The Aluminum crush washers used on the OM617, OM616 and likely other Mercedes is a common spot to have a slow fuel leak.
Many times that crush washer doesn’t seal up quite 100% so it seeps fuel.
There is also a later version of the housing (02 style) that uses 2 o-rings instead of a 1 o-ring and a crush washer to seal, but sometimes those housings would seep too.
Here is a super simple and cheap way to stop those pesky fuel leaks.
Get some new o-rings and a updated crush washer for your 01 style housing:
Bonded rubber crush washer:
M10x15x2.5 Viton O-ring:
Here is what you would need for an 02 housing:
M14x19x2.5 Viton O-ring:
M10x15x2.5 Viton O-ring:
