Cooling System Pressure Test

This procedure tests the integrity of the electric vehicle's cooling system for the battery pack and electric motors by pressurizing the system to identify leaks, weak points, or component failures.

Warnings

Tools required

Parts

• Coolant reservoir cap (if damaged) × 1 — Use OEM specification
• Coolant pressure relief valve (if faulty) × 1 — Use OEM specification
• Quick-connect fittings (as needed) × 1 — Use OEM specification

Fluids

• EV Battery/Motor Coolant — 1 qt

Preparation

1. Park vehicle on level surface and engage parking brake. Place wheel chocks at all four wheels
2. Allow cooling system to cool completely for minimum 2 hours after last operation
3. Verify 12V battery is fully charged and in good condition
4. Access high voltage service disconnect located in rear cargo area under access panel
5. Using service disconnect tool, remove high voltage service disconnect and wait 5 minutes for capacitor discharge
6. Verify high voltage isolation using digital multimeter between HV+ and chassis ground (should read >500V DC resistance)
7. Connect scan tool and verify no active cooling system DTCs. Document any existing codes
8. Raise vehicle on lift or jack stands if underbody access is required for inspection
9. Locate coolant reservoir in front motor compartment area
10. Check coolant level and note current level before testing

Procedure

1. 1

   Identify cooling system circuits
   Using the scan tool, navigate to the thermal management system menu. Identify whether you are testing the battery cooling circuit, motor/inverter cooling circuit, or both. The EDV 500 uses separate circuits with different operating pressures. Document the target circuit(s) for this test. Verify circuit routing using the vehicle service information to understand coolant flow path.
2. 2

   Perform initial visual inspection
   Inspect all visible coolant hoses, connections, radiator assemblies, and reservoir for obvious signs of leakage, damage, or deterioration. Pay special attention to quick-connect fittings at motor and battery pack interfaces, heat exchanger connections at the chiller unit, and electric coolant pump housings. Check for coolant staining, crusty deposits, or swelling of rubber components. Inspect underbody thermal management skid plate for evidence of leaks.
3. 3

   Remove coolant reservoir cap
   Slowly rotate the coolant reservoir cap counterclockwise to the first detent and allow any residual pressure to escape completely. Wait 30 seconds, then continue rotating to fully remove the cap. Inspect cap gasket for wear, cracking, or deformation. Inspect pressure relief valve in cap for proper operation and sealing surface condition. Set cap aside on clean surface.
4. 4

   Install pressure tester adapter
   Select the appropriate adapter from the EV cooling system pressure tester kit that matches the Rivian coolant reservoir neck profile. Install the adapter onto the reservoir neck, ensuring a complete seal. Thread or lock the adapter according to manufacturer instructions. Verify the adapter is secure and seated properly before proceeding.
5. 5

   Attach pressure tester
   Connect the cooling system pressure tester to the installed adapter. Ensure all connections are tight and leak-free. Verify the pressure gauge reads zero before pumping. If testing both circuits, note that you may need to pressurize each circuit separately depending on system design and isolation valve positions.
6. 6

   Pressurize the cooling system
   Slowly pump the pressure tester to bring the system to the specified test pressure of 15-18 PSI (do not exceed 20 PSI). Monitor the gauge carefully during pressurization. Stop immediately if pressure rises rapidly or abnormally, which may indicate a blocked system. Once target pressure is reached, stop pumping and observe the initial gauge reading.
7. 7

   Monitor pressure stability
   Observe the pressure gauge for 2 minutes without touching the vehicle. The system should hold pressure with no more than 2 PSI drop. Document the starting pressure, ending pressure, and time elapsed. A pressure drop exceeding 2 PSI indicates a leak that must be located. If pressure holds steady, proceed to detailed inspection while maintaining pressure.
8. 8

   Inspect external components under pressure
   With the system pressurized, perform a thorough visual and physical inspection of all accessible cooling system components. Check all hose connections, clamps, reservoir seams, radiator end tanks, heat exchanger connections, coolant pump housing seals, and quick-connect fittings. Look for coolant weeping, misting, or dripping. Use a clean paper towel to wipe suspect areas and check for wetness. Pay particular attention to motor coolant jacket connections and battery pack thermal interface points.
9. 9

   Inspect underbody and internal components
   If vehicle is raised, inspect all underbody cooling system components including the battery pack thermal plate connections, underbody coolant lines, heat exchanger assemblies, and chiller unit connections. Use infrared thermometer to identify cold spots that may indicate internal blockages if pressure test shows anomalies. Check the cabin HVAC heat exchanger area for coolant odor or visible leaks at firewall penetrations.
10. 10

    Perform UV dye test if needed
    If pressure loss is detected but no visible leak is found, release pressure from the system and add the appropriate amount of UV leak detection dye compatible with EV coolant. Re-pressurize the system to 15 PSI and allow to sit for 5 minutes. Use UV light to inspect all cooling system components, particularly in hard-to-see areas like the back of the electric motor housings and battery pack interfaces. UV dye will fluoresce brightly at leak points.
11. 11

    Test pressure relief valve operation
    With system at test pressure, verify that the reservoir cap pressure relief valve opens at the correct pressure (typically 18-22 PSI depending on circuit design). Carefully increase pressure while watching gauge. The relief valve should open before reaching maximum safe pressure. If testing reveals relief valve malfunction, replace the reservoir cap.
12. 12

    Release system pressure
    Slowly release all pressure from the cooling system using the pressure tester release valve. Allow pressure to drop gradually to zero over 30-60 seconds to prevent coolant surge. Once pressure is fully released, disconnect the pressure tester from the adapter and remove the adapter from the reservoir neck.
13. 13

    Document findings and repair
    Document all test results including starting pressure, ending pressure, pressure drop rate, and location of any identified leaks. Photograph any damaged components. If leaks were found, repair or replace affected components according to Rivian service procedures. Common leak points include quick-connect O-rings, coolant pump seals, and heat exchanger connections. After repairs, retest the system to verify leak is corrected.
14. 14

    Check and adjust coolant level
    With system depressurized and cool, check coolant level in reservoir. Add EV Battery/Motor Coolant as needed to bring level to the COLD FILL mark. Use only the specified EV coolant to maintain proper electrical conductivity and corrosion protection. Do not mix coolant types. If significant coolant was lost during testing or repair, the system will need proper bleeding procedure.
15. 15

    Reinstall reservoir cap and restore vehicle
    Install the coolant reservoir cap, ensuring it is properly seated and tightened. Reinstall the high voltage service disconnect in the rear cargo area. Clear any diagnostic codes related to HV disconnect using scan tool. Lower vehicle if raised. Verify all tools and equipment are removed from vehicle.

Reassembly

1. Ensure coolant reservoir cap is properly installed and tightened
2. Verify high voltage service disconnect is reinstalled and lockout/tagout removed
3. Confirm all cooling system components are properly secured and connected
4. Remove wheel chocks and lower vehicle to ground if raised

Verification

• Start the vehicle and allow thermal management system to initialize. Monitor scan tool for proper coolant circulation and temperature readings in both battery and motor circuits
• Verify no new cooling system DTCs are present using scan tool
• Allow vehicle to run through a complete thermal management cycle (approximately 15-20 minutes) and recheck coolant level when system is warm
• Perform a final visual inspection for any coolant leaks around tested components
• Test drive vehicle and monitor coolant temperature stability using instrument cluster or scan tool. Battery and motor temperatures should remain within normal operating range
• Recheck coolant level after test drive when system has cooled to ambient temperature. Top off if necessary to COLD FILL mark

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