Cleaning out years of gunk from coolant galleries

jamesinc

I want to clear the gunk out of my coolant galleries without having to hot-tank the block (as this would mean having to disassemble the entire block)

This is what it looks like:

Any ideas? A pipe cleaner might get things started, but there are many areas I cannot access easily. CLR maybe?

egads (she/her)

Coolant flush magic liguid stuff?

jamesinc

I actually had good success with a high pressure washer and some compressed air!