Originally Posted by
geezer101
Grrr, that stuff is the bane of all good things. So this garbage is also floating around inside your block, head and heater core. It kills thermostats and heater control valves too with surprising efficiency (bonus points if you have the factory carb with the water choke) Apparently it's near impossible to completely remove it. I think at this moment you will have to use desperate measures to get rid of it. Pull the heater out and bath the core in citric acid and flush the heater valve (citric acid is way cheaper than CLR and isn't a disaster to dispose of). This is a good opportunity to give the heater/blower case an epic clean and replace all of the control flap seals. Remove the thermostat and reverse flush the engine. Don't use coolant for a while - distilled water only. Drive it for a few weeks/a month, flush again, rinse, repeat. Expect to find out why this crap was used on the engine in the first place (bad head gasket, undetected leak in the external water recirculation pipe, pinhole leak in the base plate of the intake manifold - this one is common on 2.0 G63B engines)