Mercury Lower Unit Serial# and Model# HELP!!

[jsbelcher2001]

I am having some trouble locating my serial and model# for my lower unit. Its a 175 Blackmax. I already have the lower unit off and I do see numbers inside where the waterpump was sitting, but none of these numbers seem to match up. Im ready to get my boat back on the water and this is the only thing holding me back. I just don't want to order the wrong one. Any help on this would be GREATLY appreciated.

 

[mark]

mod and ser number are located on or near the trim plate on a omc the they are on the port side ( passenger side of the boat) i think # there covers the complete eng and lower unit hope this is helpful

 

[wrechin2]

It depends on what you need as to if you need to identify the case. It is rare that a older engine has the original lower because lowers will interchange. So a 1976 175 lower will bolt on a 2005 2.5L 200 engine. Ratio is incorrect but you get the point. So if you identify the year of your engine, doesn't mean the lower unit parts will be right. If you are needing internal parts, you can identify a pre-load case (early 85-back) from a non-preload (86-up) and then you can tell if it is a 90's case by the anode at the cavitation plate. Most parts are the same between the cases. What are you needing???

 

[jsbelcher2001]

Had a friend who knows more than i do stop by today and help me with what I needed and I have a new one ordered. It will be here this week.Thanks for the feedback guys, its greatly appreciated.

 

[wrechin2]

<p align="justify">New one what??? I have quite a few lower parts. If it is something I have a bunch of you are welcome to it. </p>

 

[jsbelcher2001]

I purchased the whole lower unit. Its has a 3yr no fault warranty. $850.00. From what I can tell this is a good deal. The reason I bought it is because the housing was busted on the one that I have and the fwd drive gear is bad. thought it might just be the clutch dog or the shift linkage needing adjusted but I found out different when I pulled the lower unit off. Noticed the gear oil had ALOT of metal shavings in it.

 

[wrechin2]

Yep, I installed a SEI outdrive on a Mercruiser yesterday. They hold up pretty well as long as you don't have a ton of HP or a very heavy boat and even worse when you have a combination of both. The internals are softer compared to a factory unit from what I am hearing because of the hardening process they use. For most applications they are fine.

You should have had a 1:87 ratio. This would have had 15 teeth on the pinion and 28 on the forward and reverse gears. If it was a 2:1, it would have been 14/28.