Yamaha F90 Lower Unit to Leg Seal Leaking Exhaust

[AJ168]

I have an 07 F90/65 (Jet) that I've noticed has a small bubble in the aluminum leg where it would normally join to the lower unit. In this case, there is a spacer in between the jet volute and the leg. It is at the top of this spacer, port side of the motor where some exhaust gas/water is pushing through. It seems to be about at the right place where the exhaust tube runs down into the lower unit. I spoke with Outboard Jets about it, they think it's no big deal, but this is a Yamaha issue, not Outboard Jets. I'd love to pull that spacer off and take a look, but it seems that whenever I do any job for the first time near the jet volute, I end up breaking at least one bolt. From what I'm learning, it seems that one broken bolt per job is making out ahead. Is this something worth risking snapping more bolts and more machine shop bills to investigate?

 

[Bronlonius]

I had this same issue with my F25. If this is a similar design, it's a fairly big job to take it apart and will require about $100 in gaskets. You will end up pulling the lower unit, leg, oil pan, and powerhead to re-seal it. Basically, there are two non-reusable gaskets between the powerhead and leg, the bolts run into the powerhead and go through either the leg, exhaust manifold and oil pan. It's probably easier to explain how it all fits together if you look at an exploded diagram.

And yes, I had one bolt on the leg break on me. I left it alone and so far no leaks, there are 11 more so I don't think it will cause any problems.

 

[AJ168]

I'm a bit confused, I'm talking about the seal that would normally be the lower unit on a prop drive and the leg, nothing to do with the powerhead. The only difference with my motor is that I have a spacer between the leg and the jet.

Thanks,
AJ