Water Pump

The water pump on this A4 has not pumped water very well. I replaced the impeller with one I found in the boat that was the same size as the old one before the first start attempt. The old one had taken a set (bent vanes) so I knew it would not work. After pulling the cover on the pump about 6 times I decided it was time to remove the pump for diagnosis on the work bench. Anyone who has seen my work bench understands how big a deal this is for me, but I just shoved all the other shit to the side.

I have all kinds of ideas on how to proceed from the Moyer Marine (Specialize in Atomic 4) and their forum. Some suggest soaking the impeller in Marvel Mystery Oil so it will swell a bit. It does measure .002 inch too narrow. I'll buy some MMO tomorrow. Don't ask what's in it because it's a mystery. Another suggestion is to take a few thousands off the face of the pump with a belt sander to bring the worn chamber back to tolerance when you put the cover on. This has got to be more difficult than one might think, just sanding the pump evenly, haha. If it works it saves about $250 for a new pump. If I can get the pump to pump about 5 GPM I won't mind spending a few $ for new seals and cam shoe.

I did run the engine today (with low pressure flow from garden hose) and it runs great after the carb cleaning. Today I remembered to check the transmission. Forward and reverse both worked but with a little vibration so I'll be posting about truing the prop shaft to engine soon.