Fluid Leak Diagnosis

Systematic diagnosis of fluid leaks on the Rivian EDV 500 electric delivery van, including inspection of EV transmission fluid, battery/motor coolant, brake fluid, differential gear oil, transfer case fluid, and windshield washer fluid systems.

Warnings

Tools required

Parts

• Replacement fluid as identified × 1 — Use OEM specification

Fluids

• EV Transmission Fluid
• EV Battery/Motor Coolant
• DOT 4 Brake Fluid
• 75W-90 GL-5 Gear Oil
• Transfer Case Fluid

Preparation

1. Park vehicle on level surface and engage parking brake
2. Place cardboard or clean paper under vehicle overnight if possible to capture drip pattern and location
3. Document any visible stains, drip locations, and fluid colors with photos
4. Check fluid levels in all reservoirs and document baseline levels
5. Ensure vehicle has cooled completely if recently driven (minimum 2 hours)
6. Verify high voltage system is in safe mode (vehicle off, key removed)
7. Raise vehicle on lift to full working height or securely support on jack stands
8. Remove plastic belly pans and skid plates for full underbody access

Procedure

1. 1

   Initial visual inspection and fluid identification
   Perform thorough visual inspection of entire underbody. Identify fluid type by color and texture: EV coolant is typically pink/orange, gear oil is amber/brown and thick, brake fluid is clear/amber and thin, washer fluid is typically blue, and EV transmission fluid is pink/red. Note the location of any wet spots, drips, or staining. Take photos for reference.
2. 2

   Inspect battery pack thermal management system
   Inspect the battery pack perimeter for coolant leaks from the thermal management system. Check coolant hoses, connections, and heat exchanger mounting points on the underside of the battery pack. Look for pink/orange coolant residue or staining. Do not attempt to open or remove battery pack covers. Check the coolant reservoir level in the frunk area and compare to documented baseline.
3. 3

   Inspect motor cooling systems
   Examine both front and rear drive units (motors) for coolant leaks. Inspect cooling lines running to each motor assembly, connection points at the motor housings, and the integrated motor cooling circuits. Check for wet spots or coolant residue around motor mounting areas. Verify coolant level has not dropped from baseline.
4. 4

   Inspect EV transmission/drive unit seals
   Inspect both front and rear drive units for EV transmission fluid leaks. Check output shaft seals, housing mating surfaces, and drain/fill plug areas. Look for pink/red fluid residue. Clean any accumulated dirt from suspected areas with brake cleaner to identify active vs. old leaks. Check transmission fluid level if dipstick or fill plug is accessible.
5. 5

   Inspect differential assemblies
   Examine the front differential (1.5 qt capacity) and rear differential (2.0 qt capacity) for gear oil leaks. Check pinion seals, axle seals, cover gaskets, fill plugs, and drain plugs. Look for amber/brown oil residue or wet spots. Note that some seepage from breather vents may be normal, but active dripping indicates seal failure.
6. 6

   Inspect transfer case
   Locate and inspect the transfer case assembly (2.5 qt capacity) for fluid leaks. Check all seals, mating surfaces, shift actuator mounting points if equipped, and fill/drain plugs. Look for amber fluid residue. Clean suspected areas and check for active leaking.
7. 7

   Inspect brake hydraulic system
   Inspect all four brake calipers for brake fluid leaks at piston seals and bleeder screws. Check brake lines and fittings along frame rails and at each wheel. Inspect the brake master cylinder in the engine bay for leaks at the reservoir, pushrod seal, and output ports. Check the ABS/ESC module for leaks at brake line connections. Verify brake fluid reservoir level against baseline.
8. 8

   Inspect windshield washer system
   Check the windshield washer fluid reservoir (3.5 qt capacity) for cracks or leaks. Inspect the washer pump connections and all washer fluid lines running to the windshield and rear windows. Check spray nozzles for leaks. Blue fluid staining typically indicates washer fluid. Verify reservoir fluid level.
9. 9

   Clean and apply UV dye if needed
   If leak source cannot be visually identified, thoroughly clean all suspected areas with brake cleaner and allow to dry. Add appropriate UV dye to the suspected fluid system (coolant, gear oil, or brake fluid). Add coolant dye to coolant reservoir, gear oil dye through differential fill plugs, etc. Follow dye manufacturer instructions for concentration and compatibility with EV fluids.
10. 10

    Operate vehicle and recheck
    If UV dye was applied, lower vehicle and operate according to dye manufacturer instructions (typically drive for 10-20 minutes or until system reaches operating temperature). Re-raise vehicle and inspect all previously suspect areas with UV flashlight. Active leaks will show bright fluorescent trails leading from the source. Document leak source location with photos.
11. 11

    Perform pressure testing if applicable
    For suspected coolant leaks that are difficult to locate, connect a cooling system pressure tester to the coolant reservoir. Pressurize system to specified pressure (typically 15-20 psi, verify in service manual). Inspect all cooling system components while under pressure. Leaks will become more apparent under pressure. Release pressure before disconnecting tester.
12. 12

    Check for internal leaks
    If external leak source cannot be found but fluid loss is confirmed, check for internal leaks. For coolant, inspect interior HVAC case drains for coolant presence indicating heater core leak. Check for coolant contamination in EV transmission fluid or vice versa indicating heat exchanger failure. Inspect cargo area for hidden leaks behind panels.
13. 13

    Document findings and recommend repairs
    Document all identified leak sources with photos, locations, and severity assessment. Note fluid types and estimated loss rates. Create repair recommendation list prioritizing by severity: active leaks requiring immediate repair, seepage requiring monitoring, and staining from previous resolved leaks. Provide fluid quantity estimates needed for top-off or system refill after repairs.

Reassembly

1. Clean all inspected areas to remove brake cleaner residue
2. Reinstall all belly pans and skid plates removed for access
3. Top off any fluid reservoirs that were depleted during diagnosis to proper levels
4. Remove UV dye containers and pressure test equipment
5. Lower vehicle from lift or remove from jack stands
6. Remove cardboard or paper from under vehicle

Verification

• Verify all fluid reservoirs are at proper levels after diagnosis
• Confirm all access panels and skid plates are properly reinstalled
• Review all documentation and photos to ensure leak sources are clearly identified
• Start vehicle and verify no warning lights related to fluid levels appear on dashboard
• If UV dye was used, inform customer that fluorescent dye will remain in system and may be visible during future service
• Provide customer with detailed report of findings including photos, leak locations, recommended repairs, and priority level for each identified leak

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