TH400 leak around speedo drive

[496bb]

See what you guys think. Pretty sure this is the source of some small leakage from my trans. 1987 R20 Burb w/TH400 and 454. Is this something that I can repair myself or need a trans shop for? If I can, what would be required?

 

[Edelbrock]

If that one drop is all that has leaked in the last 30 years, then you don't have a problem. How much fluid are you losing per month?

 

[Matt69olds]

If that one drop is all that has leaked in the last 30 years, then you don't have a problem. How much fluid are you losing per month?

That’s an easy fix. You need the O ring that goes around the speedo housing, and the small seal that goes inside the housing that seals against the speedo gear.

Go to your nearest transmission shop, chances are the builder has a box of those seals. If not, they are cheap to buy new.

The housing is held in place by a single bolt. If you raise the back of the truck, you will lose very little fluid. The outer o ring is obvious on how to replace, the inner seal is retained by a small clip.