Merc inline 115 will not pump water

[Bob37814]

I have posted many times before with great success, Hopefully someone can help me out yet again. My motor is a 1975 Merc 115 s/n 4114055. Runs absolutely great, but does NOT pump water at all....I changed and put in a new impeller, wear plate, and gaskets. before I did all this work, I put 125psi of compressed air in the main water tube that goes into the pump housing and I could feel it coming out the pee hole. There wasnt really any resistance. I am running this motor in a plastic tote filled with water to the top of the water intakes. I am wondering if I would be better using flushette muffs on this engine as opposed to running it in a tote full of water...Please help. emckelvy? chris1956......clams?

 

[emckelvy]

Re: Merc inline 115 will not pump water

If you're talking about the main intakes below the anti-ventilation plate (where an "ear-muff" flusher would go), that isn't even far enough to submerge the pump in water so it'll self-prime. If you need to run the motor in a 'bucket' you're better off having one large enough and deep enough to submerge the motor at least up past the lower motor mounts, and preferably to the mid-level of the exhaust tower.

Failing that, better off to run on a flusher. Turn the water pressure up so that a little water spills out of the muffs. Once you start the motor, it'll suck that water up and you'll need to apply more pressure. Only turn the hose up enough to start spilling water out of the muffs. Doing this ensures the suction side of the pump is fully flooded.

If you find it's still not pumping for you, better pull 'er back down and inspect the impeller for damage. Hopefully it won't be hurt and had enough pre-lube or got a few splashes of water up in the pump to lube the impeller blades.

HTH & let us know what happens............ed

 

[Bob37814]

Re: Merc inline 115 will not pump water

Well Ed, That helps me figure out 2 things actually, No. 1, thats probably the main reason my first tower of power melted the no.1 piston......valuable, costly lesson just learned...No.2, That explains why it was getting so hot in the first place. If it killed my new impeller and I have to replace it again, I'm a wiser man for it, if it didnt burn the new one up....I'm a lucky one. looks like I'm gonna get a pair of muffs afterall...I didnt think that blasted tote was deep enough in the first place, shoulda went with gut feeling....Will post results later. Thanks again Ed. - Bob

 

[Bob37814]

Re: Merc inline 115 will not pump water

Well.....Tried the earmuffs, no dice man. Dropped lower unit and gutted water pump yet again...Found it busted to shreds....Got new impeller today, no time to install as I work outside and darkness has arrived yet again. Guy at marine repair shop said to check grommet inside impeller housing where main water tube connects, of course I bought one just in case, came home to find existing grommet split down the side. Noticed copper tube itsself was buggered up, which caused the big nasty slice in the old grommet....Good thing I have spare exhaust leg from previous 1150 merc....Question, Is there somekinda spacer that slides down the driveshaft and sits on top of the water pump housing???? If I remember correctly on my other 1150, there was. Whats its purpose???? Will the absence of this (spacer) cause it to lose enough pressure to not pump water????? I was told that the housing grommet being bad may had a lot to do with it not pumping.....Bob

 

[jimg984]

Re: Merc inline 115 will not pump water

the spacer maybe a water slinger for any water that gets by the seal.
the empeller being shot if it was new,, may be cause by the fingers where turn in the wrong direction on installtion. shaft must be turned in normal run postion with finger pointing back... if not they will try to turn back when its cranked and running

 

[emckelvy]

Re: Merc inline 115 will not pump water

The rubber 'spacer' that slips down the driveshaft to rest at the top of the pump body is a "slinger ring" that keeps sand/debris/etc from grinding away at the pump/driveshaft area (hence the "slinger" connotation. Its presence or absence has no effect on pumping action.

If the end of the water tube isn't too buggered-up you can restore it to roundness if you're careful. Spread a thin coating of waterproof boat bearing grease (or equivalent) on the rubber grommet and also the end of the water tube.

Note that you should also have a plastic "guide tube" that slips into the pump, over the top of the rubber water tube grommet. If you don't have that guide sleeve it'll make it real hard to get the copper water tube into the pump as you're installing the lower unit. Might be the reason for the tube being messed up in the first place.

And lastly, while it's certainly better to turn the impeller in the correct direction of rotation when installing it, the impeller blades are plenty flexible enough to 'right' themselves once the motor is running.

HTH..........ed