Lower Unit Replacement

[BassCatKWG]

Hello All,

2010 BassCat Puma FTD DC

2010 Mercury Pro Xs 250 (ser# 1B764965) (app. 700 hours)
Fury 25p 4 blade (at the moment)
Fury 26p 3 blade (sometimes)

My lower unit on this motor has quite a bit of play in the down shaft, enough to were it is starting to rub on one of the journals through the mid section. I can see where the shaft is rubbing and there is some aluminum dust present. Been like this for a while, noticed it last water pump (impeller) change a year or so ago. Has run fine since then but I know it needs to be addressed and now I think I hear a slight knock coming from it.

My question involves what type of lower it is. It is painted black and I'm pretty sure original to the motor.

1. Is this a Torque Master or were all those painted silver?
2. Should I just rebuild?
3. If it's not a Torque Master would I see any gains by buying a new or rebuilt Torque Master?
4. Any of you know any reputable places to get a reman Torque Master? Crowly?
5. Would love if you have time to chime in Don!


Thanks in advance for any and all responses!

[Savage]

Post a picture of this journal.
What is the diameter of the prop shaft?

[JOE54]

you better check yo mtr mounts for breakage, no way drive shaft should move enugh to contact exh housing

[Savage]

^^Yep^^ I'm confused by the "journal".

[BassCatKWG]

Sorry for the terminolgy. What I am referring to is the hole that the drive shaft goes through on the top of the driveshaft housing. It has been over a year since I dropped the LU so I dont have pictures and I don't know how much more rubbing there is now. Gonna drop it again asap. Other than a little sluggish on hole shot it has ran fine this past year. I just remember when I noticed it I knew something isn't right. I will measure the driveshaft diameter when I drop it. What mounts should I check JOE54, the power head to driveshaft housing bolts, or the actual transom/jack plate bolts?

I also noticed that I have some play in the prop shaft, seems like a little more than it should be. After 700 hours I know I need a rebuild or a new LU anyway. Just need to know what my options are, wanna get it right and if there is anything to be gained by spending a little more I am fine with it.

From the manual I have it seems there were 3 choices? Standard, TMgen1, TMgen2? I think mine may be the TMgen1 (when compared to pictures in the manual)

[Jtreed99]

Are you talking about the top of the lower unit? Once you drop the lower and remove the water pump housing there should be a driveshaft seal there and not a hole? It sounds like you may be talking about something different or you are discussing the top of the pump housing where the driveshaft exits?

[BassCatKWG]

The rub is at the top of the exhaust housing from what I remember. Definetely a ways up the shaft from the pump housing. I have never pulled the exhaust housing but its for sure rubbing in there somewhere. I've replaced the whole water pump assembly (housing, seals, impeller, etc.) a couple of times.

[Jtreed99]

If it’s very near the splines I guess it could be the crank shaft seal or the little o-ring dirt seal. Otherwise I don’t see how this could happen unless something in the midsection had come loose. I would suspect something else moving beside the driveshaft I think you would have other issues.

[BassCatKWG]

Thanks Jtreed99, gonna try and pull it apart to investigate further tomorrow. I will get a pic of the dirve shaft wear and post it.

[BassCatKWG]

Okay, finally got some time to drop the LU. It appeared to be about the same as last time I pulled it. The rub spot, which isn't very visible, is below the spline (pictured below). There is some endplay in the prop shaft and the drive shaft. Put it back together and ran in a test tank. The noise I'm hearing I can best describe as a random tick or chirp. Happens every 8-15 seconds and sometimes will be 1 chirp/tick, other times multiple. I used a mechanics stethoscope to try and isolate. It is definitely more pronounced at the bottom of the power head where the crank shaft travels through, which leads me to believe maybe the lower crank bearing is failing. A friend of a friend who is a certified Merc mechanic told me that while not impossible, he has seen very few crank bearings fail on the ProXs, especially at 700 hours. Hmmm. Thoughts?

We then discussed the possibility that maybe the sound is traveling up the drive shaft from the gears in the lower unit. I considered taking the lower unit back off and running the engine without the drive shaft for a minute or so to see if the noise disappears but with the exhaust sound and not having any load at all (driveshaft) this procedure may be a waste of time? Thoughts?

He told me to run the p*ss out of it and see what happens, and that they are prone to making strange noises! I'm not sure that is the remedy I am looking for, lol.

Anyways, I know I am going to at the least need a new LU. The prop shaft has way too much endplay (probably 1/8th inch or more), especially when compared to my friends that have the same engines. The main thing I need help with is identifying what LU I have. The research I have done is quite confusing. I have the 90-8M0071433 factory manual. It says 3 were offered. Standard, TM gen1, and TM gen2. I have also read that it may be a Verado gearcase. Hopefully one of you awesome humans can please shed some light on this for me with a part number perhaps? and, maybe a good place to purchase said LU.

My plan is to put a new one on and see if the noise disappears. Thoughts?

Attached are pics of the current one.

Again, thank you guys oh so much.


1.jpg2.jpg3.jpg4.jpg5.jpg6.jpg

[angle iron]

I believe Bass Cat would have rigged a Torquemaster (Gen1). Verado will work and be cheaper but will be a little less stable above 75.

[BassCatKWG]

Thanks Angle Iron, so you think maybe the gearcase has been changed, or are the pics I sent a gen 1 TM? I bought the boat from a pro that bought it new. I have an envelope of all the service invoices and do not have one that shows lower unit change. But, you have helped me come up with something I didn't consider, I will call Bass Cat (talk to them all the time anyway) and see if they can provide any insight. And also to mention, she can get a bit squirrely in the mid 70's. Thanks again!

[Savage]

I think you condemning a lower unit that maybe perfectly fine. I would run the motor with the lower unit removed, by connecting a water hose to the water pump supply tube.

[angle iron]

Did you measure the prop shaft?

[BassCatKWG]

Yes Savage, I am going to do that tomorrow. It does seem really loose though (endplay), especially in the prop shaft. And Angle Iron, do you mean diameter? I will measure that tomorrow but I think its the smaller diameter. Im thinking it is the Verado488 gearcase. Or possibly the standard optimax gearcase, which supposedly isn't rated for the Pro XS, although some folks use them because you can get a new one for $1999, lol. I talked to BassCat and they said more than likely it was the Verado case on a 2010.

[angle iron]

The Verado has stronger internals than the gen1 Torquemaster and is less expensive. The Torquemaster has 1.25” shaft.

[BassCatKWG]

Prop shaft mics .94" so I woukd say its a 1" shaft.

[BassCatKWG]

Ran motor without lower unit. Exhaust was so loud its hard to tell if it was still making that noise or not. Even with the stethoscope could not really tell.

Can anyone verify if my lower unit is part# 880686A43

That is the part number that ****.com and ****.net shows but when I search for that part number *****.com and a few other sites clearly state "not for XS/XB mdels."


This shouldn't be this confusing, lmao!

[EuropeanAM]

The gearcase shown in the pictures above is a VERADO-STYLE gearcase. This MATCHES the Serial Number.

There should be NO endplay in the propshaft- it is shimmed in both directions.

880686A43 is a direct-replacement for the current gearcase.

When in doubt- See Rhonda's Post (pinned at the top of the Forum) for Parts Ordering or Identification assistance. We don't promote the others you listed (here).

[BassCatKWG]

Thank you Don! And ya, I think its pretty worn out. Has quite a bit of endplay and radial play.