Lower unit 1995 blackmaxx mercury 150

[msn26753]

I believe i lost my lower unit this morning.. When i give it gas it goes fine forward and reverse, but when i drop the hammer, above 2500 rpms, it jumps out of gear.. Rpms shoot up and boat goes no where.. Anyhow.. Does all the lower units interchange? It was a 1996 i believe xr4 6 cylinder 150 blackmaxx.. But i lost compression, and a guy in town had i believe a 1990 blackmax. Xr2 .. So he changed it over for me about 4 years ago.. I think its the same lower unit he just changed the block.. Anyhow, im in search for a lower unit, what do i need to be looking for.. Are they interchangeable? I think google told me the gear ratios are all the same and bolt patterns are the same, but i did see different shaft sizes.. Hmmm. Is the gears hard to change on the one i got, or should i leave this to a pro?

[silverbullet02]

Assuming it's a standard 20" motor you can use just about any lower unit from 1976 to present 2.0/2.4/2.5 mercury or mariner. You probably have 2:1 gears if it's from a 150 so you'll wanna look at that. The other very common gear ratio is 1.87:1. A lot of gearcases for those for sale on the boards here or Craigslist, Facebook, etc...

[msn26753]

Maybe my lucky day. . I was researching and didnt think about a spun hub. . Im gonna have to pull it off nd take it to prop shop to see. . It diesnt jump out of gear, its just the rpms shoot sky high and it doesnt move once i get into full throttle..

[EuropeanAM]

If you would, take a few minutes to review the Announcements at the top of the Forum, and be sure to provide the Required info when posting. Thanks!

Spun hub is definitely a wise place to look- as is checking the shift cable adjustment, and sampling the gear lube (in that order, as the spun hub would be simple and account for your complaint).

[msn26753]

Oops... My bad.. I will get serial number tommorow.. I am bring prop in to prop shop tommorow... Fingers crossed