Here's why it's so stubborn and what you need to do:
* Years of Build-up: Rust and scale don't just magically appear. It's a gradual process. Years of corrosive chemicals reacting with the metal parts of your engine and radiator have created a thick layer.
* Porous Surfaces: The rust itself is porous and traps the sediment. Simply flushing might move some of the loose material, but the embedded crud will remain.
* Poor Coolant Choice: Using the wrong type of coolant (incorrect concentration, incorrect type for your system's materials) accelerates corrosion.
* Failing Components: A failing water pump or radiator can introduce more contaminants.
How to address this (it's a significant job):
1. Thorough Flush (Multiple Times): You'll need to do more than one flush. Drain the coolant completely. Then, use a radiator flush solution following the instructions carefully. Run the engine for 15-20 minutes with the flush solution circulating. Drain again. Repeat this process at least 2-3 times, or until the drained fluid is relatively clear. Plain water flushes between each chemical flush will help.
2. Consider a Chemical Clean: There are stronger chemical cleaners available for extreme buildup. These are more aggressive and should be used cautiously, following instructions precisely. They can potentially damage seals or hoses if left in too long.
3. Back Flushing: This involves connecting a garden hose to the radiator's drain and flushing backward through the system. This can help dislodge stubborn sediment. However, be very gentle to avoid damaging anything.
4. Pressure Washing (Extreme Cases): In very severe cases, a professional might use a pressure washer to clear the system. This should only be done by someone with experience, as you could easily damage the cooling system.
5. Inspect and Replace Components: After the flushing, carefully inspect the radiator, hoses, water pump, and thermostat for damage or wear. Replace any components showing signs of corrosion, leaks, or wear. A new thermostat is usually recommended during this process.
6. Use the Correct Coolant: Once everything is clean and repaired, use the correct type and concentration of coolant specified for your 1994 Ford Ranger. Using the wrong type can undo all your hard work.
Important Considerations:
* Professional Help: If you're not comfortable working on your cooling system, it's best to take your truck to a mechanic. Ignoring this problem could lead to engine overheating and significant damage.
* Safety First: Allow the engine to cool completely before working on the cooling system. Coolant is toxic and hot coolant can cause serious burns.
This is a significant undertaking. Start with the thorough flushing and assess the situation from there. If the rust and sediment are still heavily present, professional intervention might be the best approach.
