Originally Posted by Nos4r2
Hmm... I wonder if you actually need it or if it's a bit of daft overengineering that can be removed to make life easier.
I like the Merc terminology for 'hit with a hammer' til it stops btw. "Install into housing until seated"
I did wonder that myself, but... In between the power head, this bush and the water pump, the shaft diameter has been reduced substantially. So, thin shaft with a thick lump in the middle probably needs a bearing to stop it whipping. Only an American could say why they've machined half the metal away. The full diameter would have been ok and the weight saving would be negligable, I'd have thought.
I'm going to replace it if I can (if I've got a heavy enough hammer) because I suspect there may indeed have been some movement in the shaft. The gearbox oil showed signs of water ingress and I'm wondering if the oil seals under the water pump are leaking. New ones come with with the overhaul kit.
American engineering never fails to amaze me, fascinating but sometimes pointless (NASA biro, USSR pencil), and then they cock up the good bits by putting a bronze bearing round a stainless shaft and expect it to work in sea water without any lubrication.
The bush is quite brittle, so I suspect it's a sintered bearing, with graphite or something included in it to make it 'self lubricating'. Mmm! I wonder how many others sieze up?