Engine - Caution Prior to Degreasing
TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERSREF. NO. 98/48
DATE: March 1995 (supersedes S.I. MBNA 00/40a, July 1992)
Revision: Additional information on new type of anti-corrosion coating.
SUBJECT:
ALL MODELS
ANTI-CORROSION COATING FOR ENGINE COMPARTMENT
As August 1994, all vehicles have engine compartments treated with an anti-corrosion coating which is very similar to clear coat paint.
Engine compartment cleaning
Cold water type engine compartment cleaning solvents such as Gunk(R) engine cleaner should no longer be used for engine cleaning. These solvents may cause damage to the long-term anti-corrosion protection of the coating. The anti-corrosion coating is resistant to presently approved steam cleaning systems
Those customers who typically do engine cleaning of their own should be advised of this situation. Application of anti-corrosion wax is no longer required after engine compartment cleaning. Certain exceptions apply, refer to Note below.
Note:
^ The anti-corrosion coating is not available as a spare part at this time. In vehicles produced from December 1989 up to July 1994, the engine compartments must be treated with anti-corrosion wax after cleaning.
^ Upon replacing major components in the engine compartment, they must be treated with anti-corrosion wax after installation.
CAUTION!
^ Prior to cleaning and treating the engine with anti-corrosion wax, the fresh air openings, windshield and front fenders should be covered to protect the vehicle, to prevent cleaning and anti-corrosion material from entering the passenger compartment
^ Components such as the brake master cylinder, activated charcoal system (model 14O), distributor cap, electronic control modules, all uncovered openings on the engine and any components driven by a belt should also be protected.
^ In the case of diesel engines, it is also necessary to protect the vacuum pump and mask off the vent holes in the valve cover (arrows, Figures 1 and 2) for engines (601, 602, and 603) with positive crankcase ventilation (PCV) and/or exhaust gas recirculation (EGR).
^ The control modules and generator should not be subjected to direct jet spray from a cleaning system, specifically on the drive side in the area of the generator bearing and time belt pulley.
^ After cleaning, dry off components which may have become damp or wet.
^ Do not attempt to clean a hot engine, the engine should be cold or at most warm to the touch (specifically around exhaust components).
^ Do not apply anti-corrosion wax to the engine compartment until components are completely dry.
^ Do not apply anti-corrosion wax to exhaust system components, belts and belt pulleys.