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  #1   IP: 71.16.159.194
Old 11-10-2008, 09:57 AM
Jesse Delanoy Jesse Delanoy is offline
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Leaking water pump

After taking some hull damage, our boat was hauled out for the winter in late August. From that time until this past weekend, the engine has not been started (late model A4, Moyer rebuilt with a Moyer water pump). Shortly after the haulout, I did a pressure flush on the engine, in preparation for winter layup.

Hull repairs and painting having been completed, I went this weekend to winterize the engine. Upon pulling the thermostat, it appeared that there was no water whatsoever in the engine - at least the thermostat well was bone dry. This didn't surprise me, as I expected most or all of the water had drained out of the drain holes in the course of the pressure flush.

I started the engine up, and ran it a bit to warm the oil, in preparation for an end-of-season oil change, before adding antifreeze and fogging with MMO. I noticed water leaking out of the bottom of the water pump. On closer inspection, it appears (though I can't be sure - visibility is limited) that the water is dripping out of the back plate of the water pump. There still seemed to be plenty of water running through the engine and out the exhaust port on the stern, but I'd call the water leaking from the pump a fast drip, at idle. I'm sure it would be heavier with the engine in gear and at cruising speed.

My plan is to pull the pump before next spring, install a new impeller (which is probably due anyway - got about 250 hours on the old one) and re-seal the back plate. My understanding is that this pump uses an o-ring, not a flat gasket, on the back plate.

My question is, what would have prompted this pump to begin leaking under these conditions. Have not had any trouble with it over two seasons of fairly hard use. Could the o-ring deteriorate just from sitting there dry for a month and a half? Any other thoughts?

As always, thanks for the help.

Jesse Delanoy
s/v f/k/a Agape
Baltimore
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  #2   IP: 38.118.55.136
Old 11-10-2008, 01:32 PM
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Don Moyer Don Moyer is offline
 
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Jesse,

The o-ring in our quick change back plates should definitely not deteriorate in 250 hours, and I wouldn't really expect them to deteriorate at all. I assume you tried to tighten the thumb screws a bit? I'll be in our shop tomorrow morning, so I'll pick up a spare o-ring and send it to you.

When you remove the pump to replace the impeller, you can inspect the rear surface of the housing where the o-ring seats for any minor blemishes. When we use the quick change kit on older Oberdorfer pumps, it's frequently necessary to use a standard back plate gasket to create a good seal due to imperfections in the pump housing. Use of a gasket doesn't really detract significantly from the quick change feature of the kit.

Don
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  #3   IP: 71.55.92.249
Old 06-30-2009, 10:57 AM
shulerb shulerb is offline
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Another Water Pump Query

I've got two water pumps and looking to rebuild them both (keeping one as a spare. I plan to purchase the upgrade parts. They both appear to be in excellent condition (despite their age). The problem I seem to be having is a leaking pump. I pulled out the impeller shaft in both pumps and realize they both have a slight groove toward the center. One is worse than the other. Could this cause leaking of the pump?
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  #4   IP: 66.126.90.242
Old 06-30-2009, 12:26 PM
Kurt Kurt is offline
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Since I have had lots of water pump woes and rebuild experience, I'll chime in here. A leaky water pump is caused by a failed seal (oil, water or both). A scored shaft can cause your seals to fail prematurely, but I'm not sure that a scored shaft in and of itself would directly cause a leak, just contribute to a seal's failure or cause it to have difficulty creating a good seal due to the shaft wobbling, etc.

Moral of the story is replace all the guts - seals, shaft.
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  #5   IP: 71.55.92.249
Old 07-06-2009, 01:54 PM
shulerb shulerb is offline
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That's what I had planned to do and I appreciate the input Kurt.

Thanks,

Shu
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  #6   IP: 74.101.134.42
Old 08-13-2009, 10:07 AM
fixxxer0 fixxxer0 is offline
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when you replace the backplate is it required to put grease on the o-ring again? (i remember a little bit of blue grease coming with it originally)
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  #7   IP: 65.89.243.247
Old 08-13-2009, 11:50 AM
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roadnsky roadnsky is offline
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It's not REQUIRED but it is RECOMMENDED.
If nothing else, it helps to "lock" the O-Ring into the groove when you put the back plate on.
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  #8   IP: 74.101.134.42
Old 08-13-2009, 01:01 PM
fixxxer0 fixxxer0 is offline
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hrmm.


my pump was working perfectly, no leaks or anything, with just hand tight.

but then the engine over heated so i took off the plate to make sure the impeller wasnt messed up and when i put the plate back on it leaks a fair amount now.

i tightened those thumb screws as tight as i could by hand without making my fingers bleed and it still leaks.


maybe ill take it off and put grease on it, i dunno...
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  #9   IP: 65.89.243.247
Old 08-13-2009, 02:53 PM
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Quote:
Originally Posted by fixxxer0 View Post
hrmm.


my pump was working perfectly, no leaks or anything, with just hand tight.
but then the engine over heated so i took off the plate to make sure the impeller wasnt messed up and when i put the plate back on it leaks a fair amount now.
i tightened those thumb screws as tight as i could by hand without making my fingers bleed and it still leaks.
maybe ill take it off and put grease on it, i dunno...


IF the O-Ring didn't stay in the groove when you put the plate on, then it WILL leak no matter how tight you turn the finger screws.
I'd suggest taking the plate off carefully to see if the ring might have been damaged...
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