Replace the coolant bypass pipe on the 3.5L EcoBoost V6 engine, which routes coolant between the engine block, water pump, and thermostat housing.

Warnings

Tools required

Parts

• Coolant bypass pipe × 1 — Use OEM Ford part
• Bypass pipe O-rings × 3 — Usually included with bypass pipe
• Thermostat housing gasket × 1 — Use OEM specification
• Motorcraft Orange Coolant concentrate × 1 — VC-7-B

Fluids

• Motorcraft Orange Coolant — 4 qt

Preparation

1. Ensure the engine is completely cold to the touch
2. Park vehicle on level ground and engage parking brake
3. Disconnect the negative battery cable to prevent accidental fan activation
4. Remove the engine cover by pulling upward on the front corners
5. Place a large drain pan beneath the radiator drain petcock

Procedure

1. 1

   Drain the cooling system
   Slowly open the radiator drain petcock located at the bottom driver side of the radiator. Allow coolant to drain into the collection pan. If equipped, open the cooling system bleed screw on top of the radiator or thermostat housing to accelerate draining. Drain until coolant flow stops significantly.
   Torque spec

   Drain Petcock8 Nm (6 lb-ft)

   Bleed Screw8 Nm (6 lb-ft)
2. 2

   Remove air intake components for access
   Disconnect the mass airflow sensor electrical connector. Loosen the clamp at the throttle body and turbocharger inlet. Remove the air intake tube assembly to improve access to the driver side of the engine. Set aside in a clean area.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
3. 3

   Disconnect coolant hoses from bypass pipe
   Locate the coolant bypass pipe on the driver side of the engine. Using hose clamp pliers, compress and reposition the spring clamps on the upper and lower coolant hoses connecting to the bypass pipe. Twist and pull the hoses to disconnect them from the pipe. Be prepared for residual coolant spillage.
4. 4

   Remove thermostat housing bolts
   The bypass pipe connects to the thermostat housing with two or three bolts depending on configuration. Using a 10mm socket, remove the thermostat housing bolts that secure the bypass pipe connection point. Keep track of bolt locations as they may be different lengths.
   Torque spec

   Housing Bolts16 Nm (12 lb-ft)
5. 5

   Disconnect bypass pipe from water pump
   The bypass pipe inserts into the water pump housing with an O-ring seal. Carefully wiggle and pull the bypass pipe to separate it from the water pump. The pipe may be stuck due to O-ring compression; use gentle twisting motion while pulling. Avoid using excessive force that could damage the water pump housing.
6. 6

   Remove bypass pipe from engine block connection
   The bypass pipe also connects to the engine block with another O-ring seal. Carefully maneuver the pipe out of the engine bay, disconnecting it from the block port. Note the orientation and routing of the pipe for installation of the new part.
7. 7

   Clean sealing surfaces
   Using a razor blade or gasket scraper, carefully clean all old gasket material and O-ring residue from the water pump housing, engine block port, and thermostat housing mating surfaces. Ensure surfaces are completely clean and dry. Inspect the ports for any damage or cracks.
8. 8

   Install new O-rings on bypass pipe
   Lubricate the new O-rings with fresh coolant and install them into the grooves on the new bypass pipe. Ensure O-rings are properly seated in their grooves and not twisted. Install O-rings on all three connection points: water pump end, block end, and thermostat housing end.
9. 9

   Install new bypass pipe
   Carefully route the new bypass pipe into position, aligning it with the engine block port first. Push firmly to seat the O-ring into the block. Then align and push the water pump end into the water pump housing until the O-ring is fully seated. Finally, position the thermostat housing connection.
10. 10

    Install thermostat housing bolts
    Install the new thermostat housing gasket if required. Position the thermostat housing against the bypass pipe connection and install the mounting bolts finger tight. Torque the thermostat housing bolts in a criss-cross pattern to specification using a torque wrench.
    Torque spec

    Housing Bolts16 Nm (12 lb-ft)
11. 11

    Reconnect coolant hoses
    Reconnect the upper and lower coolant hoses to the bypass pipe. Ensure hoses are pushed fully onto the pipe nipples. Reposition the spring clamps over the hose connections using hose clamp pliers. Verify clamps are positioned in the proper groove on each connection.
12. 12

    Reinstall air intake components
    Reinstall the air intake tube assembly, ensuring proper alignment at both the throttle body and turbocharger inlet. Tighten the clamps securely. Reconnect the mass airflow sensor electrical connector until it clicks into place.
    Torque spec

    Hose Clamps3 Nm (2 lb-ft)
13. 13

    Close drain and fill cooling system
    Close the radiator drain petcock hand tight. Mix Motorcraft Orange Coolant 50/50 with distilled water or use pre-diluted coolant. Slowly fill the cooling system through the degas bottle until coolant reaches the MAX COLD fill line. Leave the bleed screw open during filling to allow air to escape. Close the bleed screw when coolant flows from it without air bubbles.
    Torque spec

    Drain Petcock8 Nm (6 lb-ft)

    Bleed Screw8 Nm (6 lb-ft)
14. 14

    Bleed air from cooling system
    Reconnect the negative battery cable. Start the engine and allow it to idle with the degas bottle cap off. Run the engine until the thermostat opens (cooling fans cycle on). Monitor coolant level and add as needed to maintain proper level. Squeeze the upper radiator hose several times to help purge air bubbles. Reinstall the degas bottle cap once the system is fully bled.

Reassembly

1. Verify all hose clamps are properly positioned and secure
2. Reinstall the engine cover by aligning the grommets and pressing down until seated
3. Double-check that the mass airflow sensor connector is fully seated
4. Ensure no tools or parts were left in the engine bay

Verification

• With the engine at operating temperature, inspect all bypass pipe connections for coolant leaks
• Check coolant level in the degas bottle when cold - should be at MAX COLD line
• Verify heater output is hot, indicating proper coolant circulation
• Monitor coolant level over the next few days and top off as needed as residual air purges from the system
• Check for any error codes related to engine temperature using an OBD-II scanner

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