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Raw water pump maintenance

littlejrs

New member
I have a SeaRay 240 SD w/ 5.0L MPI Bravo III engine. I was told I needed to replace my raw water pump (not just the impeller) b/c there are grooves in it. I have been doing some research and have a few questions.

1) The service manual states the housing cover can be resurfaced to remove grooves. I don't see anyone posting about this. Is this a viable option? If so, where should I take it to be resurfaced?

2) The manual also states there is a replacement housing cover made of composite material w/ replaceable stainless wear plate. I can't find this online. Is it better to have a wear plate to replace rather than replacing the whole housing? If so, do I have to switch to the composite housing and where would I find it?

Here is the model of the raw water pump I currently have:
MER46-862914T10

Thanks!!!
Jill
 
If there are grooves in the housing, it is usually much cheaper to buy the whole pump than pay for a new housing and then the labor to "switch the guts". Look at the link guy provided and do the math....

If it is just the endplate, and the grooves aren't too deep, you can do it with a piece of plate glass and some wet paper. BTW, the wear plate only "protects" the cover plate, won't do a thing for the housing's sealing surfaces.
 
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Jim, I'll toss in my two cents here if you don't mind.

I'm not a Merc guy, but I do understand sea water pumps, and most operate very similarly to one another.


First, your style pump does not use a cam, so if you read anything that suggests to replace the cam, pay no attention to this.
Your style pump places the impeller shaft eccentrically within the pump body to create the same action as does a pump with a cam.
Difference being that the eccentrically positioned impeller causes the same three/four vanes to be folded over to create the suction/pressure as does a cam with an impeller shaft that is center positioned.

Here's an impeller pump that uses a cam to fold the vanes over.
The shaft is dead center within the pump.
Water_Pump_Impeller.jpg



This is not your Merc pump... examply only, but will be very similar in function!
If you look closely, you'll see that there is no cam and that the impeller is eccentrically positioned off to one side.
In some respects, this style doesn't wear the impeller from cam friction.

images





All sea water pumps have two thrust surfaces and are where we'll see the grooving.
More so at the side where the intake/pressure ports are, since it's more likely that debris will be brought in at this side.

Ditto the resurfacing of the thrust surface. Most can be saved if the grooves are not too deep.


As an added note, impellers that are used more frequently tend to outlast impellers that undergo winter lay up for long durations.
When an impeller sits at rest within the pump body, these same three/four vanes that are folded over against the cam or eccentric (such as in your case) tend to cause the material to take a "set".
Here is an impeller that is damaged simply by Father Time.
The material has lost it's resiliency, and if you look at the 6:00 O'clock area, you'll see the set.
images


This "set" is more harmful to an impeller than continued usage is.

Point being: If you lay this engine up for winter, it's more likely that you'll want to change the impeller more frequently, IMO.


I use the crankshaft pumps on my engines. These are very easy to access the impellers by simply removing a cover plate.
I pull the impellers each winter and store them.
This saves them from the "set" that would otherwise occur had I left them installed for the duration.

With your belt driven pump, this is not as easy.
However, if you are removing the pump to inspect the impeller upon re-commissioning, you might want to consider doing this at lay up time, and just leaving the impeller out.

I believe that Merc makes a recommendation for a two year service interval.
I can't bring myself to leave an impeller installed for the winter lay up without at least looking at it come spring time.


Your call on that!
 
Lay 200 grit paper on a flat board or sheet of heavy glass and work the face over the paper. Change to 400 grit after a bit of sanding and finish w/800 to 1000 grit until smooth.
 
I don't see an option to buy either the brass pump or the composite w/stainless plate. Are all new saltwater pumps the new composite w/stainless plate? My manual states the composite is an alternative to the brass. Maybe the part # is just different?!?!?!!??
 
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