Bosch washer/dryer leaving black marks

This thread was marked as solved. Here's a summary of the problem and the fix, generated from the discussion below.

Bosch washer/dryer leaving black marks on laundry

The problem

A Bosch washer/dryer, about 4 months old, was leaving severe black marks on white bedding and towels after the wash cycle, before drying. The owner reported this was the second Bosch washer/dryer with the same issue within 18 months, and that laundry was being ruined.

Likely cause

The accepted reply said washer/dryers can mark laundry if items get caught in the heating housing at the top of the door seal, often when overloaded. However, the owner checked this area and found nothing there, so this remained a suggested diagnosis rather than a confirmed cause.

What fixed it

The suggested check was to inspect and wipe around the top of the door seal where hot air enters the drum to see whether black residue could be reproduced. No repair was confirmed. The owner pursued the retailer and obtained a replacement machine of a different make.

Checks to try

• Cleaned the machine with Bosch washer cleaner
• Checked around the top of the door seal where hot air is pumped into the drum
• Used a clean cloth to rub around that area and found nothing there

Parts or tools mentioned

• Bosch washer cleaner
• Clean cloth