Head gasket sealer flush? Help

[Harleymotorcycle]

I bought a truck that had a bad head gasket but eventually got replaced but before they replaced it, it looks like they ran head gasket sealant through it, I recently replaced thermostat and found all this **** in it and was wondering if a coolant flush would be a good idea to flush some of this stuff but it seems pretty stuck on the walls, any suggestions? Ram 1500 2013 5.7L

 

[Mister Luck]

I would be concerned about the H20 pump bearing maybe check that and replace the coolant thermostat.
I might just be resolved with a 5% vinegar 20/80 water fill and flush after removing the thermostat.
Bring the cooling system up to temp for 10 minutes then flush till clear, or fill and bring back up to temperature then drain and repeat till clear.
Don’t drive ( Edit “while preforming the flush” ) and watch your temp gauge (“while preforming the flush” ) never use cold water in or on a hot engine block.
Wait for the engine to cool down bellow 100 before attempting to open a pressurized system.

Use a coolant pressure tester to fill and burp the system each time.

I’d pull the Coolant Temp Sensor and check it for residue.
Use a water pump lubricant on the final fill or change the pump out for added insurance.