Raw water pump impellor problems!

[J.J]

Hi, help needed! Has any one had simillar problems with the raw water pump impellor burning out!! it is on a 350 mpi sepentine belt, bronze housing its a 2004 motor. They only last about 20hrs and then fail!! I am well aware they can't run dry, and am extra careful having now having gone thru 3 impellors ! It might be a bad pump design on these? or getting air- locked? I want to replace the pump, on these pumps the impellor is a really deep and tight fitting type and the housing has a rib across the water in and out holes that wears a grove in it when it fails . I would like to find out what is the best raw water pump? surely they should be bullet proof!! Any advice would be helpful. Thanks.

 

[Bondo]

Re: Raw water pump impellor problems!

I would like to find out what is the best raw water pump? surely they should be bullet proof!!

Ayuh,... I've never seen a Bullet-proof impeller pump,...
They ALL use Rubber impellers...

I'd have to guess you're somehow runnin' yer's dry,...

 

[J.J]

Re: Raw water pump impellor problems!

Hi Ayuh, yea it must be getting air locked or something and running dry long enough to stuff it. Or it could be getting damaged slightly each time used untill it fails? Thats why im thinking this particular pump could be a bad design and the housing could be the problem. It might not be drawing the water from the leg quick enough... I flush it on muffs after use and make sure water comes out the exhaust bellows. Anyone else out there had repeated raw water pump failure? thanks, J.J

 

[thumpar]

Re: Raw water pump impellor problems!

Are you running it at all with no water? A couple seconds will toast it with no water.

 

[J.J]

Re: Raw water pump impellor problems!

No, I always make sure water is connected and hose running for a minute or two before start up and only ever let it idle on the muffs and only run it for a few minutes to flush out the salt water. I only start when boat is fully in water and off trailer. J.J

 

[thumpar]

Re: Raw water pump impellor problems!

When you say failing what signs are you seeing? Do you have a picture of one you have changed out?

 

[TilliamWe]

Re: Raw water pump impellor problems!

Nope, never heard of them failing after just 20 hours of normal use. Shoot, mine lasted 3 years and 400 hours! The black plastic pump housing has the same rib you speak of:

 

[J.J]

Re: Raw water pump impellor problems!

When you say failing what signs are you seeing? Do you have a picture of one you have changed out?

The impellor lasts a while then is burning off the the edges and leaves clumps of powderized rubber in the out lets like it is running dry when it looses suction or gets air locked, it has grooves worn in it on the outer edges and the middle where the ribs run. I will take some pictures and post them. On the housing the end plates do have some circular wear grooves on them but the walls seem ok.

 

[Bondo]

Re: Raw water pump impellor problems!

On the housing the end plates do have some circular wear grooves on them

Ayuh,... There's a Problem, right there...

 

[J.J]

Re: Raw water pump impellor problems!

Hi and thanks, took to engineer to machine end plate. He thinks that the impellor should probably have a plug on end to fill the shaft cavity .. anyone know about this ? it is the model with 2 flats on the shaft. It has never had a plug nor have the replacement impellors come with one?? J.J (tryed to upload photo but couldn't get it to work)