best way to get rust clog out of cooling system

This model had issues with rust buildup in the cooling system. One procedure that I am aware of consisted of removing a couple freeze plugs and running pure water through the system until clean. Install the freeze plugs again and then add a heavy duty rust remover flush and draining it again.

From Ford Program 98B23 (now long since expired...): "Engine cooling system flow imbalance and aeration may lead to a discoloration of the coolant. Vehicle owners may also describe additional cooling system concerns, including coolant overflow, coolant smell, lack of heat, coolant leaks or high temperature gauge readings. Affected owners are notified to return their vehicle for an inspection and/or installation of a coolant by-pass kit. Dealers are instructed to inspect the vehicle for previous installation of a coolant by-pass kit (TSB Article 97-24-16). If the vehicle does not have a by-pass kit installed, dealers are instructed to install the by-pass kit. If the coolant meets specific degradation criteria, dealers are instructed to also flush the cooling system. The following parts are used for the service: F7DZ-8522-AB Coolant By-Pass Kit (3.0L Gasoline and Ethanol Engines) E2FZ-19549-B Coolant (6 quarts required) F8DZ-6C057-AA Core Plug FW-16 Coolant Additive F8AZ-19A503-AA Neutral pH Iron Cleaner The iron cleaner is a help in reducing the contaminants.