Raw water pump

[Bluejacket]

I've looked over the previous posts and didn't see an answer for my issue.
Particulars:
1988 Yanmar 4JHE 44hp
water pump">Raw water pump isn't pumping. I took the impellor out and it looked like it just came out of the box. The brass key was not worn, there were was no wear or tears and all of the 9 blades were there. I had ran the engine without raw water for almost 20 minutes with no damage to the impeller. That would indicate that it wasn't spinning.
I greased it with Vaseline and reinstalled it. Worked great for a couple of hours and then stopped pumping again. I'm thinking that if it spun that time the shaft must still be intact.
Current plan is to replace the impellor anyway but curious if anybody else has experienced this problem.

[tkeithlu]

There was just a post on the same problem. In that case, the nut holding the pump shaft to the engine shaft under the pump had come loose.

If the auxiliary shaft coming off the engine were bad, you'd have serious and unlikely problems - a failure inside the engine. So, there's the connection between that shaft aand the pump shaft, as above. Then there's the connection between the pump shaft and the impeller, which you can test by removing the impeller, bumping the engine, and seeing if the shaft turns. Then there is the impeller itself. The bronze core may have spun relative to the "rubber" of the impeller. The problem is somewhere along that sequence.

I'll bet that you find it very quickly if you start at one end and test toward the other.

[Bluejacket]

OK !
Smoke'em if got em.
YOU can take the rest of the day off.
I had just come back in from running a bench test and
by greasing the rubber, I had reduced almost all of the friction and the impellor spun. But when the grease wiped out, the rubber dragged and....wait for it !
the bronze keyway had broken free of the rubber impellor.
Problem solved.
A $65 part vs a $750 pump.

[tkeithlu]

Congratulations! Lift a cold beer for me. It feels great when you actually track down something like that, and repair it cheaply.