HPDI Prop Shaft Seal still leaking after replacement

[SkeeterJohn]

I have a 250 HPDI and over the winter i replaced all the seals. I was still getting water in the gear oil so i did a pressure check and turned out i needed new prop shaft seals.

I replaced the seals but when i pressure test i can still hear air escaping from the new seals. What gives? i've installed both seals with the lip facing outwards. The air seems to be leaking around the prop shaft itself and not around the housing.
Any ideas? Surely not a worn shaft as it looks fine with no visual signs of damage. The air leaks even without turning the shaft.

Thanks in advance i'm stuck!

[Shoalcreek]

Shouldnt the seals be back to back. One facing in and the rear facing out? One holds oil in and the rear water out.

[SkeeterJohn]

According to the manual they both face out.

[Nutoy]

How much air pressure did you use? Too much pressure and the seals will not hold

You are correct. All the double seals in a HPDi lower have the lip facing outwards.
During operation, HPDI's will leak a minute amount of lower lube. Over time, and left unchecked, the lube level can become dangerously low.

You'd think Yamaha would put something in the owners manual about this, but they didn't.
I've seen many HPDI lowers fail due to extremely low lube levels. Bearings are the first to go. Once a bearing comes apart, the pieces will take out the gears.

I run my HPDI almost daily and check the lube level at least once every two months. I usually takes 10-12 pumps to top it back off.

[SkeeterJohn]

I've been having issues with water getting into the gear case but not a small leak a significant leak. I tried resolving this over the winter replacing the drive seals and shifter seals. After doing a pressure test the prop shaft seal was hissing and spraying water on showed a leak. Thankfully I've managed to keep an eye on it and make sure at the very least i drain and fill with new gear oil. It's odd though because it seems to leak around the shaft itself and not the housing

I guess at this point i'll run it again and drain to see what is getting in now. when you open it and water runs out it's significant.

[mrdeath]

I've replaced my prop shaft seals twice, and my shift and drive shaft seals too. It will hold air, but still gets a little bit of water in it over time. I check it every couple of months, and replace it if it looks too bad. Never had just plain water come out when I drain the fluid, but it's always a little off colored so I can tell it's getting some water in it.

[SkeeterJohn]

I'll run it for a day and change the oil and see what is still getting inside. Hopefully changing the seals has helped somewhat even if they still may be leaking air i'm stuck on what the real issue is. I don't see how a seal would wear the prop shaft to the point where it doesn't seal very well. Doesn't make sense to me.

[pnut]

How much pressure are you using, I put 14, have you tried pulling a vacuum on it? I just changed my prop and drive shaft seals. No water intrusion but I always am a couple ounces low on oil when I check it. I guess that's where it's going to stay.

[SkeeterJohn]

Pressure over 10 doesn't seem to hold i haven't tried a vacuum on it instead.. it's refilled with lube now so i'll likely run it and empty it to see what ends up inside.