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Mercedes-Benz Diesel Engine - Coolant Loss From Inlet Manifold Area.

Technical Article
POSTED 14 August 2022

Mercedes-Benz Diesel Engine - Coolant Loss From Inlet Manifold Area.

Affected Vehicles

Mercedes Benz

W204, W212, W172, W906, W639, W166 in common, various other models with OM651 fitted OM651 2009 -2016



  1. Coolant loss from inlet manifold area

Possible Causes


  1. Connection outlet incorporating fuel filter housing warps due to heat soak. New modified housing kit available.

Repair Steps

  1. Drain cooling system.
  2. Remove EGR cooler to gain correct access to housing. Do not open the fuel system if possible, as there are known instances of air locks after repair which prevents start-up. If the fuel filter is removed/replaced, make sure to carry out fuel system activation of low-pressure pump before attempting to crank the engine.
  3. Remove old housing
  4. Always ensure cleanliness when doing repair
  5. Replace fuel filter housing. Tighten the bolt in sequence:
    1. Tighten the two bolts for the two-hole flange on the cylinder head, first to 10Nm
    2. Tighten the three bolts for mounting on to the inlet manifold 8.5Nm
Parts Required - EPC part number location (Check according to VIN for correct part number)


  • A651 200 39 00 Repair kit.
  • A651 142 24 80 Metal gasket for EGR cooler.

Special tools Required:

Coolant receptacle


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