overdrive oil leak, what's this bolt/plug?

[ozzie alpine]

I have a slow but persistent oil leak from the rear of my overdrive.
It appears to be coming from this bolt/plug, next to the speedo drive but I'm not sure what it is and what will happen if I undo it... Does it locate/fix the speedo drive bearing or something?
It has a copper washer. It looks like it needs to be removed and re-sealed with some thread sealant and a new washer.

Gearbox/overdrive was a recon unit supplied by Jeff H a few years ago and is otherwise perfect.

Thanks,
Dave

 

[beamdream]

Location bolt for the cable housing, no big deal to pull the bolt and seal.

 

[RootesRacer]

I believe that retains the speedo gear assy. It should be safe to seal it with nonlocking thread sealer.

 

[Mike O'D]

This is a "face seal" situation - thread seal is not the right way to go. Either get a new copper sealing washer or take the current one off, heat it to red hot with a torch and immediately quench it in water to bring it back to dead soft temper. Put it back on, tighten it up and it should seal.

 

[puff4]

^ What Mike said. ^ Also, I would probably put a wee bit of Hylomar on both faces of the copper washer before installing it to enhance sealing and to help prevent galling of the aluminum against the copper.

 

[ozzie alpine]

Great, thanks everyone