Help with F90TLRD Lower Unit

[Pbailey15]

I thought I would change out the water pump for my brothers motor. Never been replaced since new, has 350 hrs on it. Drained lower unit and the lube was thick and dark. I would say it was down about half capacity. I bought the full kit and the two drive shaft seals.

Did have one of the bolts snap from corrosion......had to center drill it until I could use a pick to get it out, all good no damage to threads. I did take note of the grooves worn where the seals seat and attempted to seat the seals so they would ride a new spot. Finished it up and ran it for 10 minutes in gear. Water at tell tale.

Checked lower unit for water and its getting in. All milky when drained. Took the lower unit back off and disassembled. There was very little thick white residue inside the pump in places, but I'm thinking now that was from the grease during assembly, maybe.

Made a pressure tester from a pump with gauge. Pumped it up empty of lube slowly to 15psi and the prop shaft seal started leaking. Upon close inspection there was some fishing line snagged in the spring in one spot on the outer prop shaft seal. I could pump to 8 psi and it would hold for a bit. I couldn't hear any air at top side seals.

I removed the outer prop shaft seal and found more line between the two seals and more at the inner prop shaft seal. So....obviously be changing those. My question is I'm not sure if water can get in the lower unit through those seals while running on muffs. I don't have a manual and its possible those seals were holding dispite the fishing line and I blew them with too much pressure. I'll get it figured out, but I sure would appreciate any thoughts/help before I go throwing parts at it. Does anyone one know the test pressure for a 2005 TLRD lower unit?

Thanks

[Pbailey15]

Been searching and I see folks use pressure and some vacuum for testing lower units. Which is correct and can anyone provide a test value?

Have new seals and lower water pump housing on the way, current one has some corrosion and just makes sense to replace.

Any help would be appreciated.

[Pbailey15]

Orders new drive shaft seals, prop shaft seals, lower pump housing and o-ring. I got a service manual, but it didn't clear up a question I have.

Where, how do the seals ride in the lower pump housing? Is the upper one installed all the way onto the shoulder shown in pic 1? Is it left down so it doesn't block any of the hole shown in pic 2? Do you install them touching each other or with a gap between? I would guess a gap.......

Same question on the prop shaft....touching or gap?

Thanks.

[Pbailey15]

Pic 2.................

[TownsendsFJR1300]

I had the two top seals replaced in my F150, (hadn't leaked yet but one SS spring on one seal failed).

I watched the master tech pressure test mine.

Drained my week old LU oil out, pumped up to I believe 15 PSI to see if it would hold for I beileve for 15 seconds. It did. That was two years ago. I just changed the PU oil about a month ago, nice and clean..

Just checked my Yamaha service manual, states 10 PSI pressure for 10 seconds...

[Pbailey15]

Just checked my Yamaha service manual, states 10 PSI pressure for 10 seconds...

I picked up a manual since that post and it says 14.2 psi for 5 seconds. That's an OEM manual.

I guess I'll install the seal above the hole and install the seals NOT touching each other, both drive and prop shafts.

[99yam40]

Yamaha has installation tools for setting the depth.
If you do not have the tools then you should measure how deep they are set before removing so you know how deep to set them

[Pbailey15]

Yamaha has installation tools for setting the depth.
If you do not have the tools then you should measure how deep they are set before removing so you know how deep to set them

Afraid of that, but already took apart. This is the second time around so where they're set now is probably incorrect and why it leaked.

If its critical, then I'll take it to someone who has the tools for assembly.

[Pbailey15]

Dropped it off at a local dealer with new lower pump housing. They called today and said it was ready to pick up. Held 15psi for 15 minutes. I suspect corrosion on the lower pump housing. But I'll never know for sure.

[TownsendsFJR1300]

Dropped it off at a local dealer with new lower pump housing. They called today and said it was ready to pick up. Held 15psi for 15 minutes. I suspect corrosion on the lower pump housing. But I'll never know for sure.

They replaced the SS water pump cup or the entire lower unit case/housing?

[Pbailey15]

They replaced the SS water pump cup or the entire lower unit case/housing?

When I started this I purchased the water pump kit, included were gaskets, SS cup, o-ring, woodruff key and bolts.

[TownsendsFJR1300]

Ok, just the pump kit.

It sounded like the entire lower unit housing was swapped out... Thanks..

[Pbailey15]

Ok, just the pump kit.

It sounded like the entire lower unit housing was swapped out... Thanks..

The item in the pics above is identified as a lower water pump housing in the parts break down. That wasn't included in the kit and it had corrosion on what I would call the spigot and some on the gasket surfaces.

[99yam40]

I have seen this too.
it is the drive shaft seals housing, have no idea what they call it a water pump housing

[TownsendsFJR1300]

The item in the pics above is identified as a lower water pump housing in the parts break down. That wasn't included in the kit and it had corrosion on what I would call the spigot and some on the gasket surfaces.

Ok, got it. The housing is usually plastic, could of overheated and warped, etc..

The bad pump housing shouldn't have let water in the LU oil. I gather they installed the verticle shaft seals you already had?