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Raw water Pump not pumping

E

eldstuff

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I'm having trouble getting my rebuilt sherwood pump to work on my 318. The old one was siezed up after 2 months of setting so I replaced it. Now I get nothing although the belts are taut and pump is turning. I noticed that the pump is above the water level and might have some air on the inlet side when I replace the hose. Could I have an airlock? I've replaced the pump on the other engine and there was no problem. If I do have an airlock, how do I clear it?
 
capnlazy said:
Also be sure you have the inlet and outlet hoses on the correct side (pulling water instead of pushing it).
Click to expand...
Yes, seacock was/is open. Hoses are in the same position as when I pulled the blown pump. Keys are in place and the impeller vanes are bent in the right position for the direction of rotation. This is a single impeller pump so it shouldn't be all that complex. I'm thinking of hooking up a water hose and forcing water out, on the exhaust side then the intake side, with the thought that one of the hoses has collapsed. Does this compute?
 
FWC or RWC? I've had this problem with some 318s (RWC) at the start of the season when the block is empty. Have found that by filling the block (on RWC) and hoses has always solved the problem. It's like priming the system.
 
Before you pull hoses, prime, etc, tell us which style belt driven Sherwood Pumps you have!
And tell us which engine this pump is fitted to... (the Standard LH Rotation, or the Reverse RH Rotation engine)?

There are several styles of this belt driven pump, some of which are very easy to install 180* out of correct indexing.... and in particular when we have LH and RH engines.

These belt driven pumps, for example:
3504582637094040_1.jpg
72508_THUMBNAIL.jpg
350455984799_0.jpg


If any of the above pumps are out of phase by 180* (as per engine rotation), they will not pump water.

This pump in this orientation would be for a Standard LH engine (CW if viewed from the front of this pump).
Note how the impeller blades would open as they leave the pump cam, (creating suction) .... then folding at the cam again (creating pressure).
(all in a clockwise direction for a LH engine when viewing from the front of the pump)
attachment.php


This same pump in this orientation would be for a Reverse RH Rotation engine (CCW if viewed from the front of this pump).
Again, note how the blades would open leaving the pump cam.... folding again upon contacting the cam...
(all in a counter clockwise direction for a RH engine when viewing from the front of the pump)
attachment.php



The important thing to note, is that:
Suction is created as the impeller blades "leave" the cam and open back up.... causing the area between blades to become larger.
Pressure is created as the impeller blades "fold upon" the cam... causing the area between blades to become smaller.

I don't know which pump you have...., but this may be as simple as flipping the pump over 180*.



.
 

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Thank you for your suggestions WoodieMan and RicardomARINE you have given me something to think about. I'm going over to my boat tomorrow and I have some experimenting to do. I will let you know how I make out next week when I get back home. I really appreciate the help.
 
Study the below diagram to determine what you should have. (The drawing depicts both standard and reverse rotation engine set ups.) The pump body goes two ways, but only one is correct.

Jeff
 

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Eldstuff, since the one pump did not pull in water in.... and I assume that you tried several times......, and if it spun for any substantial amount of time, you may have burned it.
I'd strongly suggest that you remove the impeller and examine it before assuming that all is OK.
Hard to say..., but not worth risking, IMO.

******************************

Good call, Jeff.
Your two images explain this a tad bit better.

attachment.php


Image above = the pump below ....................................... Image above = pump below
for Reverse RH Rotation engine .......................................... for Standard LH Rotation engine.

attachment.php
...........................................................................
attachment.php


NOTE: Keep in mind that LH and RH engine determination is as though viewed from the Flywheel End... not the Front end of the engine.
I've used "CCW" and "CW" to describe the pump rotation........ not the technically correct engine rotation.



Question for Jeff:
Your notation for "Port" and "Starboard" would appear to be reversed if used for straight drive I/B's.
Does the image below look more correct?
 

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always have to prime mine, plus when I install the impellers I use dish soap, helps with the first few seconds of running, has saved an impeller or 2
 
Once you get the pump body turned the right way,take the outlet hose off fill it with water and she should be primed up put the hose back on and let er rip

Bubbled paint on the back of the housing means you smoked the impeller!!! Better check it !!
 
OK guys, I just got back from my boat which is moored in the San Juan Islands in NW Wa. With your help I finally got my RW pumping. I tried priming. I checked and rechecked impeller. Finally turned the pump over as suggested. On this engine (starboard) this was not an easy thing to do with hoses and belts all in the way. Skinned my knuckles several times. Started the engine and sure enough the water gushed forth. I eventually, probably would have done that (maybe) as a a last resort. Thanks to all of you for your excellent advice.
 
Ditto Jeff's comment.
It can take only seconds to burn an impeller when dry.
And since you gave this several attempts, I'd be checking it.

This will be cheap insurance that all is good. :D

.
 
You bet! I was at the boat ramp today when some MORON pre-fired up a V-6 OB (a Yammie I think) on the trailer while waiting to launch. He blitzed the throttle several times, then let it fast idle for at least 10 seconds before blipping it again.

I didn't get to see what happened when he launched--had to go--but I can guess!

Jeff
 
Jeff, I see this all too often.
If ya walk over and make the suggestion that they just fried their impeller........ suddenly you're the "A" hole who should mind his own business!
If ya don't say anything, then they're likely in for trouble and a ruined day on the water.

I've been both the "A" hole and the helpful "save-the-day" guy before.
Six to one... half a dozen to the other! Dammed if you do.... Dammed if you don't!

.
 
Thanks again for your input. When I removed pump to reverse ends I did check the impeller and it looked Ok. Since the old impeller was still good, I now have a spare for emergencies. Thanks
 
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