9.9 Merc 4 stroke Low Cooling Flow

[Kisinana]

Maybe someone has the same problem or has had. My kicker has very little water come out at idle, you can feel air passing through it. Seems to work fine at about 2x idle speed although it does have gaps where the flow slows. I have replaced the impeller and the thermostat and have flushed the water system. There is a slight increase, but very little. Can the pump be bypassing? It does not seem worn and the impeller I took out was not worn either,
Any ideas?

 

[Hookin'up]

I had the exact same issue on my merc 9.9 4 stroke even after a new impeller and I ended up replaceing the complete water pump assy from merc and it fixed the problem, try cleaing out the tell tale tube first
you may have a spider or something in it blocking the passage, I guess my waterpump housing was warped or something never really did see anything drastically wrong with it
but the new assy sure fixed it up in a hurry

 

[willydw]

I spray wd 40 in the tell tale using the plastic straw. Works great