700R4.output shaft leak

[texasmike]

The slip yoke on my driveshaft has a cap at one end with a hole in the center. The hole on the outside is about a 1/16” and much smaller on the inside of the cap. What is the hole for and could it be the source of an occasional fairly large fluid leak? There is nothing wrong with the output shaft seal.

 

[Ricko1966]

The slip yoke on my driveshaft has a cap at one end with a hole in the center. The hole on the outside is about a 1/16” and much smaller on the inside of the cap. What is the hole for and could it be the source of an occasional fairly large fluid leak? There is nothing wrong with the output shaft seal.

That hole is to let it breathe the yoke slides in and out it needs to have an air release to slide in and out freely. Otherwise I see the potential to draw and trap transmission fluid in the cavity at full extension and then force the tailshaft forward with hydraulic pressure from the trapped fluid when you hit a bump. As it is it draws air and expels air.Does this leak only happen if you park the truck for extended periods?

 

[texasmike]

Yes, but the extended period is never more than 4 or 5 days. I figure the input shaft o-ring has probably failed and is allowing fluid to flow where it shouldn’t. I thought that maybe the hole had been there to center the yoke for machining. I have seen some videos where they suggest plugging the hole.
Thanks for your help.

 

[Ricko1966]

Yes, but the extended period is never more than 4 or 5 days. I figure the input shaft o-ring has probably failed and is allowing fluid to flow where it shouldn’t. I thought that maybe the hole had been there to center the yoke for machining. I have seen some videos where they suggest plugging the hole.
Thanks for your help.

Fluid level should never be that high,unless the converter is draining back.

 

[Goldilocks77]

I have a 700R4 in my 77 C20. My driveway is an upward incline towards the garage. I always have to back the truck in to park it for longer than a few minutes. That way the transmission is angled downwards with the output shaft facing upwards. If I pull in straight with the output facing downhill, I risk coming out and finding a very large quantity of transmission fluid draining down the driveway. It only happens occasionally and only when parked uphill. Gotta know her quirks, I suppose. Sure would be nice to fix that leak tho.