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I run a ’64 RDS-26 (on salt) that has that style of box – the dealers had given up on getting it pumping properly when I bought it from them. Whilst it had a new impeller, no effort had been made to clear out the passages from the pickup tube, nor the channels that appear into the base of the pump ( both were almost completely blocked). The pump housing and area underneath was badly pitted too and looked like it’d chew up impellers over time. It all needed a lot of work before I found a NOS pump housing here. I worked hard with dental picks etc, at clearing everything from the skeg pickup, to the area under the pump, until it was clean. It really does pump properly now, but I can only assume that it was getting a small enough amount to show willing then run out as the water in the pickup passages depleted. Hope the pics help. Have also shown a ’63 Big Twin I had that has a different style of screen.
My spare box is the ’67 version on that dropped the screen & passages and relied on a pickup tube from skeg straight into the back of the pump housing. After ’71 they used a revised pump design with a single pump to powerhead intake design which possibly could be modified (am in the middle of a move with the 71 box buried in the chaos, so I am not sure the bolt pattern is the same..). Am sure there’s better experts than me here, who might be able to advise.
Fleetwin,
I knew about the ice damage concerns from a blocked weep hole, but your crack doesn’t seem like a place that could ever trap water. Even if it somehow did I would think it would just stretch the intake plate out before the casting split.
I know you were suggesting a cracked or corroded casting creating a direct path for exhaust into the water pump. I did not find any evidence of that.
With the gearcase leaking badly enough at both the shift O ring and the driveshaft seal, the exhaust path could be literally through the gearcase.Since there is no real harm in doing it, I’ll get the motor put back together and mounted on my boat for a lake test. I’ll change the oil again right before I launch and I wont stay out long.
Rapier,
Wow, crusty. This motor had no blockage in the big water channels and none of the white AL oxide buildup inside. It may be that the salt exposure to this motor was so little that it should not be considered a factor here.Fleetwin,
I knew about the ice damage concerns from a blocked weep hole, but your crack doesn’t seem like a place that could ever trap water. Even if it somehow did I would think it would just stretch the intake plate out before the casting split.
I know you were suggesting a cracked or corroded casting creating a direct path for exhaust into the water pump. I did not find any evidence of that.
With the gearcase leaking badly enough at both the shift O ring and the driveshaft seal, the exhaust path could be literally through the gearcase.Since there is no real harm in doing it, I’ll get the motor put back together and mounted on my boat for a lake test. I’ll change the oil again right before I launch and I wont stay out long.
Rapier,
Wow, crusty. This motor had no blockage in the big water channels and none of the white AL oxide buildup inside. It may be that the salt exposure to this motor was so little that it should not be considered a factor here.Agree…The crack shown in frank’s picture is not from freeze damage….I’m pretty sure it is just common weakness in that casting, which is why it was changed slightly in the later 60s. I suppose anything is possible, is there evidence of gear lube in the impeller housing cavity?
You mentioned you don’t see any cracks/erosion in that intake path, so perhaps it is best to return to “square one” now…Reassemble, put the engine on a boat in the water and try it….
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