My raw water pump just failed after 17 years of faithful service. I learned a lot while getting it taken care of and thought I'd share it with the board, since it could be that you're all driving around ageing pumps. I've got the Universal 3 cylinder model 25 engine, but the info is probably good for any Universal owner.
The first sign of trouble is that the starboard forward motor mount starts showing water spots and corrosion worst than the port side. This means sea water is leaking past your seals and running down the shaft. I thought at first the cover plate gasket was just leaking and replaced only that because the impellar (still original) looked fine. I've got the Oberdorfer bronze pump which is guess is a replacement for the Sherwood that some boats have. Apparently they had problems with the Sherwoods and converted over somewhere along the line. The CD parts catalog shows both.
The shaft that turns the impeller is free floating and as the years go by and the impeller wears the shaft rides forward and scores the back or inside of the cover plate. When you install a new impeller you have to smooth off the back of the cover plate to maintain a good seal. You do this by putting a piece of emery cloth or heavy sandpaper on a flat surface like a pane of glass and sandiging back and forth being careful not to tilt the cover until the scoring disappears. Since Westerbeke bought out Universal they've jacked the parts prices way up to compete with Volvo prices. The paper gasket which is much thinner than a shopping bag now costs $4. No reason to pay that, make your own out of a shopping bag, manila folder or what have you and coat both sides of the gasket with RTV gasket cement. Two different mechanics told me that's what they do even when you're paying for the gasket. Finger tighten and let the gasket cement go off over night before cranking down on the screws. As long as you're in there replace the impeller as well. It's been in there a long time even if it looks OK and you can put it in your spares box for an emergency. You coat it good with liquid detergent before you put the new impeller in otherwise it may grab the walls and tear it's new self up. Well and good, but this didn't solve my leak. It turns out the seals are almost always shot too so you might as well buy the whole kit with impeller, two seals and a gasket for $40 if you're going to tackle this job. To replace the seals you have to remove the pump from the engine and remember to close the seacock first unless you're hauled out. The seals go in facing in opposite directions so look carefully before you take the old ones out. One holds the oil in the engine back and the other holds the water in the pump inside. The outside seal prys right out with a screwdriver but the inside one is a challenge. There's no lip to get under and it's at the bottom of a two inch deep shaft. You usually wind up mangling it to get it out. This is the hardest part of the job. Check the shaft carefully for scoring. When the seals go bad the metal rubs on the shaft and scores it, then the new seals won't seal because they need a smooth surface to make the seal. My shaft was history and I ordered a new one at $ 70+. We probably should be replacing the seals every so many years so that they don't wear down enough to score the shaft, but who except Larry Pardee is organized enough to do that? Make yourself a gasket to go between the engine and the pump using the same technique as the cover plate gasket and you're in business. Here's a trick to file away: The mechanic told me that you can sometimes get around replacing a scored shaft by not seating the new seal all the way down. That way it rides on a new spot on the shaft that hopefully isn't scored and can get you in where you can get a new shaft.
Incidentally I carry a spare raw water pump with me that I bought ten years ago for $80. They are now $240. I tried to just bolt it on, but it wouldn't go. Although I bought it from an authorized Univesal/Oberdorfer dealer and the part number was correct, it turns out that some Oberdorfer pumps have an eighth inch high ring on the back rather than a smooth surface. That version will not bolt on and I had to take it to a machine shop and have it fly cut off so I'll be able to use it next time. Oh, and by the way, if you have a spare pump you shouldn't leave the impeller inside the pump for a long time in storage. One or two of the impeller fins are bent over if left inside this weakens them. Take the impeller out and store it outside the pump.
My old pump had a grease cup which I turned religiously for all these years. The new pump does not have one nor a zirk fitting. The mechanic says that they have made the seals and bearings out of different material in the new pump that doesn't need greasing. That may be, but it may be a way to tell if your spare pump is identical to the old one and whether you should be suspicious about it having a ring that makes it unusable.
Just something to worry about all winter -- or maybe you want to take your raw water pump apart and check the shaft and replace the seals. What else do you have to do? Out here in Calif we're still sailing. Say, if you go South for the winter you're a snowbird, but if you don't go South are you a "snownerd"? Happy Holiday to all on the board and I hope this helps somebody.
TomCambria@mindspring.com
Raw water pump information
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