New water pump back plate quick-change kit

[Don Moyer]

I don't recall any new product creating more of a buzz among our staff than that generated by the MMI water pump back plate quick-change kit that we just posted to our online catalog.

Spurred on by the thumb screw and o-ring design used on our new MMI flexible impeller pump, we couldn't seem to turn off the informal think-tank out behind the shed, and before we knew it, we had added a captive feature to the thumb screws, so they wouldn't drop into the bilge if (when?) dropped.

A wonderful byproduct of the captive feature is that the tip of each thumb screw is held out ahead of the back plate as it's being installed. In this way, the tips of the screws tend to find the screw holes in the housing of the pump, thereby helping to orient the plate in the correct location over the impeller chamber.

These features are, of course, particularly useful during on-boat maintenance, where access is usually very limited.

The kits will fit on all MMI flexible impeller and Oberdorfer Model 201M and 202M series pumps.

Here is some additional information on the kit.

[radiance91]

I love the captive screws..the best idea in the world!. my water pump is hard enough to reach on my P30..
I do have one question...Water is dripping from the back plate. I havent been able to fix the problem yet..
.A friend and I are debating if there's a gasket to go along with my Oberdorfer pump ..He says yes I say no..I thought there's just an O RIng..
Can you be so kind as to clarify this debate! thanks

[CalebD]

The Oberdorfer water pump back plate does require a gasket. It is a thin gasket but a gasket none the less.
MMI sells them.

[radiance91]

thank you!

[Kelly]

Actually, the captive screw water pump back plate is delivered with O-rings, thereby eliminating the need for a separate gasket. The installation instructions suggest putting some grease on the O-ring before installation. Here's the text:

1) Remove the original back plate and clean the rear surface of the pump housing.
2) Turn the thumbscrews into the back plate, until the unthreaded part (just below the head of the thumb screw) clears
the threads in the outside face of the back plate. In this configuration, the tips of each thumb screw will protrude approximately
1/6" beyond the forward face of the back plate to help find the retaining screw holes in the housing (fig. 1).
3) Inspect the o-ring, to be sure that it is securely seated within its groove in the back plate, and apply a small amount
of general purpose grease over the o-ring (fig.2)
4) Carefully orient the back plate over the back of the pump until the thumb screws line up with the holes, and sequentially
tighten all the thumb screws (fig. 3)

[radiance91]

Thank you We did all of the above..thank you for the information. It still leaks..must be some other issue..Still investigating..

[CalebD]

Kelly is correct and I was wrong about using a gasket with the captive screw water pump back plate. It is supposed to rely on the 'O' ring for a seal.
You might need a new 'O' ring - see cooling parts in online catalog.
Are the mating surfaces clean and smooth?

[ArtJ]

Be sure the surface is cleaned and unmarred. Also you need to use some
lithium grease to both hold the o ring in place and provide initial seal.
Doing this, you will find it seals quite nicely. I also tightened mine with
a pliers because they tend to back off otherwise, even with lock washers.

Regards

Art