Merc 110 water pump

Joined
Nov 7, 2004
Messages
21
I have a 1965 merc 110 thats in good shape.I lost water presure on it and
thought the water pump took a crap so, I went out and got a water pump.
Took the lower unit apart and got into the water pump (Not the first water or the last one i will do) When taking the water noticed the the drive shaft (that the water pump rides on) was worn and starting to surface rust (bad enough to where it was flaking) cleaned it up put the new water pump in and put it all back together. Put the lower unit back on the motor making sure to line everything up perfectly. Put the motor in a tank and fired it up. Well to my suprise there is still no water presure(not even a drip)Took everything apart again hooked the hose up to the copper water tube on the motor and made sure water was coming out of the motor and nothing was blocking it.That work great water flowed right throught with no problem. Now I go to the lower unit and hook a drill to the drive shaft (that goes in the motor) put the lower unit in the tank and hit the drill it seems to pump water out with no problem stick my finger over it and it has pretty good presure for a little Impeller. Now I think maybe I missed the water pump guide to the copper tube so, back at it this time for sure got it back together right. Same thing no water what so ever WTF. I have had the lower unit off the thing so many time tring different things tha i dream about putting it back together. If any one has any ideas or help what i should do I going bonkers here Please help before I take it to a shop..
 

d.boat

Chief Petty Officer
Joined
Sep 19, 2008
Messages
520
Re: Merc 110 water pump

I guess this is a stupid problem and know one can help

It could be that based on what you posted originally - that nobody can figure out what the problem could be other than a disconnect between the L/U water tube and the leg water tube.

You tested circulation between the water tube in the leg through the engine out the tell tale.

You tested the pump function by running the drive shaft with a drill.

The only other disconnect, at least from my limited experience is when you connect the L/U to the leg. The only thing I can think of is that the tubes aren't matching up but it sounds like you've checked and double checked that.
 
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