Leaking Transmission (TH400)
Thread Starter
Pro
Joined: Nov 2004
Posts: 659
Likes: 0
From: Flower Mound Texas
Leaking Transmission (TH400)
This problem has me pulling my hair out, which believe me I can ill afford. I have a turbo 400 auto tranny and I have a leak where the speedo cable enters the transmission body. I unscrewed the speedo cable housing at the leaking spot this weekend and I saw that there is no rubber seal of any kind on this. Because of the way the cable-connector housing is designed, I don't see how an o-ring would be effective since the housing goes over a flange on the cable and appears to seal steel-to-steel by pressure only. Thread-sealer would be ineffecitve for the same reason (though I tried it anyway). Any ideas how to fix this?
Le Mans Master
Joined: Aug 2001
Posts: 7,804
Likes: 4
From: Standing still with all my might Texas
Cruise-In X Veteran
St. Jude Donor '09-'11
There should be a very small orange o-ring in there around the plastic shaft that the speedo cable plugs into.
The seal is between the plastic output shaft (actually part of the speedo gear) and the transmission case. The part of the outer cable that threads onto the transmission is not intended to be a seal.
You should be able to buy the speedo seal at any chevy dealer.
The seal is between the plastic output shaft (actually part of the speedo gear) and the transmission case. The part of the outer cable that threads onto the transmission is not intended to be a seal.
You should be able to buy the speedo seal at any chevy dealer.
Tech Contributor
Joined: Aug 1999
Posts: 14,379
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
Actually, there are 2 seals. In addition to the inner shaft seal that Kevin mentioned (this seals the rotating part), there is also an outer O-ring that seals around the entire speedo insert to the case. The insert is retained by the bolt/clamp and you can remove the whole thing to change the 2 seals. You can get the seals from GM or from any tranny rebuilder.
Burning Brakes
Joined: Feb 2004
Posts: 958
Likes: 1
From: In the Beautiful Shenandoah Valley of VA
Originally Posted by lars
Actually, there are 2 seals. In addition to the inner shaft seal that Kevin mentioned (this seals the rotating part), there is also an outer O-ring that seals around the entire speedo insert to the case. The insert is retained by the bolt/clamp and you can remove the whole thing to change the 2 seals. You can get the seals from GM or from any tranny rebuilder.
Steve
cable, housing, leak, leaking, outer, ring, seal, speedo, speedocable, speedometer, th400, transmission
