350c transmission leak at speedo cable.

[leftylou]

My transmission is leaking around speedo bullet. The center o ring is sealing fine, it is leaking around the outside o ring. I have replaced the entire bullet, both o rings and the speedo gear twice and it is still leaking. I’m wondering if the o ring might be slightly under sized. Does anyone have a good source for the correct o ring? Or any other ideas why this may be leaking?

[geezer#99]

Is the transmission vent clean?

[leftylou]

I know very little about transmissions so o have to admit I don’t know what a transmission vent is much less the condition of mine. How would the vent cause the leak around the bullet? Would the engine need to be running for this to cause a leak? The truck is currently sitting and still leaking.

[leddzepp]

The vent is a tube on the top of the transmission, sometimes it becomes plugged and if so will cause excessive pressure to build up, which causes a leak.

[Rust_never_sleeps]

^^ if it leaks when hot, it may be the vent. If it leaks when cold, probably not

[leftylou]

It’s leaking when cold. I guess I need to try a third o ring unless anyone knows any trick to get this one to seal better.

[geezer#99]

Post a pic of the speedo bullet.

[leftylou]

Here’s a photo. The original is on top, the new one is on bottom.