Refitting gearbox

[paddlers]

Going to refit the gearbox on my early 90's 135hp Mariner. Done a welded repair on the cavitation plate. I noticed that there was a ridge of sealant along the ridge separating the exhaust and the impellor housing and also that the plastic tube exiting the impellor appears to be a slack fit on the tube coming down from the engine!
Any tips ?

[Turbodiesel]

The white plastic tube is just a guide to help line up the pump hosing and the water pick up tube. Once its up tight the sleeve just sits loose on the tube. The silicon is just to seal off the exhaust gases from causing any coolant/exhaust problems.

[paddlers]

Thanks for that. The old plastic tube was in pieces so I bought a new one thinking it was part of the system from Bill Higham, cost me a fortune . It was only a couple of dollars in the states!!
Do I need to coat the mating surfaces of the rest with anything or just make sure of a good bead of silicone between the exhaust and the impellor housings?

[Turbodiesel]

Just a small bead of silicone, dont go mad otherwise its hard to get off next time!

[paddlers]

Thanks, appreciate that.