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cannot get water pump to work

P

pad1

Contributing Member
Dear Forum thanks to your help I have my Merc 700 working great, all new electrics. Starts and runs well. noted on the water yesterday that indicator stream was poor. when I flushed it after a day on the water, only air bubbles came out with a little water. I installed new impeller in already new water pump complete kit and housing only short time ago. Pulled pump off for second time, impeller correctly installed anti clockwise, drops into gear ok, tried pump in drum of water no go. back flushed motor top to bottom, water comes out bottom. Any ideas? cracked water channel perhaps. Feeling a bit dismayed. Motor bottomed hard on sand bar last day out my crazy daughter was driving, Is that likely to cause a problem? motor swung freely when ran aground, very little sand in cavity. many thanks key way correctly in place.
 
kimcrwbr1 said:
the driveshaft turns clockwise it sounds like the impeller is not right. Allways turn the driveshaft clockwise as your installing the impeller and then never turn it counter clockwise after the impeller is in.
http://www.ebay.com/itm/MERCURY-MER..._Accessories_Gear&hash=item23286cedaf&vxp=mtr
Do you have the water tube guide to line up the water tube in the pump make sure the water tube is straight and put some vaseline on the end of the tube so it pushes easy into the grommet on the water pump.
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I used a method off u tube replace the impeller, I'm pretty sure that I got it right. I'll check it again though for the third time. The water tube is already in the pump and pushes up into a housing right up in the leg. It has to be right or the gearbox won't install. I'm wondering if there Is a crack in the block. Thanks for the link I'll check it out.
 
Dear forum the pump is working fine, I pulled the gearbox off and sat it in a drum of water and turned the pump shaft with a drill, water pumped well. I back flushed wth the gearbox off and water came out the hole where the water tube goes in, that's the good news. The bad news is that I saw water spurting down inside of the leg at different place to where the tube goes in. is it likely to be a blown gasket between the power head and the leg? Or something else? many thanks...
 
Could be. I assume this is a Merc triple? (If not, ignore what I type below.)

You need to pull the power head off the adapter piece just below it and check the gasket. And while you're at it, remove the line (right side of the adapter) that goes to the fuel pump and plug it. That motor needs all the cooling it can get.


Jeff

PS: To prevent the adapter coming up with the power head--which pulls out the water tube and shifter--you want to leave in place the two rear nuts holding the adapter on. They do NOT go through to the power head, so they keep the adapter in place for you.
 
????---------Cooling water does come out of the block in different places.----What you see may be entirely normal.
 
racerone said:
????---------Cooling water does come out of the block in different places.----What you see may be entirely normal.
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Racerone, Do you know of ANy other reason that the water is not going through the block other than blown gasket or hole or crack in block?

cheers
 
fastjeff said:
Could be. I assume this is a Merc triple? (If not, ignore what I type below.)

You need to pull the power head off the adapter piece just below it and check the gasket. And while you're at it, remove the line (right side of the adapter) that goes to the fuel pump and plug it. That motor needs all the cooling it can get.


Jeff

PS: To prevent the adapter coming up with the power head--which pulls out the water tube and shifter--you want to leave in place the two rear nuts holding the adapter on. They do NOT go through to the power head, so they keep the adapter in place for you.
Click to expand...

Good tip, thanks, Never pulled a power head off before... do they put up much of a fight? oh yeah, and it's a triple

cheers
 
Dear Forum, well I pulled the power head off another old Merc 700 triple motor I had here and you were right racerone, the water was coming out of a return hole as it should. I checked everything again, flushed the motor right through from top to bottom and refitted gearbox carefully ensuring water tube went into right place and hey presto pump is working fine. It was a learning experience. NOw to the water, thanks for all your help

cheers
 
Good man. I hope you plugged that fuel pump cooling line, for that's critical to the survival of the top cylinder on these motors. Merc did the same on the last ones built.

Jeff
 
fastjeff said:
Good man. I hope you plugged that fuel pump cooling line, for that's critical to the survival of the top cylinder on these motors. Merc did the same on the last ones built.

Jeff
Click to expand...

The water line on my current motor passes through the fuel pump and into the side of the block. the tell tale water line passes out from the top of the block at the top piston in a different position; I figure this is an updated mod for this model Merc triple. I have another merc 700 triple exactly the same motor, but the water line does what you said and passes through the fuel pump and then the tell tale stream. and guess what, I burned the top piston in this motor; it's my next project, I'm going to put new pistons and rings

cheers mate
 
While you're at it, check the jetting. Merc went to a .074 jet in the lower carb and a .0785 jet in the upper carb to keep # 1 slug alive.

Jeff
 
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