sherwood raw water pump

[Hawk]

Thanks guys. Maybe its a wear plate I'm looking for as it wasn't evident to me when I changed the impeller yesterday. Could it be missing? If so, I ought to have seen leaking I expect.

I'm going back now to take it apart. Thanks for any more feedback fellas.

Hawk

[Craig Illman]

This shows a parts breakdown: http://www.marinedieseldirect.com/catalogs/catalog_group.php?owner=mdd&page_ident=200142-58&model=M-25%20/%20M-25XP%20/%20M-25XPA&manufacturer=Universal&title=Sherwood%20Water%20Pump%20-%20New%20-%20302648&quant_position=&catalog=200142&printparts=200142&printservice=200151&printoperators=200157&comment1=This%20pump%20is%20no%20longer%20available%20as%20a%20complete%20stand%20alone%20pump%20unit%20(302648%20-%20NLA).%20%20Use%20this%20diagram%20to%20order%20replacement%20parts%20for%20this%20pump.%20%20To%20replace%20this%20pump,%20order%20kit%20number%20302837(kit%20includes%20a%20replacement%20pump).

Craig

[Hawk]

Thanks Craig. Thats helpful.

[Ron Hill]

Guys : There is NO paper gasket between the face plate and the impeller housing on a Sherwood raw water pump - there is on an Oberdoffer.  There is a "thick paper? gasket" between the Sherwood pump and the engine.
What seals the face plate on the pump housing (impeller inside) is an "O" ring.

On the newer Sherwood #908 pumps is that the "O" ring seals the pump (bronze) housing to the pump body(iron w/bronze plate in between!!) by 3 bolts. Those design engineers had their head up their "you know what" because the 3 bolts are threaded to the pump housing from the inside. 
One step forward and 10 steps back!!  A thought 

[Hawk]

I took the Sherwood pump apart again and relying on Craig's parts breakdown drawing it does appear that a gasket fits between the wear plate and the pump body. Of course the 3 gasket holes fit the bolt positions but I did not see any reason to change dthe gasket. So I removed my mis-positioned gasket. and all is well.

It all started when I sucked something up the raw water intake as I left the outstation and noticed quickly a reduced water discharge. After limping back to dock, I removed the hose from the water strainer and cleared the obstruction with my trusty coat hanger. I thought it might be prudent to change the impeller as it likely ran a little dry.

Just for information, yesterday I motored for 1.5 hours at 2400 rpm and the temp gauge was steady at 170 degrees. I have an M35 with 3 blade prop.

I appreciate all the good advice fellas.

Hawk

[Jack Hutteball]

You guys are all lucky enough to have your pumps last long enough to need to change the impellers.  The impellers have all been perfect on the last three that I have replaced with bad seals. I am getting good at switching pumps though, can do it faster than changing the impeller.

[Hawk]

By the way I should have said that the sherwood impeller I removed looked just fine even though it likely ran dryish for 10 minutes...it went to the emergency spare box.

[Ron Hill]

Jack : You need to get a Globe "blue rubber" impeller.  Then what I do is reverse it the next year so the blades don't retain a "set".

Hawk : If your impeller you took out is "black rubber" I'd recommend that you spray it with silicone.  Then put it in a zip lock bag so it won't dry out and become brittle!! 

[Hawk]

Ron,

Great point. I had read that previously but forgot to do it on the weekend.

[Jack Hutteball]

Ron, my spare impeller that I have yet to use is a blue Globe.  Maybe the seals on this pump will last long enough to use it!  One interesting thing when I changed out the pump this time I also cleaned out the raw water intake strainer (which I check on a regular basis) I completely drained all the water out of the strainer housing.  I found a layer of "silt" in the bottom of the housing that I had not noticed before.  It may be possible that the water in our area contains a lot of silt that is playing havoc with my pump seals.  We do have several glacier fed rivers nearby, just maybe ...