This procedure covers removal and replacement of the coolant bypass pipe on the 3.6L Pentastar V6 engine, which routes coolant between the water pump and thermostat housing.

Warnings

Tools required

Parts

• Coolant bypass pipe × 1 — Mopar 68105583AC or equivalent
• Bypass pipe O-rings × 2 — Usually included with pipe
• Hose clamps (if corroded) × 2 — Use OEM specification

Fluids

• Mopar OAT Coolant (Purple) — 2 qt

Preparation

1. Ensure engine is completely cold to the touch
2. Position vehicle on level ground and engage parking brake
3. Disconnect negative battery cable to prevent fan activation
4. Remove engine cover by pulling upward on four grommet attachments
5. Place drain pan under engine below water pump area

Procedure

1. 1

   Relieve cooling system pressure
   Slowly rotate the radiator cap counterclockwise to the first detent and allow any residual pressure to escape. Once pressure is fully released, press down and continue rotating to remove the cap completely. Set cap aside on a clean surface.
2. 2

   Open bleed screw
   Locate the coolant bleed screw on top of the thermostat housing. Using a flathead screwdriver or 8mm socket, open the bleed screw 2-3 turns to allow air to escape during drain and refill procedures. Leave open for remainder of job.
   ℹ️The bleed screw is plastic. Do not force or overtighten to prevent thread damage.
   Torque spec

   Bleed Screw8 Nm (6 lb-ft)
3. 3

   Drain coolant from engine block
   Open the radiator drain petcock at the bottom of the radiator by turning counterclockwise. Allow approximately 2-3 quarts to drain into the pan. This provides working clearance for bypass pipe removal. Close petcock hand-tight once draining slows to a trickle.
   Torque spec

   Drain Petcock8 Nm (6 lb-ft)
4. 4

   Access bypass pipe area
   The bypass pipe is located on the passenger side of the engine block, below the throttle body and behind the alternator. You may need to remove the upper radiator hose from the thermostat housing for additional clearance. Use hose clamp pliers to release the spring clamp and slide it back on the hose before pulling the hose free.
5. 5

   Release bypass pipe hose connections
   Locate the two rubber hose connections on the bypass pipe: one connects to the water pump inlet, the other to the thermostat housing. Use hose clamp pliers to compress and slide back both spring-type hose clamps approximately 2 inches away from the pipe connections. Twist hoses gently to break seal, then pull off the pipe ends. Expect residual coolant to drain.
   ⚠Hoses may be stuck due to age. Do not use excessive force which can damage the pipe nipples or hoses.
   Torque spec

   Hose Clamps4 Nm (3 lb-ft)
6. 6

   Remove bypass pipe mounting
   The bypass pipe is secured to the engine block with one or two bolts depending on design. Locate and remove the mounting bolt(s) using appropriate socket. Note bolt length and position for reinstallation. Carefully maneuver the pipe out of the engine bay, tilting as needed to clear surrounding components.
7. 7

   Inspect and clean connection points
   Examine the water pump inlet and thermostat housing connection points for corrosion, scale buildup, or damage. Clean both surfaces with a shop towel. Remove old O-rings from the connection points using a pick tool if they did not come out with the old pipe. Do not scratch or gouge the sealing surfaces.
   ⚠Damaged sealing surfaces will cause coolant leaks. Replace water pump or thermostat housing if deep scratches or corrosion damage is present.
8. 8

   Prepare new bypass pipe
   Install new O-rings onto both ends of the new bypass pipe. Lightly coat O-rings with fresh coolant to aid installation and prevent tearing. Verify O-rings are seated properly in their grooves and not twisted.
9. 9

   Install new bypass pipe
   Carefully guide the new bypass pipe into position, aligning both ends with their respective ports on the water pump and thermostat housing. Press pipe firmly into both connections until O-rings seat completely. Install mounting bolt(s) and tighten to secure pipe to engine block. Verify pipe is not stressed or binding.
10. 10

    Reconnect hoses
    Slide both coolant hoses onto the bypass pipe nipples, ensuring they seat fully against the pipe shoulders. Position hose clamps over the hose ends and compress to secure. Verify clamps are positioned properly over the hose barb area. If upper radiator hose was removed, reconnect it to the thermostat housing and secure with its clamp.
    Torque spec

    Hose Clamps4 Nm (3 lb-ft)
11. 11

    Refill cooling system
    Close the radiator drain petcock hand-tight. Using a funnel, slowly pour Mopar OAT purple coolant into the radiator fill neck. Fill until coolant begins to flow from the open bleed screw on the thermostat housing, then continue filling until radiator is full. This may take 2-3 quarts to replace what was drained.
    ℹ️Pour coolant slowly to minimize air pocket formation. Allow time for coolant to settle and air to escape through the bleed screw.
    Torque spec

    Drain Petcock8 Nm (6 lb-ft)
12. 12

    Close bleed screw and top off
    Once solid coolant (no air bubbles) flows from the bleed screw, close it by turning clockwise. Tighten to 8.0 Nm (6.0 lb-ft) using a torque wrench. Top off radiator to the fill neck, then install radiator cap. Fill coolant overflow reservoir to the COLD MAX line.
    Torque spec

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

    Purge remaining air from system
    Reconnect negative battery cable. Start engine and allow to idle with heater set to maximum temperature. Monitor temperature gauge and watch for normal operating temperature. Let engine run for 5-10 minutes while observing the upper radiator hose - it should become hot and firm as the thermostat opens. Listen for coolant circulation sounds.
    ⚠If temperature gauge rises above normal range or warning light activates, shut off engine immediately and recheck coolant level and bleed screw.
14. 14

    Final coolant level adjustment
    After engine reaches operating temperature and cooling fans cycle, shut off engine. Allow to cool for 15 minutes. Carefully remove radiator cap and check coolant level - add coolant if needed to bring to top of fill neck. Reinstall cap. Check overflow reservoir and adjust to COLD MAX line. Reinstall engine cover.

Reassembly

1. Ensure all hose clamps are properly positioned and tight
2. Verify no tools or parts were left in engine bay
3. Wipe down any coolant residue from engine components and frame

Verification

• Check for coolant leaks around bypass pipe connections with engine at operating temperature
• Verify heater produces hot air at idle and while driving
• Monitor coolant level in overflow reservoir over next few days - slight decrease is normal as air purges, but continuous loss indicates a leak
• Confirm temperature gauge reads in normal range during typical driving
• Inspect ground under vehicle after overnight parking for coolant drips

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