Fluid Leak Diagnosis

Systematic diagnosis of fluid leaks on the Rivian EDV 500, including inspection of EV transmission fluid, coolant systems, brake fluid, differential oils, and washer fluid to identify leak source and severity.

Warnings

Tools required

Parts

• Replacement fluid (as determined by diagnosis) × 1 — Varies by leak location

Fluids

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

Preparation

1. Verify customer complaint and review service history for previous leak repairs or fluid additions
2. Place vehicle on level surface and engage parking brake
3. Place vehicle in service/transport mode per Rivian service manual procedures
4. Allow all systems to cool completely (minimum 2 hours after operation)
5. Install protective fender covers to prevent damage during inspection
6. Gather all necessary tools and place drain pans strategically under vehicle
7. Perform initial visual inspection from above to identify obvious leak traces
8. Check fluid level warnings on instrument cluster and note any active fault codes

Procedure

1. 1

   Initial underbody inspection
   Safely raise vehicle on lift or jack stands ensuring proper load distribution. Perform systematic visual inspection of entire underbody from front to rear. Look for wet spots, fluid trails, drip patterns, and accumulated debris that may indicate leak paths. Note the color and consistency of any fluids found: coolant is typically pink/orange, transmission fluid is red/pink, differential oil is amber/brown, brake fluid is clear/amber, washer fluid is blue/green.
2. 2

   Clean suspected leak areas
   Using brake cleaner and clean rags, thoroughly clean all suspected leak areas to remove old fluid, dirt, and road grime. This establishes a clean baseline for leak detection. Pay special attention to areas where components overlap or where fluid could travel along seams. Allow cleaner to evaporate completely before proceeding.
3. 3

   Inspect EV transmission system
   Examine the dual motor transmission housings on both front and rear axles. Inspect all seals, gasket surfaces, fill/drain plugs, breather vents, and halfshaft seals. Check for pink/red fluid indicating EV transmission fluid leak. Inspect mounting points and housing for cracks. Use inspection camera if access is limited. Note that EDV 500 uses approximately 10 quarts total transmission fluid.
4. 4

   Inspect battery and motor coolant system
   Visually inspect coolant hoses, connections, heat exchanger, battery thermal management system lines, and motor cooling passages. Look for pink/orange coolant residue or crystalline deposits indicating evaporated coolant. Check all hose clamps for tightness and hoses for cracks or bulging. Inspect the chiller unit and coolant reservoir for leaks. DO NOT open or disconnect any coolant system components without proper high voltage safety procedures.
5. 5

   Inspect brake hydraulic system
   Check brake master cylinder reservoir cap and body for leaks. Trace brake lines from master cylinder to each wheel, inspecting for wet spots or fluid trails. Examine each brake caliper for leaks around piston seals and bleeder screws. Check brake fluid level in reservoir and test condition with test strips if available. Clear/amber fluid that appears wet indicates possible brake fluid leak.
6. 6

   Inspect front differential
   Examine front differential housing, fill/drain plugs, and breather assembly. Check front differential output seals where halfshafts exit the housing. Look for amber/brown gear oil residue. Front differential holds approximately 1.5 quarts of 75W-90 GL-5 gear oil. Inspect for impact damage to differential housing that could cause leaks.
7. 7

   Inspect rear differential
   Examine rear differential housing, cover gasket, fill/drain plugs, pinion seal, and output seals. Check for gear oil leaks indicated by amber/brown fluid. Rear differential holds approximately 2.0 quarts of 75W-90 GL-5 gear oil. Inspect driveline connections and mounting points for seal damage or housing cracks.
8. 8

   Inspect transfer case (if equipped)
   Locate and inspect transfer case assembly. Check case housing, seals, fill/drain plugs, and input/output shaft seals for leaks. Transfer case holds approximately 2.5 quarts of transfer case fluid. Verify no cross-contamination between transfer case and adjacent components.
9. 9

   Inspect washer fluid system
   Check windshield washer reservoir, pump connections, supply lines to front and rear nozzles, and all hose connections. Blue/green fluid indicates washer fluid leak. System holds approximately 3.5 quarts. Check for freeze damage if vehicle operated in cold climate. This is the least critical leak but should be documented.
10. 10

    Apply UV dye if leak not found
    If visual inspection does not reveal leak source, add appropriate UV dye to suspected system(s). Add coolant dye to coolant reservoir, transmission dye to transmission(s), or differential dye to differentials as appropriate. Follow dye manufacturer instructions for quantity. Document which systems received dye and dye type used.
11. 11

    Test drive and recheck
    If UV dye was applied, drive vehicle for 15-20 miles including highway and city driving to circulate fluids and allow leak to manifest. Return vehicle to lift and inspect all previously cleaned areas with UV flashlight in darkened area. Fluorescent dye will clearly show leak path and source. Document findings with photos showing UV dye trace.
12. 12

    Verify fluid levels
    Check fluid levels in all suspected systems. For transmission, use fill plug check method per service manual. Check coolant level in reservoir when cold. Verify brake fluid at MAX line. Check differential levels at fill plug. Low fluid level confirms active leak and indicates severity. Document all fluid levels.
13. 13

    Check for fault codes
    Connect diagnostic scan tool and check for fluid-related fault codes including coolant temperature sensor faults, low fluid level warnings, brake fluid level sensor codes, or transmission temperature warnings. Document all codes as they may indicate internal leaks or system failures not visible externally.
14. 14

    Document findings and classify leak severity
    Create detailed documentation including photos of leak location, fluid type identified, estimated leak rate (seep/drip/stream), affected components, and fluid levels. Classify as: Class 1 (seepage with no drips), Class 2 (drips but not steady stream), Class 3 (steady stream or significant fluid loss). Provide repair recommendations and parts needed based on findings.

Reassembly

1. Lower vehicle from lift safely
2. Remove protective fender covers
3. Clean any brake cleaner residue from painted surfaces
4. Reset service mode and return vehicle to normal operation if no repairs being performed immediately

Verification

• Review all documentation and photos to confirm leak source is positively identified
• Verify fluid levels are safe for customer to drive vehicle if repair is delayed
• Confirm no tools or rags left under vehicle
• Provide customer with clear explanation of leak location, severity, and repair recommendations
• If UV dye was used, inform customer that dye remains in system and will aid future diagnosis
• Schedule follow-up repair appointment with parts availability confirmed

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