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merc 140 water pump/impeller

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dgsmooth

New member
howdy all - i have a 1994 merc 140 6 cylinder, and it doesn't pump water, been sitting for couple years. runs good for the few seconds i let it but no water coming out. i also found little black junks of hard rubber sticking out the water inlet slots/holes, so i assume the impeller is done.... is that a hard job? i'm not a marine expert, but i'm a heavy duty mechanic so i'm wondering if i could do that myself.... is the impeller down in the lower leg? i found a parts/breakdown diagram, and its looks to be down on lower leg, but then i'm wondering how it drives when motor in neutral and no drive down leg...... thanks to anybody with any advice....
 
Impeller is always turning. The gear box is in the leg and there is a rod that runs down the leg internally that spins c/w or anti c/w for forward or reverse. Your impellar sounbds like it is definately stuffed and you should not run engine again. You need to find serial number on the engine and post it here so people can tell you what type you have so you will be better informed. you will need that serial number to get the right part. Also if the impellar has disintegrated then you would have to assume some bits may have got into the block and could block thermostats or poppit valve. You would be best to remove all the stats and flush the system with a hose up the inlet port once the leg is off. Manual is the key here. You can do a fair bit wrong here and an exploded diagram isn;t going to show you all the possible pitfalls.
 
okay thanks mercmark, but if the gear box is in neutral and the rod isn't spinning, then whats driving the impeller? we ran it shortly with the water muffs on and nothing coming out, but we also didn't put it into gear.... but you're saying it should be pumping water all the time, even in neutral? the serial number of the engine is 7132530.... thanks for the help guys.....
 
oh yeah i need to find a manual, but i also need to have this done by next week..... maybe somebody with a manual will send me a couple pages of the info i might need.... thanks again to all.
 
To start with, somebody sold you the Brooklyn Bridge along with your 1994 motor.

The last Merc 140 was built in 1981. Your serial makes it a 1979 model built by Merc/Canada.

On outboards the driveshaft (which the impeller is connected around) is "always" spinning when the motor is running. The gears (start/stop) the "propshaft" from turning, or change it's direction of rotation. So if the motor is running, the waterpump is pumping.

Despite the age, Merc still stocks waterpump components for this model.

Grab yourself a Seloc's manual (in print or download form) for vintage of this motor and it will walk you through the process of servicing the waterpump.
 
That water pump impeller is very common from the early sixties and on .--------Used on all the big outboards and sterndrives for many , many years.---------Not sure about dealers that say " too old for us to stock those "------------they usually do not stay in business for very long.
 
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