Cooling System Pressure Test

Perform a pressure test on the electric vehicle cooling system to identify leaks in the battery and motor thermal management circuits.

Warnings

Tools required

Parts

• Coolant reservoir cap o-ring × 1 — Use OEM specification
• Pressure test adapter for Rivian cooling system × 1 — Use OEM specification

Fluids

• EV Battery/Motor Coolant — 1 qt

Preparation

1. Park vehicle on level surface and apply parking brake
2. Ensure vehicle has been off and cooling for minimum 2 hours
3. Verify 12V battery is fully charged (low voltage systems will be active during procedure)
4. Connect diagnostic tool and verify no active cooling system fault codes
5. Place high-voltage safety lockout: Access HV disconnect under driver seat, rotate to OFF position, and remove
6. Open hood and locate coolant reservoir on driver side of front trunk compartment
7. Document current coolant level and condition
8. Check coolant concentration with refractometer (should be 50/50 mix)
9. If using UV dye method, add appropriate amount of UV dye to coolant reservoir before testing

Procedure

1. 1

   Access cooling system pressure test port
   Remove the coolant reservoir cap by turning counterclockwise slowly to relieve any residual pressure. Inspect cap and sealing surface for damage, cracks, or degradation. Check pressure relief valve in cap for proper operation. Locate the coolant reservoir fill neck which will serve as the pressure test connection point.
2. 2

   Inspect cooling system components visually
   Before pressure testing, perform a thorough visual inspection of all accessible cooling system components. Check coolant hoses for cracks, bulges, or soft spots. Inspect clamps for tightness and corrosion. Examine the battery pack cooling plate connections under the vehicle (visible from wheel wells). Check motor cooling connections at front and rear drive units. Look for signs of previous leaks including coolant residue, staining, or crystalline deposits.
3. 3

   Install pressure test adapter
   Select the appropriate adapter from the pressure tester kit that fits the Rivian coolant reservoir neck. Thread or seal the adapter onto the reservoir opening, ensuring a complete seal. Connect the pressure tester pump to the adapter. Verify all connections are secure before proceeding.
4. 4

   Perform initial system pressurization
   Slowly pump the pressure tester to bring the system up to 15 PSI. Monitor the pressure gauge closely and do not exceed 20 PSI maximum. Observe the rate of pressure increase - resistance should be consistent. If pressure builds too quickly or slowly, there may be air pockets or existing leaks in the system. Once at 15 PSI, stop pumping and observe the gauge.
5. 5

   Monitor pressure hold test - Phase 1
   With system at 15 PSI, monitor pressure gauge for 10 minutes without adding additional pressure. The system should hold pressure within 1-2 PSI maximum drop. Record starting pressure, time, and ending pressure. A pressure drop of more than 2 PSI in 10 minutes indicates a leak. If pressure holds steady, proceed to visual inspection. If pressure drops significantly, proceed immediately to leak location steps.
6. 6

   Inspect battery cooling circuit connections
   With system under pressure, carefully inspect all battery cooling system connections. Focus on the battery pack coolant inlet and outlet connections located at the front of the battery pack (accessible from front wheel wells). Check cooling plate distribution manifolds along the sides of the battery pack. Listen for hissing sounds indicating coolant escaping. Look for coolant weeping at connection points. Use inspection mirror to view hidden areas. Check coolant temperature sensors and their sealing grommets.
7. 7

   Inspect motor cooling circuit connections
   Examine the front drive unit cooling connections located at the front motor assembly. Inspect rear drive unit cooling connections at the rear motor assembly. Check flexible coolant hoses connecting the drive units to the main cooling circuit. Inspect the motor cooling jacket inlet/outlet fittings for leaks. Verify the motor temperature sensor seals are intact. Check any quick-disconnect fittings for proper seating and seal condition.
8. 8

   Inspect cooling system radiator and lines
   Check the EV cooling radiator located in the front of the vehicle behind the front fascia. Inspect radiator core for signs of coolant seepage. Check radiator end tanks and their seams. Examine inlet and outlet hose connections to the radiator. Inspect the coolant distribution lines running along the frame rails from front to rear. Check any unions, joints, or splice points in the hard lines.
9. 9

   Check electric coolant pump and valves
   Locate the electric coolant pump assembly (typically mounted near the front of the vehicle). Inspect pump housing for cracks or coolant seepage, particularly around the pump motor seal area. Check coolant control valves for leaks at the valve body seams and actuator shaft seals. Examine any bleeder valves or air purge points for leakage. Verify pump inlet and outlet connections are dry.
10. 10

    UV leak detection inspection (if equipped)
    If UV dye was added to the system, use UV light to inspect all cooling system components in a darkened area. UV dye will fluoresce brightly at leak points even when leaks are too small to see with normal inspection. Pay special attention to areas where pressure drop was noted but no visible leak was found. Inspect all hose connections, sensor ports, and component seams. Photograph any fluorescent areas for documentation.
11. 11

    Perform extended pressure hold test
    If initial 10-minute test was successful, re-pressurize system to 15 PSI and conduct an extended 30-minute pressure hold test. Monitor gauge at 5-minute intervals and record pressure readings. Total pressure loss should not exceed 3 PSI over 30 minutes. During this test, gently manipulate coolant hoses and connections to stress potential weak points. Monitor for pressure changes when components are moved.
12. 12

    Document findings and release pressure
    Record all test results including initial pressure, time intervals, final pressure, and total pressure drop. Document any leaks found with location descriptions and photographs. Slowly release pressure from the system by opening the pressure tester relief valve. Remove the pressure tester adapter from the coolant reservoir. Do not reinstall the reservoir cap yet.
13. 13

    Verify coolant level and top off if needed
    Check coolant level in the reservoir after pressure testing. The level may have changed due to redistribution during pressure testing or loss from any identified leaks. Add EV Battery/Motor Coolant as needed to bring level to the COLD FULL mark. Use only the specified coolant type - do not mix coolant formulations. If significant coolant was lost, this confirms leak location findings.
14. 14

    Clear diagnostic codes and verify system status
    Using the diagnostic tool, clear any cooling system-related fault codes that may have been triggered during testing (typically low coolant level or pressure sensor codes). Review freeze frame data if any new codes appeared. Check cooling system component status in the vehicle control module. Verify no active warnings remain before proceeding to reassembly.

Reassembly

1. Install new o-ring on coolant reservoir cap if original shows any wear or damage
2. Reinstall coolant reservoir cap and tighten securely by hand
3. Reinstall high-voltage disconnect under driver seat and rotate to ON position
4. Close hood and ensure all panels are properly secured
5. If leaks were found and repaired, repeat entire pressure test procedure to verify repairs

Verification

• Reconnect diagnostic tool and verify no active cooling system fault codes present
• Power on vehicle to READY mode and observe coolant temperature readings on diagnostic tool
• Allow coolant pumps to cycle and verify no unusual sounds or vibrations
• Check coolant level in reservoir after pumps have cycled - should remain at COLD FULL mark
• Monitor vehicle for 24 hours after testing and recheck coolant level for any delayed leaks
• If pressure test showed leaks, verify leak locations are documented in service records with repair recommendations
• If system passed pressure test with less than 2 PSI drop in 10 minutes, cooling system integrity is confirmed

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