Ford — Cooling System Flush, Block Heater And Heater Core Replacement

Repair & overhaul · cooling system / heater core

From a Ford service manual — check it applies to your exact model before use.

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Procedure

1. Drain the cooling system. On the 5.0L engine, remove the coolant hoses from the transmission fluid warmer.
2. Remove the thermostat and disconnect the lower radiator hose.
3. Using a garden hose, flush the inlet and outlet radiator hoses for 2 minutes each.
4. Reassemble the thermostat housing without the thermostat. Flush the degas bottle for 2 minutes. Close the radiator drain valve.
5. Disconnect the inlet and outlet heater core hoses. Flush the heater hoses back toward the engine for 5 minutes each.
6. Reattach all hoses except the inlet and outlet heater hoses. Clamp off the heater hoses with pinch pliers.
7. Add 1 bottle of Motorcraft® Premium Cooling System Flush and fill the rest of the cooling system with water.
8. Run the engine at 2,500 RPM for 15 minutes with the climate control off. Return to idle and command cooling fans on high for 5 minutes.
9. Turn the engine off and open the degas bottle cap carefully. Drain the cooling system.
10. Flush the degas bottle at the cap opening for 2 minutes. Close the radiator drain valve. Fill the cooling system with water.
11. Repeat Steps 20 through 27. Remove pinch pliers and backflush the heater core hoses toward the engine for 1 minute each.
12. Remove the block heater and allow the block to drain. Install the thermostat.
13. Inspect the block heater. If stainless steel (CV6T-6A051-AA or HL3T-6A051-AB) reinstall; if brass (94BB-6A051-AA) install a new revised block heater.
14. Remove the block heater wire harness and install the new block heater wire harness following the same routing.
15. Replace the heater core. Clean the heater core inlet and outlet metal tubes with hot water until free of deposits.

Source: Ford service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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