Coolant Flush

Complete coolant system flush and refill for the 2005 Dodge Viper 8.3L V10, including drain, flush, and bleeding procedures to maintain optimal engine cooling performance.

Warnings

Tools required

Parts

• Radiator drain plug washer × 1 — Use OEM specification

Fluids

• Zerex G-05 HOAT 50/50 coolant — 19 qt

Preparation

1. Park vehicle on level surface and apply parking brake. Chock rear wheels.
2. Ensure engine is completely cold to the touch before beginning work.
3. Remove engine cover by releasing clips at each corner and lifting away.
4. Place drain pan(s) with sufficient capacity beneath radiator and engine block drain locations.
5. Have all replacement coolant on hand before starting - approximately 19 quarts of Zerex G-05 HOAT 50/50 pre-mixed coolant.

Procedure

1. 1

   Release cooling system pressure
   Slowly rotate the pressure cap on the coolant expansion tank 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 in a clean location.
2. 2

   Drain radiator
   Locate the radiator drain petcock at the bottom driver's side corner of the radiator. Position drain pan beneath the petcock. Rotate the petcock counterclockwise to open. Allow coolant to drain completely into the pan. On this platform, the drain petcock is plastic and can be fragile - use moderate hand pressure only.
3. 3

   Drain engine block
   Locate the engine block drain plug(s) per the factory service manual for the 8.3L V10. Using an appropriate socket, remove the block drain plug(s) and allow coolant to drain from the engine block. Inspect the drain plug washer(s) and replace if damaged or compressed.
   Torque spec

   Block Drain Plug25 Nm (18 lb-ft)
4. 4

   Drain coolant reservoir
   Locate the pressurized coolant expansion tank in the engine bay per the factory service manual. Disconnect the lower hose from the reservoir by loosening the hose clamp and sliding it back, then pulling the hose free. Allow remaining coolant to drain into your drain pan. Remove reservoir cap to aid drainage if needed.
   Torque spec

   Coolant Hose Clamps4 Nm (3 lb-ft)
5. 5

   Perform flush cycle (optional but recommended)
   If performing a complete flush, close the radiator petcock and reinstall block drain plugs finger-tight. Fill the system with distilled water through the radiator opening. Start the engine and allow it to reach operating temperature (thermostat open, approximately 195°F). Run for 5 minutes, then shut off and allow to cool completely. Repeat drain procedure from steps 2-3. This step removes remaining old coolant and contaminants.
6. 6

   Reinstall drain components
   Install new washer(s) on the engine block drain plug(s). Thread drain plug(s) in by hand first to prevent cross-threading, then torque to the factory specification. Close the radiator drain petcock by rotating clockwise until hand-tight only — do not apply wrench torque to the plastic petcock.
   Torque spec

   Block Drain Plug25 Nm (18 lb-ft)

   Drain Petcock5 Nm (4 lb-ft)
7. 7

   Reconnect reservoir hose
   Reconnect the lower hose to the coolant overflow reservoir. Position the hose clamp over the hose barb and tighten to specification. Ensure hose is fully seated on the reservoir neck.
   Torque spec

   Coolant Hose Clamps4 Nm (3 lb-ft)
8. 8

   Locate and open bleed screw
   If equipped, locate the cooling system bleed screw per the factory service manual for the 8.3L V10. Using an appropriate wrench, open the bleed screw 1-2 turns to allow air to escape during the fill process. If the system uses a self-bleeding degas tank rather than a bleed screw, follow the FSM fill/bleed procedure instead.
   Torque spec

   Bleed Screw7 Nm (5 lb-ft)
9. 9

   Fill cooling system with new coolant
   Using a funnel, slowly pour Zerex G-05 HOAT 50/50 pre-mixed coolant into the coolant expansion tank filler opening. Fill slowly to allow air to escape through the open bleed screw. Continue filling until coolant flows steadily from the bleed screw with no air bubbles, then close the bleed screw to specification. Continue filling the radiator to the base of the filler neck.
   Torque spec

   Bleed Screw7 Nm (5 lb-ft)
10. 10

    Fill coolant reservoir
    Add coolant to the overflow reservoir to the COLD FILL line marked on the side of the tank. Do not overfill. Install the reservoir cap securely.
11. 11

    Initial burping cycle
    With the radiator cap still off, start the engine and allow it to idle. Monitor coolant level in the radiator and add coolant as needed as air pockets work their way out. Gently squeeze accessible upper radiator hoses to help release trapped air. Continue this process until coolant level stabilizes and no more air bubbles emerge.
12. 12

    Heat cycle and final bleed
    Continue running the engine until it reaches full operating temperature and the electric cooling fans cycle on. This confirms the thermostat has opened. Monitor for steady coolant circulation visible in the radiator. Once fans cycle, shut off engine and allow to cool for 10-15 minutes. Check coolant level and top off as needed. Install radiator cap securely.
13. 13

    Test drive and recheck
    Test drive vehicle for 10-15 minutes, reaching normal operating temperature. Return to workspace and allow engine to cool until radiator is warm but safe to touch. Check radiator coolant level by carefully removing cap - add coolant if level has dropped. Check reservoir level and adjust to COLD line if necessary.

Reassembly

1. Reinstall engine cover by aligning clips and pressing down until all corners click into place.
2. Inspect ground area for any coolant spills and clean thoroughly.
3. Dispose of old coolant at an approved recycling center - do not pour down drains.

Verification

• Start engine and verify coolant temperature gauge reads normal operating range (approximately 195°F) within 5-10 minutes.
• Verify electric cooling fans cycle on and off automatically as designed.
• With engine at operating temperature, check for coolant leaks around drain plugs, hoses, and reservoir connections.
• Check coolant overflow reservoir level - should be at HOT FILL line when engine is at operating temperature.
• If available, use a coolant hydrometer or refractometer to verify proper 50/50 mixture concentration (freeze protection to approximately -34°F).
• Monitor coolant level over the next few days of driving and top off as needed as any remaining air works out of the system.

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