dry. The bit of oil "weeping" out was in the drum cavity in the diagram where the big nut and washer is shown bolted to the shaft. Only way oil could get in there is down the splines. And it was just enough to notice, maybe tipping the transmission when moving it around caused it to creep out.

Thanks Dpollo. Just what I was thinking, I have Permatex Ultra Grey to apply there. Any thoughts on a more appropriate sealer?

Attached are pics showing drum area upon trans removal (looks oil-free), seal wear ring on drum (looks very dry in there as well), lastly the spline cavity and the special notched washer that gets flipped over and locked into the drum splines. The cavity in the last pic is where the oil was creeping out, but obviously not enough to go very far, as shown in the other pics. I did no cleanup of oil prior to pics except in the spline cavity in the last pic. I'll look into the speedi-sleeve option - Thanks

 

[P15-D24]

When the transmission is level isn't the fill hole lower that the output shaft?

[Dartgame]

when I rebuilt my trans I used a speedy sleeve, new seal, and then cleaned the splines on the output and the drum. I put a thin layer of silicone on the washer and put it together. No leaks. Be sure to allow 24 hrs for the silicone to cure. Silicone cures with moisture from the atomosphere so in a closed space it takes a long time.

Edited November 20, 2017 by Dartgame

[51 Cranbrit]

Yes it is! For some reason, I was thinking during operation, part of the mainshaft would be in oil, but it isn't. Thinking more about this, there was no oil in that area upon initial disassembly, I would have seen that. So I believe the reason for a bit of oil to show up there is that I've been transporting/moving the trans around and tilting it so much that enough excess oil has drained back into the rear to migrate a tiny bit out the splines. Reason for removing the trans was to address a significant leak down the front, which turned out to be the countershaft hole, which I did do with a high quality RTV after thoroughly cleaning. Oddly, the gasket doesn't cover that countershaft hole, and it isn't counterbored for an expansion plug, and it sits well below the oil level. Think I'm all set, I hope to update this post with results after reassembly/operation. Thanks all for the great input.

[dpollo]

an expansion plug such as the one used on the lower shift rail will fit this hole.  The hole is slightly tapered so the countershaft will seat tightly with no leaks.

It MUST be removed through the back otherwise the reassembled unit will usually leak at this point.

[51 Cranbrit]

Thanks everybody. I'm going to thoroughly clean splines, put Ultra Grey silicone on washer, and no speedy sleeve cause no problem there. I'll try a 3/4" welch expansion plug in the countershaft hole after thoroughly cleaning the hole. Maybe somebody knocked the countershaft through the front for repairs before I owned the car. On Youtube I found 2 great manual transmission guides put out by Chrysler in the late 40's. Search on "Chrysler Master Tech Troubleshooting in the Transmission" and "Chrysler Master Tech Transmission Fundamentals". Thanks All.