Shift Shaft Seal questions

I agree 100%, there should be no added pressurization of either sump from other factors. If there is any tendency for fluids to leak in one direction or the other, it would be due to hydrostatic pressure (due to their relative heights) and viscosity (resistance to flow) of each oil . I believe the resting engine oil level is higher than the gear oil level and the engine oil is most certainly less viscous, so if the fluids wanted to swap space at rest, I'd put money on the engine oil wanting to get into the gearbox.

Somewhere I have it written down which direction the cups on the seals are supposed to face for a 308/328 but I can't find it. Pretty sure it was cups facing into the engine on both seals, which may line up with the hydrostatic pressure and viscosity theory I just pulled out of my butt (curse of being a mechanical engineer).

 

Maybe this might also help.

https://www.unobtainiumsupply.com/Downloads/Service%20Procedures/Quad%20shift%20seal%20installation%20tips.pdf

cheers, BB

 

Assuming all parts and tools are on hand and a modest level of mechanical competency, what is an estimated time to replace the shift shaft seals?

 

It was a full day job for me, but as usual for old cars I found other things to fix while I was under there! I used the Unobtainium seals and they were a little hard to install. No leaks since, and that was five years ago. But otherwise pretty straight forward if you like oil dripping on your head

 

Pressure or no pressure is not the question here. The cup on the seal always have to go against the fluid (Pressurized or not) you want to avoid going past the seal. The cup is designed in such a way that the higher the pressure that's exerted on the cup the more it seals. There will always be a differential pressure across a seal between compartments....In this case it's admittedly very low and mostly caused by hydrostatic Coolum and the friction in the oil vent system.

Best, Peter

 

It took longer for me to replace the shift shaft seals because I had to take out the center console. No matter how I tried to angle the engine, I couldn’t get the shift shaft to come out of the engine without binding on the selector rod and the selector rod only has very little clearance in the chassis hole. Further, I’d probably stay away from the cup style seals on the outside of the swage washer. Reason being, whomever installed them on my car previously and the seal ended up sticking to the shaft so oil would dump out the front when the seal would pull away from the front of the case when moving the shifter.

 

Its a good seal design and should not be condemned because some idiot couldn't replace them correctly. What you suggest shouldn't be possible.

 

Maybe dump oil was a bit exaggerated. The shift shaft boot was full of oil and leaking pretty heavily from there. When I pulled off the boot, the seal was out of the block entirely. The swage washer was still there so they tried to just put it on the end, which I would suspect was never flush with the outside of the block. When I had my wife move the shifter, the seal would slide back towards the block where the swage washer was located. Now, was it ever properly pressed into the block or even the right size? I’ll never know. Trying to place the cup seal on the outside of the swage washer was rather what I was condemning, not the design.

Beyond the foregoing, I’m not sure what you suggest shouldn’t be possible.