1988 Mercury XR4 Black Max 150

[Rebel9921]

Hello..

Im currently in process of rebuilding my boat and currently have the motor in my garage... sort of cleaning/inspection/rebuilding if necessary...

So far... everything looks great... but the lower unit has a "T" shaped crack... short crack is abt 2" while long crack is 3"

I would like to know my options for replacing the lower unit??? or would some TIG welding be feasible as an option? If not, would the lower unit have to be very specific for this type of motor? or would I be able to use Alpha I or Bravo lower unit gear housing?

I know the OEM nbr is 1655-9572 C and the serial number starts with 0B28

Please let me know of my options regarding this... Pic is below

Many thanks

[fyremanbil]

They can be welded, but it's better to replace it. If the gearcase is beat up or needs to be resealed, I wouldn't invest any money in it. All the gear cases from the 2L, 2.4L or 2.5 will work.

[j_martin]

The original gearcase is smaller, and thus more slippery in the water than the full sized gearcase. It uses a smaller diameter prop and the gear ratio is a bit higher at 1.78:1\

They are a bit weaker than a full sized lower. Run fully submersed and well maintained. When subjected to the forces of surfacing a 3 blade prop, they tend to have a fairly short life.

All the 2.0, 2.4, and 2.5 gearcases bolt interchange.

The engine behind me in the picture is a 1988 XR4.

Personally, I wouldn't spend much money on that one.

hope it helps
John

[Rebel9921]

What I meant to ask would be this: What would my options be regarding upgrades to a better lower unit for the XR4? Do I have to find the original lower unit that came with the XR4 or would it be possible for me to find one with different gear/larger gearcase??? If thats possible, then what type/kind of lower unit would work as an upgrade???

Thanks

p.s. John... do I know you from fm.com??? your signature line is so familiar???

[j_martin]

What I meant to ask would be this: What would my options be regarding upgrades to a better lower unit for the XR4? Do I have to find the original lower unit that came with the XR4 or would it be possible for me to find one with different gear/larger gearcase??? If thats possible, then what type/kind of lower unit would work as an upgrade???

Thanks

p.s. John... do I know you from fm.com??? your signature line is so familiar???

All the gearcases from the V6 2.0, 2.4, and 2.5 lines will fit. You can use any one of them. Most of them are 1.87:1 gear ratio, and they take a prop with a larger hub.

There's a couple of us that would rather fish than work. I was born to fish, but I'm forced to work.

John

[T-REX]

My xr4 had a small geercase an wanna say 1:78 geerz......Could be wrong on tha geerz, been too long...But it wuz a small case...

[Robertrosen]

Don't even bother with the smaller case, just get a standard 4 3/4" case, they will last much longer. I blew up my original case a few years ago.

[capnzee]

Was that unit leaking or had water in it? Did it freeze? Run in salt water? Looks like it. Any of the Merc V6 units should fit. You probably have a 20 inch mid-section. Once you pay for new seals, welding, labor etc you may be better off just surfing the S&F parts for sale. May find one of 500 bucks?? or start checking the Merc dealers junk piles. Capnzee

[Rebel9921]

So if I wanted to buy a lower unit housing for Mercruiser motor, an Alpha I housing... would that work??? as long its for a 2.0, 2.4, or 2.5 V6??? Would the prop/drive shaft, gears, etc from the XR4 lower unit work in Alpha I housing or would I have to buy new parts n etc???

Capnzee- No idea... someone said it looked like freeze stress crack... Im from Minnesota... so no salt-water here... the boat was all fresh water... All I know is that the boat/motor has been neglected for over 9 years... been sitting at a Marine dealership since my brother dropped it off in 1999... and I finally got it out of there last spring... been focusing on the boat lately... now winter is here... want to focus on the motor...

[capnzee]

Minnesota?? that baby froze to death. No, I don't think you can put any I/O lower unit on that boy, but maybe, with a drive-shaft change,gears? I don't know but somebody on here will. Why not KISS? probably cheaper in the long run.

[Rebel9921]

Yep that baby froze to death due to improper winterizing/maintenance... she has been suffering for the past 9 years but... all the work Im investing into her will be worthwhile... she'll live and purr again!!!

I believe Im going to go for the XR4 Lower Unit Housing from Ranger 976 and just move everything from the old lower unit into the new one... of course, I'll replace all the o-rings, bearings, seals, n etc... that should work...

Thank you all for your help!!!

[Capt.Insane-o]

Be sure the castings are the same # there is two. .the 247 case and the 972 case. The pinion bearings are different.

[Rebel9921]

So basically, everything from the 972 case would fit the 247 case as long I switch out the Pinion bearings???

[capnzee]

Capt. Insane-0. I am a Navy veteran from the Vietnam era, I am a republican, I voted for John McCain. I believe in free speech and guns but I think your representation of Obama 08 is in extremely bad taste and totally out of place on Scream and Fly. I have read a lot of your posts and you seem like a pretty "heads up" kind of guy please reconsider! Sorry for jumping on this thread--I apolgize to all but I felt it had to be said and not in a P.M. type of way.

[Capt.Insane-o]

Yep that baby froze to death due to improper winterizing/maintenance... she has been suffering for the past 9 years but... all the work Im investing into her will be worthwhile... she'll live and purr again!!!

I believe Im going to go for the XR4 Lower Unit Housing from Ranger 976 and just move everything from the old lower unit into the new one... of course, I'll replace all the o-rings, bearings, seals, n etc... that should work...

Thank you all for your help!!!

Outside diameter of the bearing is different between the two, along with the driveshaft. The casting #'s are in the space between the exhaust reliefs on the top of the case. Last three #'s.


Capn I'm tired of seeing the word Obama in my posts too. Still makes my stomach turn. Untill I find something more suitable it stays. I thank you for you concern and service to this country.