This procedure systematically identifies the source and type of fluid leaks on a 2021-2024 Ford F-150 with 3.5L EcoBoost V6 engine using visual inspection, UV dye if necessary, and fluid identification techniques.

Warnings

Tools required

Parts

• Shop towels or absorbent pads × 1 — Use clean, lint-free towels

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow engine and all fluids to cool completely (minimum 30 minutes)
3. Place absorbent cardboard or paper under vehicle overnight to identify active leak locations
4. Check cardboard for fluid spots and note color, location, and approximate drip rate
5. If available, review service history for recent fluid services or component replacements

Procedure

1. 1

   Perform initial visual inspection from above
   Open hood and visually inspect engine bay with work light. Check engine oil filler cap and dipstick tube for wetness. Inspect valve covers along their perimeter for oil seepage (common on EcoBoost engines). Check coolant reservoir level and inspect reservoir and cap for cracks. Examine power steering reservoir area (electric system, but check mounting area for other fluid contamination). Inspect brake master cylinder reservoir and area around ABS unit. Look for any obvious drips or fluid accumulation on engine cover and intake components.
2. 2

   Raise and secure vehicle
   Raise vehicle using floor jack at designated front jacking point. Support with jack stands under frame rails rated for vehicle weight. Ensure vehicle is stable before working underneath. Remove front skid plate if equipped by removing fasteners to access engine underside.
3. 3

   Inspect engine oil system from below
   Using work light, inspect oil pan for damage, corrosion, or seepage along pan rail. Check oil drain plug for wetness or drips. Inspect oil filter housing and oil filter for leaks (EcoBoost filter is accessed from below on RWD models). Check oil cooler lines where they connect to engine block and oil cooler assembly. Look for oil accumulation on front differential (RWD) which may indicate engine leak dripping down. Examine lower turbocharger oil drain tubes and connections for seepage.
   Torque spec

   Oil Drain Plug35 Nm (26 lb-ft)
4. 4

   Inspect coolant system components
   Check radiator lower hose connections and clamps for leaks. Inspect water pump weep hole (located on lower front of engine) for coolant seepage, which indicates pump seal failure. Examine thermostat housing on front of engine for leaks. Check engine block freeze plugs for corrosion or seepage. Inspect heater hose connections at firewall. Look for coolant residue on AC compressor and alternator (indicates leak dripping from above). Check intercooler and charge air cooler hoses and connections for coolant or condensation (these can leak coolant on EcoBoost models).
5. 5

   Inspect transmission and transfer case (if equipped)
   Locate transmission pan and inspect pan rail, drain plug area, and transmission cooler line connections for ATF leaks. Check transmission output shaft seal area at transmission tail housing. On 4WD models, inspect transfer case for fluid seepage. Check electrical connector seals on transmission solenoid body (visible on driver side of transmission). Look for red/pink ATF on crossmember and transmission mount.
6. 6

   Inspect rear differential and driveline
   Inspect rear differential cover for gear oil leaks along gasket surface. Check differential pinion seal at driveshaft connection point for oil seepage. Examine axle tube seals at each wheel hub. Inspect driveshaft center support bearing for grease leakage. Look for dark brown/amber gear oil accumulation on differential housing or rear suspension components.
7. 7

   Identify fluid type by characteristics
   Collect small sample of leaked fluid on clean white rag or paper towel. Identify fluid by color and feel: Engine oil (amber to dark brown, slippery), Coolant (orange/pink, sweet smell, watery), ATF (bright red to dark red, slippery, petroleum smell), Gear oil (amber to brown, very thick, strong sulfur smell), Brake fluid (clear to amber, very slippery, absorbs into rag), Washer fluid (blue or green, watery, alcohol smell), Condensation from AC (clear water, no smell). Note the location directly above where fluid was found to trace source.
8. 8

   Clean leak area for monitoring
   If leak source is not immediately obvious, spray suspected area with degreaser and wipe clean with shop towels. This allows fresh leaking to be easily identified. For difficult-to-locate leaks, apply UV leak detection dye to the suspected fluid system following dye manufacturer instructions (add to engine oil, coolant, or ATF as appropriate). Clean exterior of component thoroughly after dye addition.
9. 9

   Perform operational leak check if needed
   If no leak is visible on static inspection but leak evidence exists, start engine and allow to reach operating temperature while monitoring from below. Watch for active leaking at operating temperature and pressure. For transmission leaks, shift through all gear positions while observing transmission. Check coolant system for leaks at full operating pressure. Use UV light to scan dyed systems for fluorescent leak trails. Note that some leaks only occur under specific conditions (hot, cold, pressure, or during operation).
10. 10

    Document findings
    Record leak location, fluid type, severity (seepage, drip, or stream), and affected components. Take photos of leak source and fluid accumulation areas. Note whether leak is active or residual from previous leak. Document any damaged components, loose fasteners, or deteriorated hoses. This documentation will guide repair procedure selection and parts ordering.

Reassembly

1. Reinstall front skid plate if removed, ensuring all fasteners are properly secured
2. Lower vehicle from jack stands and remove support equipment
3. Clean any spilled fluids from shop floor and dispose of contaminated rags properly

Verification

• Verify leak source has been positively identified and documented
• Confirm fluid type matches suspected system
• Check that all vehicle systems remain operational after inspection
• Review photos and notes to ensure repair procedure can be planned accurately
• If UV dye was used, document system so technician performing repair is aware dye is present

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