Leaking TH350 Speedo cable

[81cutlass]

I was sick of my trans leaking like a bp oil rig so I finally got around to tightening the speedo cable. My trans has always leaked and ive traced it down to the the speedo cable and somewhere else. I cleaned off all the sand from the cable and ended up breaking the plastic speedo cable housing. Got a new one but now the cable nut doesnt quite tighten the cable down all the way. And Im too afraid of tightening it down too far as I have a feeling I am goinng to break it again.

I am assuming I am missing a gasket or something for how bad it leaks. The only gasket I have is a small rubber part that fits between the inner cable and the plastic speedo gear housing. Doesnt look like it would seal much of anything. Im thinking theres a gasket that sits between the cable and the plastic housing but I can't find a part number or anything. Is there actually a gasket there or does it just seal from pressure and I just have to tighten it up and hope I dont snap the plastic threads off again.

 

[Longroof79]

There also should be an O-ring around the driven gear fixture. As for the center seal, you're right, they usually don't seal that well. I've replaced it and it still tends to leak.

 

[rustyroger]

Is the transmission fluid level correct?, might be worth checking the breather to see if it's blocked as well.

 

[81cutlass]

Yeah I ended up finding out that a '69 John Deere 4020 tach drive cable gasket fits perfect and seals the hole up 100%. I havn't leaked a drop out for the past few days and it put a gasket in a spot that GM should have.

Agriculture parts FTW! 😀

 

[rustyroger]

Good tip to remember 8)