LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Ford >> 2021 >> Explorer ST >> Repair and Diagnosis >> Engine Mechanical >> Mechanical >> Engine System - General Information >> Diagnosis And Testing >> Engine >> Component Tests
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Component Tests

The following component tests are used to diagnose engine concerns.

Engine Oil Leaks 

NOTE: If an overnight drive is done, the fan air or road air blast can cause erroneous readings.
NOTE: When diagnosing engine oil leaks, the source and location of the leak must be positively identified prior to repair.

Prior to carrying out this procedure, clean the cylinder block, cylinder heads, valve covers, oil pan and flywheel/flexplate with a suitable solvent to remove all traces of oil.

Hybrid Engine Running Diagnostic Mode 

To get the hybrid engine to go into the Engine Running diagnostic mode, specific sequences of pedal events have to be executed within a specific time interval. The activation sequence is as follows:

  1. Ensure that the vehicle is in Park gear.
  2. Turn the ignition to Key On Engine Off.
  3. Within 5 seconds fully depress the brake pedal and accelerator pedal together for 10 seconds.
  4. With the brake fully depressed within 5 seconds release the accelerator and toggle the ignition to RUN or START for vehicles with key start.
  5. NOTE: The engine will start and run at the park rev limiter (4, 000 RPM).

    Fully depress the accelerator pedal and hold for 10 seconds.

  6. When the READY indicator turns off, release the accelerator.
  7. NOTE: If the vehicle has successfully entered the Engine Running Diagnostic Mode the indicator will flash once every 3 seconds.

    If the indicator does not shut off after 10 seconds, turn the ignition off to abort the procedure. Let the vehicle sit for several minutes to allow all modules to power down. Repeat the procedure.

Engine Oil Leaks - Fluorescent Oil Additive Method 

NOTE: If the factory fill engine oil with dye is present, change the engine oil and the oil filter prior to using the Dye-Lite® Oil-Based Fluid Dye (164-TP33200601).
NOTE: Oil leaks form drops of oil and while seepage does not. Oil seepage is considered normal.

Use the UV Long-Wave W/12-foot Cord and Alligator Clips (164-R3748) or Leak Tracker UV-LED Leak Detection Flashlight (164-TP8695) to carry out the following procedure for oil leak diagnosis.

  1. Add 29.6 ml (1 oz) of Dye-Lite® Oil-Based Fluid Dye (164-TP33200601) to a minimum of 0.47L (1/2 qt) and a maximum of 0.95L (1 qt) engine oil. Thoroughly premix the oil based fluid dye or it will not have enough time to reach the crankcase, oil galleries and seal surfaces during this particular 15 minute test. The additive must be added through the oil fill. Check the level on the oil level indicator to determine what amount of oil to premix. If it is in the middle of the crosshatch area or below the full mark, use 0.95L (1 qt). If it is at the full mark, use 0.47L (1/2 qt).
  2. NOTE: For best results allow the customer to drive the vehicle for a day.

    Run the engine for 15 minutes. Stop the engine and inspect all seal and gasket areas for leaks using the UV Leak Detector Kit. A fluoresces white area will identify the leak. For extremely small leaks, several hours may be required for the leak to appear.

  3. At the end of test, make sure the oil level is within the upper and lower oil indicator marks. Remove oil as necessary if it registers above the full mark.

Leakage Points - Underhood 

Examine the following areas for oil leakage:

Leakage Points - Under Engine, With Vehicle on Hoist 

Examine the following areas for oil leakage:

Leakage Points - With Transmission and Flywheel/Flexplate Removed 

NOTE: FHEV engines are equipped with DMF (Dual Mass Flywheel).

Examine the following areas for oil leakage:

scientia non olet · About LEMON Manuals