Thermostat: Service and Repair

11 53 000 Removing And Installing/Replacing Coolant Thermostat (N54)

Special tools required:

WARNING:
Risk of scalding.
Only perform this work after engine has cooled down.

Recycling:
Catch and dispose of drained coolant in a suitable container.
Observe country-specific waste disposal regulations.

Necessary preliminary tasks:
- Remove front underbody protection.
- Remove fan cowl with electric fan.

Disconnect coolant hoses (arrows) from thermostat using grips.

IMPORTANT:
Risk of damage.
Coolant emerges when the coolant hoses are detached from the coolant thermostat.
Cover surrounding components and plug connections with suitable apparatus

Unlock snap fastener on coolant hose (3).
Detach coolant hose (3) and lay to one side.
Disconnect plug connection (4).

Installation note:
plug connection (4) must snap audibly into place.

Unfasten hose clamp (1).
Tightening torque 11 53 12AZ.

NOTE: Coolant hose (2) is removed together with coolant thermostat.

Release spring band clamp (2) with special tool 17 2 052.
Detach coolant hose (3) and lay to one side.
Unlock snap fastener on coolant hose (1).
Detach coolant hose (1) and lay to one side.

Release screw (1).
Tightening torque 11 53 11AZ.

IMPORTANT:
Risk of breakage.
The mounting of coolant thermostat (2) (not shown) may break if removed incorrectly.

Slide coolant thermostat (2) together with coolant hose (4) approx. 4 cm in direction of arrow from holder (3).
Lift out coolant thermostat (2).

Unfasten hose clamp (5).
Tightening torque 11 53 12AZ.
Detach coolant hose (4).

Installation note:
Pre-install coolant hose (4) on coolant thermostat (2).
Slide mounting (3) of coolant thermostat (2) into holder at position (1).

Assemble engine.
Fill cooling system and check for tightness. Observe capacities.

Installation note:
Check coolant hoses for cracks and damage.
Renew coolant hoses as required.

Recommendation:
On vehicles older than five years, renew coolant hoses.

Check function of cooling system.