90 Merc 115 alarm. Help!

[narmer2000]

Installed a new water pump and thermostat per the seloc instruction manual. Put the muffs on, turned on the water and started motor. Runs fine for about 5 minutes when the alarm goes off. There is a small hose end on the motor cover that I think water is supposed to pee out of when the motor runs but all I get is air. Any suggestions or should this thing go to the shop?

 

[CharlieB]

Re: 90 Merc 115 alarm. Help!

First suspect is that the impeller key slipped out of place as you slid the impeller down. Use a small dab of grease to stick the key to the shaft while you slide the impeller down over it, then give a twist to the impeller so that you can be sure to feel that the key positively locks the impeller to the shaft.

Second possibility is that you missed aligning the water transfer tube into the top of the water pump.

Both require you to drop the foot again to make sure.

 

[narmer2000]

Re: 90 Merc 115 alarm. Help!

Thanks Charlie. What do you mean aligning water tube? I didnt see a tube or is it up inside the unit? And am I correct that the small hose end should pee water?

 

[CharlieB]

Re: 90 Merc 115 alarm. Help!

When you drop the lower unit off, look up inside the motor leg, you should see a copper tube that was supposed to slid into the top of the water pump. This 'transfer tube' is the path for the water to go up into the engine, if you do not make sure that this tube fit into the water pump, then all the water will just fall straight out with going up, into, and cool the motor.

Many motors have a plastic guide tube that will sit on top of the water pump to extend the pump outlet higher, making it easier to be sure the transfer tube is guided into the pump as you raise the gearcase.

It is an easy mistake to make but now you will never forget.

While you have the gearcase down it would still be a good idea to double check the impeller key. Just to be sure.