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Question on 1977 evinrude 25hp water pump

C

chrisgt

Contributing Member
I have a 1977 evinrude 25hp (model: 25703S) and my OMC manuals only go back to 1981, at which point they had apparently switched to the stupid plastic housing with stainless insert.

This outboard has the single piece cast water pump housing but what I am not sure of is whether or not it should have gaskets between the housing and the backing plate, and the backing plate and the lower unit??
It was glued together with so much silicone that I'm thinking i should take the water cover off to make sure the engine isn't clogged with the stuff, but what i want to know is: How should this go back together? Really light application of RTV to make sure it seals? Just put it together with grease? Is there a gasket that I'm not finding?

This is the pump in question:
kRQtlOS.jpg


Thanks!
 
Thanks! I'll clean it up real well and throw i back together with a new impeller. Couldn't be happier with this thing; free engine with 135psi in both cylinders and, after some TLC, runs like an absolute dream. I didn't realize there was a gap from 77 to ?? where they went to CDI ignition but didn't move straight to the plastic thing.

I have seen a lot of the plastic pumps melted, probably from people running them dry, but the metal pump housings used in mercurys tend to have far fewer problems. I guess they are cheaper to replace, so that's always the trade off.
 
Plastic pump housings melt because people invent new ways to destroy them.----And the new generation / boat owners simply do not know the boating basics.
 
The only time i have ever damaged one on a personal engine was by making the mistake of loaning it to someone who i thought wouldn't destroy my stuff, so... I tend to agree.
 
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