![\"IMG_3130-sm\"](\"http:\/\/www.decamp.org\/wp-content\/uploads\/2013\/05\/IMG_3130-sm.jpg\")
<\/a><\/p>\nThe picture above is of the Sherwood G-908 pump specified by the factory. My first issue is that the body of the pump is made of a material that rusts. \u00a0I understand that the body of the pump is not supposed to come into contact with the seawater (the pump chamber proper is bronze), except that it does. If the seals start to leak (as occurred with this pump) sea water comes out the weep holes, by design.\u00a0 And the pump is installed in a marine engine room, a harsh environment.<\/p>\n
The second issue I have is that, to inspect or change the impeller, you have to remove three bolts that are on the back side of the pump body. It’s very, very difficult to get a wrench on the bolts with the placement of the pump.<\/p>\n
Just a bad design. But unfortunately, this is the only pump made to fit this engine. In the picture below, you see some of the challenge. The mount plate is small and diamond shaped, and there is little clearance.\u00a0 In the picture above, the keyed shaft at the top of the pump fits into the slot in the picture below.<\/p>\n
Oberdorfer makes a pump that doesn’t have these design issues and has an appropriate pump volume and compatible shaft. It’s also $100 less expensive than the Sherwood and merely ridiculously expensive.\u00a0 But it has a different shaped base that won’t fit the M-35B (see picture below). \u00a0The good news is that was easy to fix.<\/p>\n First step was\u00a0to make a template of the mounting plate by taking a rubbing and then transferred that pattern\u00a0to the base of the pump.<\/p>\n Then I broke out the power tools. \u00a0I used a rotary tool (basically, a more powerful Dremel) with a cut-off wheel, which went though the bronze like butter, then cleaned up the edges with a grinder and a mill file. \u00a0I used a hand-held drill (the tolerances are not tight) to enlarge one of the bolt holes. \u00a0Total time was about 30 minutes. \u00a0 A few minutes more with some bulk gasket material and scissors and I had a stack of custom gaskets.<\/p>\n As an aside for those who know me well, you may have noticed in the picture above that the top-right side of the pump base is still a little larger than the gasket.\u00a0 This side of the pump base did not need to be altered to fit the engine.\u00a0 After considerable thought (there may have been twitching), I decided not to give into the OCD and that good enough was preferable to perfect.<\/p>\n One other modification was needed. Because the pump fittings are a little closer together on this pump compared to the the Sherwood, I had to grind one of the hose fittings so that it would clear the other one while screwing it in.<\/p>\n \u00a0 The modified pump was easy to install and generated an equivalent flow of water. \u00a0A sea trial verified that the engine temperature is stable under load.<\/p>\n (March 2014 checkpoint: \u00a0the pump continues to operate as intended.)<\/p>\n <\/p>\n As a final step, I was going to rebuild the seals on the old Sherwood G908 pump so that I would have a spare pump.\u00a0 Judging by the picture below, I waited too long!\u00a0 I’ve removed the seals, but the bearings have fused into a lump of rust and the shaft is scored and pitted.\u00a0 A slight weeping was noted in the original marine survey, so it’s likely that the bearings were toast even then.<\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/a><\/p>\n