Coolant Flush

Complete coolant system drain, flush, and refill procedure for the 1992 Dodge Viper 8.0L V10, including air bleeding to prevent overheating.

Warnings

Tools required

Parts

• Engine block drain plug washer × 1 — Use OEM specification

Fluids

• Ethylene glycol 50/50 coolant — 24 qt

Preparation

1. Park vehicle on level surface and allow engine to cool completely (minimum 2 hours).
2. Verify engine is cold by touching upper radiator hose.
3. Gather all tools, parts, and fluids before starting.
4. Position drain pan under radiator drain location.
5. Have approximately 10 gallons of distilled water available if performing thorough flush.

Procedure

1. 1

   Remove radiator cap and open drain system
   Remove the radiator cap slowly by turning counterclockwise. If any pressure is present, stop and allow more cooling time. Locate the radiator drain petcock at the bottom driver's side of the radiator. Position drain pan beneath petcock and open by turning counterclockwise. Allow coolant to drain completely into pan.
2. 2

   Drain engine block
   Consult the factory service manual to locate the engine block drain plug(s) for the 8.0L V10 (location and fastener type must be verified). If equipped, remove the drain plug using the appropriate tool and allow block coolant to drain. If the plug uses a sealing/crush washer, remove and discard the old washer.
3. 3

   Remove lower radiator hose (optional for thorough flush)
   If performing a thorough flush, use hose clamp pliers or appropriate tool to release the clamp on the lower radiator hose at the radiator connection. Remove the hose and direct it into the drain pan. This allows better flushing flow through the system.
4. 4

   Flush cooling system (if desired)
   Insert garden hose into radiator fill neck or upper radiator hose connection. Run water through system until discharge runs clear from radiator drain petcock and/or lower hose connection. For engine block, temporarily install drain plug and fill through radiator, then drain again to flush block passages. Repeat until water runs clear.
5. 5

   Reinstall block drain plug
   Install new crush washer onto block drain plug. Thread drain plug into block by hand until seated, then torque to specification.
   Torque spec

   Block Drain Plug25 Nm (18 lb-ft)
6. 6

   Reconnect lower radiator hose (if removed)
   If lower radiator hose was removed, reinstall it onto the radiator outlet fitting. Position the hose clamp over the connection area and tighten to specification.
   Torque spec

   Coolant Hose Clamps4 Nm (3 lb-ft)
7. 7

   Close radiator drain petcock
   Turn the radiator drain petcock clockwise until hand tight. Do not overtighten as this can crack the plastic petcock.
   Torque spec

   Drain Petcock5 Nm (4 lb-ft)
8. 8

   Locate and open bleed screw
   Refer to the factory service manual for the correct air-bleed procedure. If the vehicle is equipped with a coolant bleed screw (location per FSM), open it 2-3 turns to allow air to escape during filling. If no bleed screw is present, follow the manual's fill-and-burp procedure.
9. 9

   Fill cooling system with coolant
   Using a funnel, slowly pour 50/50 premixed ethylene glycol coolant into the radiator fill neck. Fill slowly to allow air to escape through the open bleed screw. Continue filling until coolant flows from the bleed screw without air bubbles. Verify the total system capacity against the factory service manual before purchasing coolant.
10. 10

    Close bleed screw and complete fill
    Once coolant flows steadily from bleed screw without air bubbles, close the bleed screw to specification. Continue filling radiator to the base of the fill neck. Install radiator cap.
    Torque spec

    Bleed Screw7 Nm (5 lb-ft)

    Radiator Cap1 Nm (1 lb-ft)
11. 11

    Initial engine warm-up and burping
    Start engine and allow to idle. Monitor temperature gauge. As engine warms, watch for coolant level drop in radiator (may need to remove cap and add more coolant). Run engine until thermostat opens (approximately 195°F) and upper radiator hose becomes hot. Check for leaks at drain plug, petcock, and hose connections.
    ⚠Monitor temperature gauge closely during this step. If temperature rises above normal operating range, shut down immediately and recheck for air pockets or leaks.
12. 12

    Final bleeding and top-off
    With engine at operating temperature, shut off engine and allow to cool for 15 minutes. Carefully remove radiator cap (some pressure may be present). Check coolant level and top off to base of fill neck if needed. If significant air was released, briefly open bleed screw again, start engine, and verify solid coolant flow before closing. Reinstall radiator cap securely.

Reassembly

1. Verify radiator cap is properly seated and locked.
2. Wipe down any coolant residue from engine and frame components.
3. Check ground under vehicle for any drips or leaks.

Verification

• Start engine and verify temperature gauge reaches normal operating range (approximately 195-210°F).
• Check that both upper and lower radiator hoses become hot, indicating proper circulation.
• Verify no leaks at drain plug, petcock, hoses, or bleed screw.
• After engine cools, recheck coolant level in radiator (should be at base of fill neck).
• Test drive vehicle and monitor temperature gauge under normal driving conditions.
• Recheck coolant level after 24 hours of operation and top off if necessary.

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