Merc 1998 ELPT 25, No telltail/cooling water flow. Impeller & gaskets replaced.

[Joatman]

Bought this engine used. Should have heard/watched it run first. There's no water flow up to the thermostat housing. I replaced the impeller and pump gaskets. Starts right up. No cooling water flow to powerhead even if I rev it for a second. Using muffs, plenty of hose pressure/flow, with lower unit IN a garbage can full of water. I'm totally baffled. Anyone have any ideas?

 

[wn6ngp]

Have you tried putting the motor in the lake. I have mixed results using the ear muffs.

Does the motor overheat? It will get hot within a few minutes if you don't have water getting to the top.

You may have something clogging the tell tail hose. That happened to me when I had to plow thru a sand bar. the tell tail quit but the motor did not overheat. Don't get me wrong, I was plenty worried but I didn't have a choice in the middle of the bay. After a few minutes the clog came loose and tell tail was spewing.

 

[Joatman]

"There's no water flow up to the thermostat housing." I'm pretty sure the tell-tail tube is downstream from the thermostat housing.

" Using muffs, plenty of hose pressure/flow, with lower unit IN a garbage can full of water." That's about as much as I can simulate the boat being in the lake as possible.

I'm not running it long enough to overheat, but even a few revs, run for at least a couple minutes, I should have water flow up to the thermostat. Thermostat, port and housing are dry as a bone inside.

 

[Little Richard]

Pull lower unit back off check and make sure key is in proper place. See if key has sheered inside of impeller. If it's easy to remove thermostat use water hose and flush the system thru all orfices all ways. See if you have a clog. Reinstall lower unit and thermostat and see. Make sure your impellers vanes are turned in the housing correctly. As you slide housing down turn driveshaft with your hand clockwise and let vanes fold back into housing. Make sure your intake tube is inserted properly into pump housing.

 

[Little Richard]

Check screens on lower unit water intakes

 

[flyingscott]

Check the watertube make sure it is in correctly they like to come out with the pump housing. If that is in correctly put the hose up to the tube and see if water comes out that way. That motor will not have full flow until the thermostat opens but it should dribble out until t opens. Also check the key in the impeller and make sure it's in. Also did you put the washers on the impeller?