Water pump won't prime!

[wotan2525]

I'm really at my wits end here. Boat is overheating and not pumping any (or not much) water. Here's what I've done:

Removed water pump and impeller, sealed everything well with RTV to make sure that their were no air leaks. Visually inspected the impeller -- no knicks, no broken fins.

Flushed both hoses that connect to the water pump. One of them had quite a bit of old impeller parts in it. Was sure that this was the issue but has not made a difference.

Removed thermostat and flushed thermostat housing.

Boat runs fine on a hose.... I'm assuming because this creates positive pressure on the supply side. Here's the tricky part -- when I run the supply into a bucket that is hose fed, it will create TONS of suction. But ONLY if the system has been primed with the hose before that. If I disconnect the supply and allow air to get into the system, the water pump will not develop any kind of suction.

With the garden hose connected there doesn't appear to be any leaks in any of the hoses. Hard to inspect the one that runs under the engine, but it seems fine?

I've had to be towed in 3-times this season because of this!

[CornRickey]

Sounds like your sucting air from somewhere. Once the pump is primed (by the hose) the pump draft is able to overcome the air leak. But its self priming ability isn't.

[ngavchris]

I had the same problem a couple of years ago. Talked to skidim...... I had already tried a new impeller. Replaced the entire raw water pump and haven't had an issue since. The old one looked fine, but skidim said that they wear out and loose the capability to create suction.

[cadunkle]

Typically the thrust/sealing surfaces on the front plate nad in the back of the impeller cavity will wear, so the impeller won't seal well. Once there's water in there it closes up the gap. On old style pumps with metal impellers they had grease zerks and you're give it a couple pumps before starting so the pump would prime.

[wotan2525]

Typically the thrust/sealing surfaces on the front plate nad in the back of the impeller cavity will wear, so the impeller won't seal well. Once there's water in there it closes up the gap. On old style pumps with metal impellers they had grease zerks and you're give it a couple pumps before starting so the pump would prime.

There's got to be a rebuild option available. A new sherwood raw-water pump is $500. Tough pill to swallow!

[92SupraComp]

skidim has all the parts needed to rebuild the pumps. they well priced except for the sealed bearings. $25 a pop!!! you can pick them up for way cheaper. but everything else is well priced

[wotan2525]

skidim has all the parts needed to rebuild the pumps. they well priced except for the sealed bearings. $25 a pop!!! you can pick them up for way cheaper. but everything else is well priced

Sounds like you've done this? Any info on how I can figure out what I need? There is no extra play or slop in the bearings that I can feel. The overall condition of the pump is pretty good. I'll try to pull it back out and take some photos maybe....

[wotan2525]

Found information about rebuilding. http://www.pumpagents.com/pdf/SherwoodPumps/G55-2.pdf

My pump does not (nor has it since I've owned it) had the "spacer plate." This is part #7 on the exploded view. Can anyone confirm that their pump has this?

[sybrmike]

Yes, mine has the thrust plate (#7). I didn't know I had one either, but it came apart while disassembling the pump for general clean up and impeller replacement. I only had the impeller and o-ring from skidim on hand, so had to cut my own gasket ( #8 ) to finish putting it all back together.

[92SupraComp]

Found information about rebuilding. http://www.pumpagents.com/pdf/SherwoodPumps/G55-2.pdf

My pump does not (nor has it since I've owned it) had the "spacer plate." This is part #7 on the exploded view. Can anyone confirm that their pump has this?

this is probably why it wont work. YOU NEED THAT PLATE. period. no questions. Its absolutely necessary to have that. Yes all the pumps need that plate. It seals against the impeller. Its a wonder that it creates any suction once its primed. I dont know how on earth you pump it working with that piece missing. It should fix all of your problems once you get one and put it in.