There is a very short hose between the engine block and the thermostat housing.Mine broke Is it possible to replace it w/o removing the housing and the water pump? 1990 MB 190.What does it mean high pressure in the cooling system?Thank you for your help.

We call that water pump bypass hose you have remove water pump to replace that hose...may be is time to replace water pump too.
by the way replace thermostat at same time.

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MB STARS Master Guild Technician,12 years MB tech
5 years independent shop owner

The high pressure is only when the engine is hot! It runs as much as 1.4 bar of pressure when hot and will hurt you if you take off the cap at that time.

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM