03 4strk 25 Merc cooling system clogged.

[Backchannelmako]

4 stroke Merc 25.
After replacing the waterpump impeller I discovered I was not pumping water. Motor overheating, indicator not clogged.
I took lower unit off motor and blew compressed air up the water tube. With the thermostat out, I could not get air to move freely through the cooling system. I could hear a slight bubbling in the engine block. Looking for some good ideas on how to unclog the system.

 

[bilge rat jim]

You could start by removing the water tube from the block and checking for restrictions in the water tube.

 

[Backchannelmako]

Just pull as hard as I can on it? I pulled on it pretty hard and second guessed myself wether it comes out like a two stroke or not.

 

[bilge rat jim]

Sorta- tilt the outboard full up, spray some soapy water up the driveshaft housing for lube, and wiggle, turn, and pull at the same time.