1979 merc 115hp water pump replacment?

[Georgesalmon]

Hello again. I have the above motor I bought used. Don't know when the water pump might have been replaced for sure. PO says probably in 2007 when he had the stator and both switch boxes replaced. It actually is working fine right now but I would like to replace it before I find myself 15 miles out on Lake Michigan and no cooling. I've found the kit on here and the cost is resonable. Just for peace of mind.

40 years ago I lived in CT (Navy submariner) and ran salt water. During that time I replaced water pumps on several OMC engines so I feel confident I can do this. Only thing I'm not sure about is how you disconnect the shifter. On those old OMC's there was a side plate you removed to loosen a connector on the shifter shaft. Can't find anything like that on this merc.

Does the shifter just slide out of the lower unit like the drive shaft? On those old OMC engines the shifter went up and down. On this Merc it turns left and right.

Any info would be appreciated, also any tips.

Thank you

 

[Chris1956]

Re: 1979 merc 115hp water pump replacment?

George, The Merc shift rods slide in-out of a splined connector. On that motor you will have five visible nuts and a hidden bolt (under the zinc anode) that hold the gearcase to the midsection. Put the motor in neutral, tilt it all the way up and remove the nuts. Now use a thin wall 1/2" socket thru the hole in the midsection, to remove the zinc anode bolt. It may have been replaced with a large allen screw. Once the anode is off, you will see the bolt under it.

The gearcase will slide off (hopefully), and you will see the waterpump. replace the impeller, wearplate and all gaskets. Inspect the upper pump stainless insert for scratches.

Grease both driveshaft and shiftshaft splines, for reassembly. Push the gearcase up into the midsection and turn the flywheel a bit until the splines mate. Now use a needle nose plier to mate the shiftshafts. Wiggle the gearcase into place, using nuts and your fingers to hold it. Do not use any tools to force it together, or you can damage the crankshaft splines or driveshaft splines.

 

[Georgesalmon]

Re: 1979 merc 115hp water pump replacment?

Thank you very much. I think I can handle it with that information.