Analysis of Leakage

2009 Mercury Milan AWD L4-2.3LSECTION Analysis of Leakage



Power Transfer Unit (PTU)

Analysis of Leakage

The PTU may leak different color fluids, red oil leak for an automatic transmission fluid and brown/black gear lube for PTU fluid. The PTU seals prevent these types of fluids from leaking. It is important to note which color of fluid is leaking to conduct the most appropriate service procedure.

PTU Leaks From the RH Side

NOTICE: Remove and replace leaking seals using the information found in the Intermediate Shaft Seal and Deflector Intermediate Shaft Seal and Deflector or Cover Seal Cover Seal replacement procedure. The specified tools called out in this procedure will allow seal replacement without causing damage to the Power Transfer Unit (PTU) casing/drive gear.

If the leak is red automatic transmission fluid, this indicates the differential seals in the transaxle are also leaking and need to be replaced along with the intermediate shaft seal. Refer to the Intermediate Shaft Seal and Deflector Intermediate Shaft Seal and Deflector procedure to replace the intermediate seal.

If the leak is brown/black gear lube, then the PTU larger cover seal needs replacement. This is located on the PTU cover behind the deflector. Refer to Cover Seal Cover Seal procedure.










PTU Leaks From the LH Side

If the leak is the red automatic transmission fluid, the compression seal needs replacement. This is between the PTU and transmission. Refer to Power Transfer Unit (PTU) Transfer Case - Power Transfer Unit (PTU) - Removal in the Removal portion.

If the leak is brown/black, the PTU is overfilled and venting fluid from the top of the PTU. Flush and fill the PTU. Refer to Power Transfer Unit (PTU) Draining and Filling Procedures.










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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.