water problem with '89 rude 25hp

[bluegillfisher]

I can not get water out the tell. I replaced impeller. Still no water. I took off small hose coming off engine(it was clogged with mud) and while my lower unit was off I put water up the copper line going to top of engine. I at first didn't get water out the tell, but it opened up and water came out. When I put the lower unit back on, no water out the tell. I am using muffs to test motor as I don't have a tank. I am afraid that there is more of the mud(probably insect stuff) inside the motor. I don't know what steps I should take now. How do I clean all of the passages?
Please help.