Interesting. Mine isn't exactly new, but it also doesn't prime well sucking from a bucket or even after motor sailing on starboad tack with too much heel for an instant - especially at low engine rpms.
I'm curious to know if other J/30 folks have had the need to get a new pump body, and if so, after how long?
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Clean up the pump shaft so that the impeller slides on smoothly. If you have to tap it in, it will not center in the cavity and will either not prime, or will be hard to prime. Been there, done that and I have 40 years as a boat mechanic.
+1 to Last Fling's comments. If the impeller was previously forced on the shaft and was not fully seated, the pump cover may be scored after use resulting in extra clearance, so it won't prime.
Guys, No one appreciates your knowledge of these boats more than me. But in this case we need to work on some basics. This 'old' pump was fully rebuilt with everything but a new shaft and pump body. The shaft did not have any fins or wear to impede the installation of the new impeller. I did clean up some discoloration near the shaft seal. There was nothing unusual about the shaft itself. New bearings fit tightly and the new shaft seal went on without difficulty. The backing plate was new too along with a new gasket. The impeller installed without any great effort, I did not beat it onto the shaft, it is soft brass and it seemed to fit pretty well and was not overly proud of the pump body when I put the cover back on. The cover installed without any weirdness like if the impeller were not fully installed on the shaft.
I have never rebuilt a pump like this before, but I have more than a bit of mechanical experience. If something was odd about the way I rebuilt this pump it was not some obvious thing. What none of us here have are the specs for the dimensions of the body, the little squeeze piece or the shaft itself. It is these combinations of tolerances that make these pumps work. For sure if the combination or any one particular spec is too far out the pump is not going to work or work very well.
I think the key detail here is that here on the river the water has a fair bit of abrasive silt in it. This is evidenced by the 7 mile long sand bar at the mouth of the Columbia River. It would be almost worth the time to carefully tear apart the new pump and detail the critical dimensions and record them for posterity. Another possibility is that I burned the new impeller up by cranking the motor for nearly a minute before it started and then since it wouldn't prime it ran for another couple of minutes before I shut it down. At which point I started checking every connection for a leak and found none.
Other important details are that while the pump when primed from above did push water through the motor, the flow rate with the new pump is nearly double that with water at or below the pump level. Nobody wanted the old pump to work more than me, but the new pump does exactly what it is supposed to do and I suspect it will do so very reliably.
When I have time I will tear the old pump apart again because I want the bearings and the shaft as well as the cover, these will be good spares. If I burned the damned impeller up I will take some pictures of it and share them. I have no problem with others learning from my mistakes, it is why I make so many of them
Dave Graf
Re: Coulda, Woulda, Shouda
[Re: Coastie]
#17682 02/09/1807:37 AM02/09/1807:37 AM
Dave - it isn't necessarily limited to a pump problem. Any air leak on the suction will compromise the priming ability. Check all hoses, clamps and fittings.
Agreed, I checked every fitting connection and had just replaced all the hoses so they actually were the correct size for the fitting that they mated with (not the case before I started this part of the project). If they were responsible for the suction leak I would have expected the problem to continue after installing the new pump. The new pump primed and was moving water almost as soon as the starter engaged.
I think the dishwashing detergent being injected into the new pump had the effect of jump starting the thing. I will find some time today to tear down the old pump and look again for any other obvious problems. The new impeller I had installed when on pretty easily so it should have been able to center itself in the pump body. The old damaged impeller fought like crazy to come off the shaft and it is at least conceivable that there was damage done to the body in that old impeller failing. I knew full well how expensive the new pump was, so had gone to some lengths to avoid replacing it.
So my curiosity was killing me so I tore this pump apart for a much more careful inspection. First the flat inner wall surface of the pump is noticeably worn and has a ridge outboard of the shaft matching inner radius of the impeller. 2nd I really should have taken a magnifying glass to the shaft itself, it has multiple problems. There is a small diameter change in the shaft from the area that fits the impeller to the shaft itself. To my eye this is a machined feature, not one caused by wear, but would need to see the new shaft for comparison or the drawings. 3rd the impeller is still fine, but the shaft seal is burnt toast. The shaft was going to kill the new seal even if it had primed. If it had worked initially I think it would have failed again pretty quickly..
I don't have the tools to do a careful QA inspection, but my take on this is that the pump housing back wall wear and the shaft itself were both shot. Putting on new cover plates only solves the wear problem on the cover plate side. The inner side is wearing out too. I had been thinking it was the circumference that had become too worn. I think when I was buying my rebuild parts I looked into a new shaft and it was about $100 all by itself. It may be that replacing the shaft would have extended the pump life further, but this thing was well worn and has served its useful life.
The point of all this is that this simple little pump is not so simple.
I rebuilt a pump that had a scored bearing and shaft. I disassembled and inspected after installing a new pump. I purchased replacement parts (including the shaft and bearings along with the seals). To me it was worth spending about half the cost of a new pump to have it available in the cruising spares bag. It seems the only time I had pump problems was away from home when cruising, so it's a good insurance policy. Rhapsody's new owner has all that stuff now.
For sure several of these parts are going into the spares category including the new bearings and impeller and cover plate. That shaft though is not one of them, nor is the pump body itself. I will eventually buy a new shaft for a spare along with the cover gasket. I may take the pump body to the dealer for their opinion of its condition. They have been very informative and helpful so far. It would be nice to have the complete assembly ready the day you need it. I suspect that the new pump won't be needing more than new impellers for some years to come. If the old pump was original it really has had a long and successful life. I'm ok with a dealer making some money off me once in a while. It was also good to know you could actually get this same pump. I am also really happy this pump didn't croak when I was bringing the boat down the river. That would have gotten really expensive fast.
While I was in the Yanmar dealer's shop I did give a quick glance at what a new equivalent Yanmar replacement would cost. I was very happy to only be buying the expensive water pump after seeing that number and it will motivate me to get on with some of these other projects. Next winter I think I will follow your steps with the top end of the engine and transmission. I have no idea how many hours are on this engine, but it seems to be pretty strong and worth the effort to make it go a bunch more years.
I wasn't clear - I ended up with a total rebuilt pump as the spare using the parts I bought. I didn't carry the spare pump parts. It was ready to bolt in if there was another pump failure.