Where could this water leak be coming from, FZR?

[mittens]

Awesome man. I have had to reseal both Transoms on bot FZs I have had, and replaced a mid bearing on one. Not fun job but having a dry ski is a plus! Looks like you did a great clean job too.

[seabrook]

man great write up and pictures!!!!

[seabrook]

this should show for all that once assembled there is no reason to grease the mid shaft bearing assembly and the reason why yamaha removed the tube- pumping grease could actually damage the seal on the mid shaft housing

[Mr. GP1800]

this should show for all that once assembled there is no reason to grease the mid shaft bearing assembly and the reason why yamaha removed the tube- pumping grease could actually damage the seal on the mid shaft housing

there’s still a grease fitting. It’s just on the housing and you have to reach in and find it.

[RedG]

I will definitely be greasing mine with a very slow pump every 50 hours, I’m sure one of the reasons mine failed was because it was never greased even when I paid for the prepaid maintenance and the shop manual I believe says every 100 hours. In my opinion they were just too lazy to reach for it.

[mittens]

When mine failed the Rubber surround cracked, and water came from between the rubber and the metal. After rebuilding one, you realise you grease fills a void, and the brearing soe but not the seals like you would think... its basicly, a axle seal (Like the back side of a trailer bearing) On the inside, then the bearing. then another axle seal flipped toward the prop, then another one just like it again towards the prop, and then a Thrust washer with a rubber kirt. that's what is sealing the water out.

[TimeBandit]

this should show for all that once assembled there is no reason to grease the mid shaft bearing assembly and the reason why yamaha removed the tube- pumping grease could actually damage the seal on the mid shaft housing

Yeah, not feeling you on this one. Service Manual's periodic greasing schedule is good enough reason for me.

When mine failed the Rubber surround cracked, and water came from between the rubber and the metal. After rebuilding one, you realise you grease fills a void, and the brearing soe but not the seals like you would think... its basicly, a axle seal (Like the back side of a trailer bearing) On the inside, then the bearing. then another axle seal flipped toward the prop, then another one just like it again towards the prop, and then a Thrust washer with a rubber skirt. that's what is sealing the water out.

Correct.

Again, we are referencing the mid-wall IB unit (not the pump-tunnel mounted unit). Yes, It is very important to add grease to the Zerk fitting on IB housing ... as it adds grease/lubricates the unsealed ball bearing and the 3 seals all sitting there in the center of the housing. As mittens stated above, there are 3 axle seals slid onto the midshaft - one facing fwd of the bearing and two facing aft of the bearing. By the term "facing", we're saying to resist fluid passage toward the bearing, yet permit passage easily away. Thus, pumping too much grease into the bearing cavity via the Zerk will simply permit excess grease to ooze past those seals as each seal has a seal spring on the backside of the rubber allowing the seal to lift away from the shaft, while properly returning to a sealed position. Proximity of these 3 seals means they will naturally contaminate themselves with grease, and that is indeed by design, as the seal's rubber rides on the shaft (aka friction-zone) - yes just like a hub wheel on an axle.

Let's talk "keeping the water out" ... as there are two fundamental ways water can come into the hull via the IB unit.
First way, is the rear shaft seals. The two seals facing aft are water-tight therefore in-fact keep water from traveling along the shaft into the bearing area, and then past the fwd seal into the hull.
The next way is the IB housing seal, aka there is yet a 4th seal, and this might be what seabrook is referring too ... as it is a large rubber lip molded into the housing's vibration dampener body, and mates with the mid-wall partition. It does not "need" grease because unlike the shaft seals, it's not sealing against any moving/sliding surfaces. It is indeed an important seal, and yes, it does also function to keep water out. Often this seal fails when an oxidation of the aluminum housing causes a swell/blister thus deforming or cracking (as mittens stated) the seal from the mid-wall surface. So yes, water does reach that cavity between the housing and mid-wall, which meant getting past the thrust washer skirt (see next). FWIW, it's one of my personal pet-peeves, being a salt water rider, because that void is virtually impossible to flush regularly, and lends itself to that said oxidation/blister problem.

Finally, the function of the thrust washer / rubber skirt that fits over it . . . again, not meant to be water-tight, but rather to shield hydraulic forces in the pump tunnel from being transmitted to both the 2 rear shaft seals and that 4th IB mid-wall seal. Without this, hydraulic pulses could prematurely stress these seals to fail and "burp" water past them in violent changes within the pump tunnel - think jumping waves and throttle-chop pump-stuffing events.

[mittens]

^ awesome more detailed description.

one caveat. The leak I was talking about and had was the actual rubber dampener, separating and cracking from the aluminum mid-wall bearing housing... this leaking as well.

can be seen how bad separated here..

https://youtube.com/shorts/diud4U7R6As

[tman701]

Yeah, not feeling you on this one. Service Manual's periodic greasing schedule is good enough reason for me.

........ FWIW, it's one of my personal pet-peeves, being a salt water rider, because that void is virtually impossible to flush regularly, and lends itself to that said oxidation/blister problem.

I know this isn't feasible for everyone, but I have always tried to run in fresh water(river/canal/lake, etc..) whenever possible just for this reason. I don't think it is the answer but its better than nothing. My oldest ski that i just recently got rid of was a 95 raider and never had an issue with it. Greased midwall bearing every 50 hrs and apart from 99% salt water riding, I would sometimes drop it in a canal that was fresh water to give some sort of flushing to parts that wouldn't get covered when doing an on the hose flush. Like I said, not totally feasible for everyone, and not even sure if it works, but for me it did.

[TimeBandit]

. . . .
l rubber dampener, separating and cracking from the aluminum mid-wall bearing housing... this leaking as well.

Yup - thanks for pointing that out.
That is a common failure I forgot to mention: de-lamination of the rubber dampener from outer (or inner) aluminum housing.

Hey, all I gotta say is - it could be worse ... it could be a carbon ring (no haters).

I prefer the Yamaha engineering over something that, if ever fails (and I won't get into the fray on the statistics of it occurring) won't permit a sudden onslot of water to rush into the hull.

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tman701 - that is a great idea, and likely the best way (freshwater dip). Problem for me - I live 3 min from the nearest ocean ramp and 30-45 min from the nearest lake or pond. Granted, I'd go out of my way for an extended layup however.