Body - Corrosion Between Underride Guard and Both Bumpers

Corrosion of threaded connection between stainless steel underride guard and front and rear bumper

Topic number LI88.20-P-051115

Version 1

Design group 88.20 Bumpers

Date 04-09-2012

Validity W164 with

code (U89) Offroad appearance package
code (900) Exterior chrome package
code (P96) Sport package exterior
code (P94) Appearance package

Reason for change

Complaint:





Corrosion of threaded connection between stainless steel underride guard and front and/or rear bumper (see Figure 1).





Attachments

Cause:
Depending on the condition of the body, the customer complaint may be due to poor bolt quality, crevice corrosion or discolored wax*,

which is interpreted as corrosion by the customer

*Important:
The preservation agent used on the W164 turns red under the influence of water and oxygen. Its appearance resembles corrosion and is perceived as such by the customer. In contrast to corrosion effects, the red discolored wax can be removed in places using a plastic scraper. In this way corrosion can be distinguished from wax residues.

Remedy:
1. Thoroughly clean stainless steel underride guard with suitable polish; replace bolts

2. Apply preservation agent to underside of bolt heads

3. Install bolts

4. Thoroughly remove wax on bolt head and on underride guard using a rag, as wax residues on the bolt head can turn red.

Important:
Plastic washers must not be used because these can cause crevice corrosion.

Valid for: Damage code: 8820A, 8820B, 8810C, 8830B Damage type: 47 - corroded/oxidized





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WIS-References