cleaning water jackets

[Astro]

I have ar 230 ho with water flow issues, Temps in the front Cylinder 1 of port engine are up to 185 but much cooler everywhere else ( 90-140). I suspect the water jackets are plugged, especially near cylinder 1 bec its the furthest from the inlet and gets less water pressure. Got stuck on shore end of last season, and im sure i sucked sand into jet pumps.
Im going to try the closed loop flush this weekend but if it doesnt work i wondered if anyone has tried
manually cleaning out the water jackets by removing the water inlet tubes on the side of manifold and poking a long thin stiff flexible wire in the exhaust manifold water inlet tubes < see pic?

 

[Brad_Ct]

This is a picture of an engine I pulled out of our boat because it was overheating. In the upper right you can see that the water jacket is completely plugged, I got some of it out with a thin tool that fit into the jacket.

 

[Astro]

Yeah that's the ultimate remedy. Trying to avoid pulling and disassembling engine or manifold.

 

[Astro]

Seems like this happens a lot near the front # 1 cylinder. Probably because it's the furthest from the raw water inlet and the flush ports. I'm going to do the closed loop flush by Cranky Gypsy with some vibration from impact gun and wood block outside the area to break up the crud.