Freeze plugs and cooling crud. Confused.

[89ARIES]

Also, Butch told me there was a lot of crud and rust in my cooling system, and I should get it cleaned. Does this
involve tearing out the freeze plugs? What is the purpose of the freeze plugs? How do I get the cooling system correctly
cleaned, flushed, and prevent crud and rust buildup in the future?

[Pete in NH]

The plugs many people call freeze plugs are not really there to prevent engine block damage if the water in the block should freeze. They are really core plugs used to fill molten metal pour ports when the block is cast. You do not need to remove them to flush out the cooling system. There are three options in cleaning out a cruddy cooling systems depending on how dirty it is. The first involves a mild cleaner if it is not too dirty. The second is a reverse flushing process and the third involves an acid based cleaner for really dirty blocks. Given the aluminum head I would not used the acid based process, even if it is followed properly with a neutralizer. The reverse flushing process uses a garden hose and some special fittings that can be purchased at your local auto parts supplier.

It's important to always run a 50/50 mix of a good antifreeze with rust inhibitors. Using plain water leads to rust and crud in the cooling system and the heater core may be subject to freezing in A/C equiped cars.