Mercury 135 Black Max outboard v6 cooling

[Officerelmore]

I have a 135 black max outboard v6. I ran up on a sand bar the other day (flooding changed the river up quite a bit) and then noticed that my tell tale spout wasn't shooting water out. I pulled the cowling off and cheked the tube and found a small pebble in the nipple blocking flow. I pulled it out and it went back to working again. A while later it did the same thing. I checked again and sure enough there was another pebble in it. I removed it and started paying alot closer attention. I noticed that the tell tale tube water was very hot and there was alot of steam coming out. The water pressure is still good. I pulled the thermostat housings off and saw a bunch of dirt and corrosion on walls of the water jackets. I also noticed that the thermostats had been modified to allow water to flow not matter what temp it was.

My question is how should I go about cleaning the water jackets. Obviously I'm going to replace the water pump and thermostats, but what can I do to clean the rest?

 

[Texasmark]

Might as well pull your lower unit and have a look at your water pump. While it's off, you can reverse pressure wash your cooling passages in the block by shooting your hose through the tstat holes while the water pump and lower unit are removed. Also, while your stats are out you can flush out your tell tale tubes. Only thing left is your exhaust manifold plate cooling that is a separate circuit. So to flush that you need to shoot water up the copper tube that connects from the water pump output to the bottom of the engine block/midsection top......while your lower unit is off.

 

[Chris1956]

Also, remove and clean the poppit valve on the lower starboard side of the motor.

 

[Texasmark]

Also, remove and clean the poppit valve on the lower starboard side of the motor.

OOps, I forgot that.