2.5 Gearbox

**chubsta** · 01-09-2021, 11:21 PM

In the process of cleaning a stripped 2.5 gearbox.
The manual states that the thrust washer behind reverse gear and the bearing carrier can only be installed one way.
I have measured the washer and cannot see any differences.
Can someone explain which way it has to be installed and why.
The manual doesn't explain it in detail.

**billybob** · 01-10-2021, 10:22 AM

It is supposed to be a tapered thrust washer, with smaller end going into bearing carrier. The newer service manuals, don,t specify that. So install it either way.

**rock** · 01-10-2021, 11:24 AM

What's up Bill? I think what he is talking about is the washer tween reverse gear and carrier that squishes o-ring. Never heard of it being directional or being called a thrust washer.

Rock

**billybob** · 01-10-2021, 12:40 PM

Yea ROCK I think you are correct. I was referencing to the small thrust ring between reverse & the clutch dog. The large thrust washer that compresses the o-ring should have 1 side bigger than the other. I have 3 of them I just looked at. 1 has an obviously bigger side, the other 2 it is not obvious with my old eyes. I just stood them on end, and watched what direction they fell. I would say that would be the smaller side. I,ll bet mercury just decided not to spend the extra time to build that washer with a beveled outside diameter, and stopped doing it somewhere along the line.

**rock** · 01-10-2021, 01:35 PM

It's because it is punched out a plate and not cut or machined. Most likely Merc wants the wider side against the machined area inside the front of the gearcase for maximum support. As many of these things as I have seen over the years I had never considered this being an issue and my guess is it will work either way. Just one more ideal than the other.

Rock

**TEXAS20225** · 01-10-2021, 01:41 PM

the tapered big washer disappeared a few years after that was put in the early manuals it no longer applies unless you have a tapered washer in your possession then put long side towards oring as that is its application to seal off oiled side of case to the water/exhaust side of lower unit i love momma merc changing part numbers without changing the part

or in some cases vice/versa

**chubsta** · 01-11-2021, 02:17 AM

Thanks for all the replies.
If the edge where the thrust washer sits up against is chipped will the bearing carrier still seal ok.
I read somewhere if the edge is damaged the case is a throw away job.
Is this correct.