Muncie M-20 Leaking Fluid
Thread Starter
Heel & Toe
Joined: Dec 2006
Posts: 18
Likes: 0
From: Somerset KY
Muncie M-20 Leaking Fluid
My 68 BB has an M20 (1965 year code) that shifts great but every time I drive the car fluid leaks from the front and rear seal (which were replaced this spring) and from all 3 shifting linkages and even the speedo hookup. I had it out this spring and like I said earlier replaced front and rear seal and changed out old gear oil to Lucas gear oil that met GM viscosity requirements. 2 weeks ago changed back to Valvoline but tranny is still leaking as before. I am in the process of pulling tranny again. I've searched forum and seen mention of seal kits. Also fluid level is and was well below the fill hole. It seems like the thing is under pressure but the fluid level has always been well below the fill hole. Anybody else had this problem??? Fixes?? Thanks.
Le Mans Master
Joined: Mar 2004
Posts: 7,500
Likes: 1,508
From: Little Rock AR
The counter gear shaft hole goes through the lower front portion of main case. Some times the hole gets worn and the fluid leaks from there. Some people have luck with silicone sealer there but this is not a perfect solution and does not work all the time.
There is no front seal on the input shaft on a Muncie. The front bearing retainer has a gasket but it is not typicaly a leak source. The most common source of leaks are at the shifter shafts, countergear shaft opening, and the rear output shaft seal AFAIK. The gear oil may be leaking and blowing around. It might be that it just looks like it comes from somewhere else and apears that it leaks from the front. There is a creative "fix" for the shifter shafts if that is determined to be the source of the leak. If that is part of the problem, let me know and I can post it.
Hope this helps.
-MArk.
There is no front seal on the input shaft on a Muncie. The front bearing retainer has a gasket but it is not typicaly a leak source. The most common source of leaks are at the shifter shafts, countergear shaft opening, and the rear output shaft seal AFAIK. The gear oil may be leaking and blowing around. It might be that it just looks like it comes from somewhere else and apears that it leaks from the front. There is a creative "fix" for the shifter shafts if that is determined to be the source of the leak. If that is part of the problem, let me know and I can post it.
Hope this helps.
-MArk.
Heel & Toe
Joined: Sep 2007
Posts: 22
Likes: 0
The counter gear shaft hole goes through the lower front portion of main case. Some times the hole gets worn and the fluid leaks from there. Some people have luck with silicone sealer there but this is not a perfect solution and does not work all the time.
Hope this helps.
-MArk.
Hope this helps.
-MArk.
