Cooling System Pressure Test

Perform a pressure test on the EV cooling system to identify leaks in the battery thermal management system, motor cooling circuits, and associated components.

Warnings

Tools required

Parts

• Cooling system pressure tester adapter (Rivian-specific or universal EV) × 1 — Use OEM specification
• Coolant reservoir cap (if damaged) × 1 — Use OEM specification
• O-rings and seals (service kit) × 1 — Use OEM specification

Fluids

• EV Battery/Motor Coolant — 10 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Ensure vehicle has been off for minimum 2 hours and cooling system is at ambient temperature
3. Disconnect 12V auxiliary battery using Rivian service mode procedure
4. Place High Voltage Disconnect switch in service position following manufacturer lockout/tagout protocol
5. Verify HV system is de-energized using digital multimeter at designated test points
6. Remove front underbody shield to access cooling system drain points
7. Place large drain pan under vehicle front center section
8. Connect Rivian diagnostic tool and document any existing cooling system fault codes

Procedure

1. 1

   Access coolant reservoir and expansion tank
   Remove front trunk (frunk) liner panels using trim removal tools. Locate the coolant reservoir and expansion tank assembly on driver side of frunk compartment. Inspect reservoir for correct fill level and visual contamination or debris in coolant.
2. 2

   Verify cooling system temperature
   Use infrared thermometer to verify coolant temperature at reservoir neck and radiator hoses is below 100°F (38°C). Do not proceed if system temperature exceeds this value. Check for residual system pressure by carefully loosening reservoir cap 1/4 turn and listening for pressure release.
3. 3

   Drain coolant to appropriate level
   Partially drain cooling system by opening drain valve located at bottom of front thermal management radiator. Drain approximately 2 quarts of coolant to allow room for system expansion during pressure testing. Close drain valve securely and verify no leakage. Retain drained coolant for inspection and potential reuse if uncontaminated.
4. 4

   Install pressure tester adapter
   Remove coolant reservoir cap completely. Select appropriate adapter from pressure tester kit that fits Rivian reservoir neck (typically uses large diameter EV-specific adapter). Install adapter onto reservoir neck ensuring proper seal with O-ring. Thread pressure tester pump onto adapter and verify secure connection.
5. 5

   Perform initial visual inspection
   Before pressurizing system, conduct thorough visual inspection of all accessible cooling system components including hoses, clamps, radiator, battery cooling plate connections, motor cooling lines, and heater core connections. Look for existing coolant residue, stains, or obvious damage that indicates leak location.
6. 6

   Pressurize battery cooling circuit
   Slowly pump pressure tester to 15 PSI while monitoring gauge. Do not exceed 15 PSI for battery cooling circuit. Observe pressure gauge for 2 minutes - pressure should remain stable. A drop of more than 2 PSI in 2 minutes indicates a leak. If pressure holds, increase to 18 PSI for secondary test and hold for additional 3 minutes.
7. 7

   Inspect battery thermal management connections
   With system pressurized, inspect all battery pack cooling connections at pack entry/exit points, coolant distribution manifold under vehicle, and battery cooling plate interfaces. Look for coolant seepage, wetness, or pressure-induced leaks. Pay special attention to quick-disconnect fittings and compression joints.
8. 8

   Inspect motor and inverter cooling lines
   Trace cooling lines from battery circuit to front and rear motor assemblies. Inspect all connections at motor cooling jackets, inverter cooling plates, and associated hoses. Check flexible hose sections for bulging or weeping under pressure. Inspect aluminum hard lines for corrosion or impact damage.
9. 9

   Check cabin heating system integration
   Inspect connections where EV cooling system interfaces with cabin HVAC heat exchanger. Check heater core inlet/outlet connections in HVAC box area and coolant control valves. Look for leaks at electric coolant pump connections and associated wiring seals.
10. 10

    Test radiator and heat exchanger assembly
    Inspect front-mounted radiator assembly for leaks at core, side tanks, and mounting brackets. Check for coolant seepage at radiator-to-condenser interfaces and transmission cooler integration points. Verify cooling fan motor seals show no coolant intrusion.
11. 11

    Document and mark leak locations
    If leaks are identified, mark locations with grease pencil or tape flags. Document leak locations with photos and notes in diagnostic tool. If UV dye was added to coolant, use UV light to identify small seepage points not visible under normal lighting. Record pressure loss rate if applicable.
12. 12

    Release system pressure
    Slowly release pressure from tester using pressure release valve. Allow system to fully depressurize before removing tester adapter. Remove adapter and inspect O-ring for damage or wear. Reinstall original coolant reservoir cap.
13. 13

    Refill and bleed cooling system
    If coolant was drained, refill system with EV Battery/Motor Coolant to proper level as indicated on reservoir. Total system capacity is 10 quarts. Use Rivian diagnostic tool to activate cooling system purge procedure to remove air pockets from battery cooling circuit. Run purge cycle for specified duration (typically 10-15 minutes).
14. 14

    Verify system operation
    With 12V battery reconnected but HV system still disabled, use diagnostic tool to command coolant pumps to run. Verify both battery circuit pump and motor circuit pump operate normally. Check for smooth flow and absence of cavitation noise. Verify coolant level remains stable during pump operation.

Reassembly

1. Reinstall front underbody shield and verify all fasteners are secure
2. Reinstall frunk liner panels and trim pieces ensuring proper clip engagement
3. Verify coolant reservoir cap is properly tightened and sealed
4. Clean any coolant residue from components, especially around HV connections, using distilled water and lint-free cloths
5. Reconnect 12V auxiliary battery and verify vehicle systems initialize normally
6. Clear service mode and restore HV system to operational status following Rivian procedures

Verification

• Use diagnostic tool to verify no cooling system fault codes are present
• Start vehicle and allow cooling system to reach normal operating temperature
• Monitor coolant temperature using diagnostic tool - should stabilize between 104-140°F depending on ambient conditions
• Verify coolant level remains stable at proper mark on reservoir after temperature stabilization
• Check that cooling fans activate appropriately based on system temperature
• Perform short test drive (5-10 minutes) and re-inspect all previously identified leak points for any seepage
• Verify battery thermal management system maintains proper temperature range during and after test drive
• Document final pressure test results and any repairs performed in vehicle service records

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