Replace a single freeze plug on the 3.5L EcoBoost engine, requiring partial drivetrain component removal for access and coolant system drainage.

Warnings

Tools required

Parts

• Engine freeze plug (cup type) × 1 — Use OEM specification for 3.5L EcoBoost
• Engine coolant × 1 — Motorcraft Orange Premium Gold Coolant VC-7-B
• High-temperature RTV sealant × 1 — Motorcraft TA-357 or equivalent
• Engine gasket (if damaged during removal) × 1 — Use OEM specification

Fluids

• Motorcraft Orange Coolant — 13 qt

Preparation

1. Verify engine is completely cool to the touch
2. Position vehicle on level surface and engage parking brake
3. Disconnect negative battery cable and secure away from battery terminal
4. Remove engine cover by pulling upward on clip points
5. Place large drain pan underneath radiator and engine
6. Document freeze plug location with photos for reference during reassembly

Procedure

1. 1

   Drain cooling system
   Open radiator petcock valve at bottom of radiator. Remove coolant reservoir cap to allow air entry and faster drainage. Once radiator is drained, locate and remove engine block drain plug on lower side of engine block. Collect all coolant for proper disposal. Allow system to drain completely for 15-20 minutes.
2. 2

   Remove air intake system
   Loosen clamps on air intake tube. Disconnect mass airflow sensor electrical connector. Remove air filter housing bolts and lift entire air intake assembly away from engine bay. Set aside in clean area.
3. 3

   Remove intercooler system components
   Disconnect charge air cooler tubes from turbocharger outlets and throttle body. Remove mounting bolts securing intercooler pipes to engine. Note routing of coolant lines to charge air cooler and disconnect at quick-connect fittings. Remove intercooler assembly to improve access to rear of engine.
   Torque spec

   Mounting Bolts31 Nm (23 lb-ft)
4. 4

   Remove accessory components for access
   Identify which freeze plug requires replacement and determine access path. For rear engine plugs, remove starter motor by disconnecting electrical connections and removing mounting bolts. For side plugs, remove alternator or A/C compressor mounting bolts and reposition components without disconnecting lines. Support components with wire or bungee cords.
   Torque spec

   Mounting Bolts31 Nm (23 lb-ft)
5. 5

   Remove failed freeze plug
   Using punch and ball peen hammer, carefully drive one edge of freeze plug inward to create a tilt. Do not puncture through the plug completely. Once tilted, use pliers or pry bar to grip raised edge and pull freeze plug from block. Work carefully to avoid damaging the freeze plug bore in engine block casting.
6. 6

   Prepare freeze plug bore
   Use wire brush to thoroughly clean freeze plug bore in engine block. Remove all rust, old sealant, and corrosion. Use gasket scraper to ensure bore surface is completely clean and smooth. Inspect bore for cracks or damage. Wipe bore clean with lint-free cloth and allow to dry completely. Bore must be free of oil, coolant, and debris for proper seal.
7. 7

   Apply sealant and install new freeze plug
   Apply thin continuous bead of high-temperature RTV sealant around outer edge of new freeze plug as specified in torque specifications. Position freeze plug in bore with convex (domed) side facing outward. Using freeze plug installer tool matched to plug diameter, carefully drive plug into bore. Tap evenly around perimeter to ensure plug seats squarely and flush with block surface. Final installation depth should be 1-2mm below block surface.
   Torque spec

   Freeze Plug10 Nm (7 lb-ft)
8. 8

   Reinstall accessory components
   Reinstall starter motor, alternator, A/C compressor, or other components removed for access. Ensure all electrical connections are secure and routing matches original configuration. Torque all mounting bolts to specification.
   Torque spec

   Mounting Bolts31 Nm (23 lb-ft)
9. 9

   Reinstall intercooler system
   Reconnect coolant lines to charge air cooler using new O-rings if applicable. Reinstall intercooler pipes and charge air cooler tubes. Ensure all clamps are positioned correctly and tightened securely. Torque mounting bolts to specification.
   Torque spec

   Mounting Bolts31 Nm (23 lb-ft)
10. 10

    Reinstall air intake system
    Position air filter housing and intake tube assembly. Connect mass airflow sensor electrical connector. Tighten all clamps and secure any clips. Ensure no vacuum leaks are present at connections.
11. 11

    Refill cooling system
    Close radiator petcock and install engine block drain plug. Fill cooling system with 50/50 mix of Motorcraft Orange Coolant and distilled water through radiator and coolant reservoir. Total system capacity is 13 quarts. Fill slowly to allow air pockets to escape. Fill to MAX line on coolant reservoir.
12. 12

    Bleed cooling system
    With radiator cap still off, start engine and allow to idle. Monitor coolant level and add as needed while engine warms. Run heater at maximum temperature to circulate coolant through heater core. Squeeze upper radiator hose to help purge air bubbles. Once engine reaches normal operating temperature and thermostat opens, top off coolant and install radiator cap. Add coolant to reservoir MAX line.
13. 13

    Check for leaks and verify repair
    Allow engine to reach full operating temperature while monitoring for leaks at freeze plug location. Inspect all connections disturbed during repair. Check coolant level after engine cools and top off if necessary. Reconnect negative battery cable and reinstall engine cover.

Reassembly

1. Allow RTV sealant to cure for minimum 30 minutes before refilling coolant system
2. Replace any gaskets or seals that were damaged during disassembly
3. Verify all electrical connectors are fully seated with locking tabs engaged
4. Double-check all fasteners are torqued to specification before starting engine

Verification

• Start engine and verify no coolant leaks at freeze plug location after reaching operating temperature
• Check that coolant level remains stable in reservoir after complete heat cycle
• Monitor engine temperature gauge to ensure proper cooling system operation
• Verify no warning lights on instrument cluster related to cooling system
• Inspect underneath vehicle for any coolant drips after test drive
• Recheck coolant level after 24 hours of operation and top off if needed

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