M40D2 water system question

[LukeFishWalker]

Sea Rider,
I have no intention of operating it without a thermostat.
As far as the previous operating conditions:
The power head ( I Replaced The Original ) came from the Galveston
Texas area and that's predominately salt water.
I took off the lower unit off & thermostat and hooked a
20GPM electric pump with a hose and connected to the
pick up pipe and ran 30% vinegar throughout the
water system for 45 minutes.
Then flushed with clean water,
then flushed with a concentrated baking soda bath.
After it was all said & done I had 4 level tablespoons of scale
that was left in the barrel once I poured the water out real slow,
Then I pulled the thermostat housing off and forced water
in the block ( Pre Thermostat ) then in the pick up pipe repeating
this step several times.
I forced water into the tattle tail pipe and through the cylinder head
( Post Thermostat ) and repeated this step several times.
My only other option is to pull the powerhead and visually inspect
the 2 holes in the lower block and the galley in the partition
that separates the water to the cylinders & exhaust manifold.
In the picture below:
Red Circle = Passage Into Cylinder Block
Yellow Circle = Passage into Exhaust Manifold
Black Circles = Galley " Restriction " In Partitions

 

[Sea Rider]

If the posted upper pic belongs to the new replaced powerhead the water passages doesn't look in mint clean condition, has the exhaust cover and cylinder head been removed and their water passages cleaned out by manual scraping ? Can flush all day long al water passages with whatever product you like but when having already excessive scale formations such products won't do much nor clean that deep the hidden water passages.



This pic shows the condition of an exhaust chamber religiously flushed with fresh water for 10 minutes soon after the combo returned to terra firme...

Happy Boating​

 

[LukeFishWalker]

Update:
After a week of being in bed due to a stomach virus,
I was able to finally get out of the house and run the
Starbrite De-Scaler through this motor.
I took off the gearcase and hooked the submersible
pump directly to the water inlet pipe.
Loaded the barrel with a 1 to 1 solution and started the
pump - Then cranked the motor. I ran the motor for about
5 or 6 minutes until the solution was no longer cold.
Turned the motor & pump off and drained everything.
Ran clean water through the pump for about 10 minutes.
Then put the gearcase back on and put the motor back
into the barrel with fresh water and cranked it.
Instantly the tattle tail was back to normal and no more
water coming out the weep hole.
I want to thank everyone for their advice.
Lukus