Merc 75/90 ELPTO lower unit parts interchange

[dandreye]

Hi All,

The original lower unit that my 2000-01 Merc 90 ELPTO came with must be part number 1667-9011G57, let's call it old one. Looks like the same outboards dated 2003-04 onwards (0T627235/0P215669 and up) came with 1667-9011J15 that I just purchased as spare, let's call it new one. Detailed part diagram comparison reveals the following differences:

- driveshaft bearing: 31-42677A1 (Timken 15101/15245) in old one vs 31-883047A1 (Timken NP171520/NP570491) in new one. Any ideas what exactly inspired this change? Are these bearings interchangeable? A few scarce resources I've come across say they measure the same but I cannot even find NP171520/NP570491 on Timken's website - wondering if I could use 15101/15245 in new one if required?

- gears: those with 13:30 ratio in old one vs those with 12:28 ratio in new one. Again any ideas what exactly inspired this change? I understand the newer ones are somewhat tougher due to supposedly fatter teeth (besides a slightly higher ratio). Were there any failures or other issues seen with the 13:30 ones? Are they interchangeable too (obviously as a 3-gear kit)?


Many thanks in advance!

 

[tommarvin]

I don't know, but it sounds like your fighting the markets, Find a used lower unit and bolt it on.
Your used lower unit is out there, its going to take effort to find it in a nation wide search, then Canada,never give up every city on Craigs list, ebay,

 

[dandreye]

tommarvin:

I already purchased a spare 1667-9011J15 one. Just trying to understand if the parts mentioned in my initial post above are interchangeable with those for the older 1667-9011G57 one that's currently in use.

 

[tommarvin]

Im sorry, I don't know.
Get the whole complete lower unit that you just bolt on,
Its out there Ebay craigs list every city.

 

[dandreye]

tommarvin:

> Get the whole complete lower unit that you just bolt on

The 1667-9011J15 that I already bought recently as spare *is* exactly that (i.e. whole complete lower unit assembly) and I know for sure it's fully compatible with my OB. I just spotted some internal changes in it that I listed in my OP. Was wondering if anyone intimately familiar with internal design of the lower units for these OBs built during the timeframe in question is aware why they were necessary and whether those respective parts are interchangeable.

 

[Faztbullet]

Most likely it was beefed up due as it was used on 4 strokes......

 

[dandreye]

Faztbullet:

> Most likely it was beefed up due as it was used on 4 strokes......

Do you know which particular 4-stroke models and/or years? I just quickly checked all versions of 90 (4-stroke) and 90 EFI (4-stroke) and lower unit assembly numbers are all different from 1667-9011J15 even though they all look quite similar..