This procedure covers removal and replacement of the coolant bypass pipe on the 5.0L Coyote V8 engine, which connects coolant flow between the water pump and thermostat housing.

Warnings

Tools required

Parts

• Coolant bypass pipe × 1 — Use OEM specification
• Bypass pipe O-rings × 2 — Usually included with pipe
• Hose clamps × 2 — Use OEM specification if damaged

Fluids

• Motorcraft Orange Coolant — 2 qt

Preparation

1. Ensure engine has been off for at least 2 hours and is completely cool to the touch
2. Park vehicle on level ground and engage parking brake
3. Disconnect negative battery terminal to prevent accidental electrical activation
4. Remove engine cover by lifting upward on front edge then pulling forward
5. Remove intake manifold assembly following appropriate service procedure - this is required for access to the bypass pipe
6. Place drain pan under radiator drain petcock
7. Open radiator drain petcock and drain approximately 2 quarts of coolant into drain pan
8. Close drain petcock after partial coolant drain

Procedure

1. 1

   Locate and inspect bypass pipe
   With the intake manifold removed, locate the coolant bypass pipe in the engine valley. It runs between the water pump housing on the front of the engine and the thermostat housing. Inspect the surrounding area for coolant residue to confirm the leak location. The bypass pipe has rubber hose connections at each end secured with hose clamps.
2. 2

   Disconnect forward hose connection
   Using hose clamp pliers or a flat blade screwdriver, loosen the hose clamp at the water pump end of the bypass pipe. Slide the clamp away from the connection point. Gently twist and pull the hose off the bypass pipe fitting. If the hose is stuck, use a small pick to break the seal between the hose and pipe. Be prepared for residual coolant drainage.
   ⚠Do not pry against aluminum engine components as they damage easily. Use only plastic or brass tools if prying is necessary.
3. 3

   Disconnect rear hose connection
   Loosen the hose clamp at the thermostat housing end of the bypass pipe using the same method. Slide the clamp back along the hose. Twist and pull the hose off the bypass pipe rear fitting. Have shop towels ready to catch any remaining coolant.
4. 4

   Remove bypass pipe mounting hardware
   Locate the mounting bracket bolt(s) that secure the bypass pipe to the engine block. Typically there is one 8mm bolt securing a support bracket. Remove this bolt and any associated clips or brackets. Keep all hardware organized for reinstallation.
5. 5

   Extract bypass pipe
   Carefully maneuver the bypass pipe out of the engine valley. The pipe may need to be rotated or angled to clear surrounding components. Note the routing and orientation for installation of the replacement pipe. Inspect the removed pipe for cracks, corrosion, or O-ring damage.
6. 6

   Clean mating surfaces
   Using a wire brush and shop towels, thoroughly clean the pipe fittings on both the water pump housing and thermostat housing where the hoses connect. Remove all old coolant residue, corrosion, and debris. Ensure the surfaces are clean and dry for proper seal of the new O-rings.
7. 7

   Prepare new bypass pipe
   Inspect the new bypass pipe and verify it includes new O-rings. If O-rings are separate, install them onto the pipe fittings at both ends. Lightly lubricate the O-rings with fresh coolant to ease installation and prevent tearing. Do not use petroleum-based lubricants.
8. 8

   Install new bypass pipe
   Carefully position the new bypass pipe into the engine valley, routing it in the same path as the original. Ensure the pipe is oriented correctly with both ends aligned to their respective connection points. Install any mounting brackets and secure with the 8mm bolt, tightening to a snug fit but not fully torquing yet.
9. 9

   Connect hoses to bypass pipe
   Push the coolant hoses firmly onto both ends of the new bypass pipe until they seat completely against the pipe shoulders. Ensure each hose is fully engaged. Position the hose clamps over the hose-to-pipe connection points.
   ℹ️Hose clamps should be positioned approximately 1/4 inch from the end of each hose for optimal sealing.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
10. 10

    Secure all connections
    Tighten all hose clamps to 3.0 Nm (2.0 lb-ft). If using worm-drive clamps without torque capability, tighten until snug plus 1/4 turn. Verify the bypass pipe mounting bracket bolt is secure. Double-check that all connections are properly seated.
    Torque spec

    Hose Clamps3 Nm (2 lb-ft)
11. 11

    Reinstall intake manifold
    Following the appropriate service procedure, reinstall the intake manifold assembly. Ensure all gaskets are new and properly positioned. Torque all intake manifold bolts to specification per the intake manifold service procedure.
12. 12

    Refill cooling system
    Using a funnel, add Motorcraft Orange Coolant to the cooling system through the degas bottle. Fill to the cold fill line. Locate the bleed screw on the thermostat housing and open it slightly. Continue adding coolant until air-free coolant flows from the bleed screw, then close the bleed screw to specification.
    Torque spec

    Bleed Screw8 Nm (6 lb-ft)
13. 13

    Purge air from cooling system
    Start the engine and allow it to reach normal operating temperature with the heater set to maximum temperature. Monitor coolant level in the degas bottle and add coolant as the level drops due to air purging. Run the engine for 10-15 minutes until the thermostat opens and coolant circulates fully. Shut off the engine and allow to cool for 30 minutes, then recheck coolant level and top off as needed.

Reassembly

1. Ensure all hose clamps are properly tightened and positioned over the connection areas
2. Verify the bypass pipe mounting bracket is secure and the pipe is not contacting any moving components
3. Reinstall engine cover by aligning rear tabs first, then pressing down on front edge until it clicks into place
4. Reconnect negative battery terminal and tighten securely

Verification

• With engine at operating temperature, visually inspect the bypass pipe connections in the engine valley for any signs of coolant leakage using a flashlight
• Check coolant level in the degas bottle after the engine has fully cooled - it should be at the cold fill line
• Verify heater output is strong and consistent, indicating proper coolant flow through the bypass circuit
• Monitor coolant level over the next few days of driving and check for leaks, topping off as necessary until the system stabilizes
• Scan for diagnostic trouble codes related to cooling system operation - there should be no codes present

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