...the coolant hose going inside the firewall (passenger's side on left hand drive models). Is it a pump to activate a valve that controls coolant flow to the heating system ? It's black and cylindrical in shape. Somehow I have a spare in the trunk and I have been trying to figure out what was it for...until I noticed the same-looking part on that coolant hose when I was bypassing my heating system (leaking heater core).
Jens, I did just like you said removing the 2 hoses going in the firewall and putting a third hose between them with 2 adapters. Works like wonder and no more coolant leaks....I still have to get a core though.