Another lower unit question

[MattVT18]

Engine serial #2B114981

I swapped out my prop last week, and as I usually do once the new one was on I gave it a spin with my hand. There was a muted "growl" that I had never heard before. I slowly rotated the prop a few more times and while it felt smooth there was still a faint noise. Pulled prop and decided to drain oil. When I pulled the drain plug water gushed out, not a few drops but a decent amount...enough to really concern me. I had just got back from a fishing trip about 30 minutes before swapping the prop so I don't think that much water got in there on that trip. I'm sure there is a leaky seal or two. My main concern is the noise. If this water has been creeping in since my last service in May 2024 I'm willing to bet some bearings are not in the best of shape and that's the noise I'm hearing. Replacing seals isn't a big deal, but bearings look to be a different story, especially when shimming, backlash and preload gets figured in if it's something near the front of the gear case. My first thought was to replace the seals for the shift rod, new water pump and shaft seal and maybe replace the entire carrier and "hope" the noisy bearing was the big one pressed in the back of the carrier.

I don't like guessing...my engineering and maintenance career drives me to identify the problem and make the proper repairs not just shotgun it. I'm confident in my mechanical abilities and have done everything outlined in the service manual for rebuilding the lower on various cars/trucks/tractors over the years but at the end of the day I'll have a decent amount of money in specialty tools and such plus the cost of parts that I'm not sure it's worth really digging into to repair. I'm getting prices for everything now and will see how much I'll be in it if I go that route. I've called a few shops/mechanics and none are interested in lower unit work past seals/water pumps.

I found a good used lower unit near me for $1k. Came off a blown 2008 225 Optimax. The guy is pretty sure it's a 1.75:1 ratio with 20" shaft. Would that lower work on my engine? He says it should be fine as he's done it before. Seems like a straight up guy and a couple of good friends have vouched for him being honest. I have no idea what lower unit is on mine, may or may not be original as I bought the boat used almost 2 years ago. Most 250 Pro XS Optis I see have the silver gearcase but mine is black if that matters. Any ideas or suggestions are appreciated.

[JOE54]

does your have 1;25 dia propshaft with cambered trailing edge of skegg that would be a TORQUE MASTER , will his work sure it will may drive lil diff , lasting who knows hard to say

[MattVT18]

Joe - not sure what my prop shaft is, thanks for the info to possibly know what I've got. Kinda kicked around buying the used one and then tearing into my old one as a project. Priced some rebuilt units online for $3-4 k, new ones are north of $5k. If I wasn't about to build a new house I'd upgrade to a 4 stroke.

[JOE54]

new TORQUE MASTERS are north of 9k , does you gearcase use a solid metal hub kit???

[MattVT18]

I've determined I have a Verado style lower on there right now. Same guy who has the first used one I mentioned also has a Torquemaster for about $2k...it's not the 2nd Gen with the funny wing deal so we think it'll work for me. I ordered a couple of tools to open mine up and at least see if I can tell whats making the noise. If it's more than something with the carrier I'll probably put it back together and get the used Torquemaster.

[lpugh]

upper drive shaft bearing is the first without proper lube, this is not a do it yourself job, get a used TK1 or Verrado unit for it.
I good remanned unit is over 5 k these days and a nee TK 1 just over 12 k

[MattVT18]

lpugh - that was something I was interested in as far as first to lack lubrication.

With the lower unit in neutral, the only thing spinning would be the prop shaft right? That's what made me think the bearing for the reverse gear or the tapered shaft bearing might be the culprit since they should definitely see motion and are low enough that if water had been in there a while they would probably be partially immersed. I could be wrong about all of that though.

At any rate, something is wrong with mine and I don't feel comfortable running it. From what I saw in my service manual shimming and setting backlash are the most technical part and I've done both in differential repairs. In the end I'll probably buy a good used lower and piddle with my current one to try to learn some stuff.

[JOE54]

in N everything spins accept the propshaft with engine running propshaft spins when clutch is engaged by shifting , buy the used and explore

[MattVT18]

in N everything spins accept the propshaft with engine running propshaft spins when clutch is engaged by shifting , buy the used and explore

I should have been more clear, engine off just me turning the prop nothing else should be spinning, right? I get a hollow growl/hum when I give the prop a spin. It's always had a little noise but it was worse when I swapped the prop the other day. That's what triggered me to drain it and I found all the water.

[MattVT18]

https://youtube.com/shorts/GeoZMudos...6OQOPcshLjaj5a

Short video of the sound

[lpugh]

bad bearings

[MattVT18]

As soon as I spun it I thought "that sounds like some rough bearings." Going to pull it off the motor tomorrow. Might pull the carrier to see what that reveals.

[JOE54]

bearings failing +1

[EuropeanAM]

FIRST AND FOREMOST: If it had water in it, and you drained the water, it then had AIR and OXYGEN. Ferrous metals + Moisture + Air/Oxygen = Corrosion/Rust. You need to refill that case with OIL or GEAR LUBE as soon as physically possible to stop or halt this process in it's tracks.

Your gearcase likely needs bearings at this point- it could be more but it could be that simple. If you don't follow these steps, you'll probably end up buying a gearcase anyway.

We build these all the time... as long as there's something left to work with.

[MattVT18]

FIRST AND FOREMOST: If it had water in it, and you drained the water, it then had AIR and OXYGEN. Ferrous metals + Moisture + Air/Oxygen = Corrosion/Rust. You need to refill that case with OIL or GEAR LUBE as soon as physically possible to stop or halt this process in it's tracks.

Your gearcase likely needs bearings at this point- it could be more but it could be that simple. If you don't follow these steps, you'll probably end up buying a gearcase anyway.

We build these all the time... as long as there's something left to work with.

I refilled it immediately after discovering the water. Have confirmed at least two bad bearings so far...