Thermostat Housing: Service and Repair

WM 195519 Removing and installing housing for coolant regulator (thermostat housing) on 4.8-litre DFI engines

Technical values





Preliminary work

1. Remove intake-air distributor. -> 244619 Removing and installing DFI intake-air distributor Overhaul
2. Remove fuel distribution pipe. -> 243019 Removing and installing fuel distribution pipe (fuel rail) on DFI engines Service and Repair
3. Remove water pump. -> 195019 Removing and installing coolant pump on DFI engines Service and Repair
4. Remove transfer socket as far as the thermostat insert (thermostat insert remains fitted). For details, see -> 195819 Removing and installing coolant regulator (thermostat) on 4.8-litre DFI engines Service and Repair

Removing housing for coolant regulator (thermostat housing)

1. Disconnect the front coolant hoses from the two thermostat housing pipes. => Coolant hoses to radiator





Coolant hoses to radiator

2. Disconnect small coolant pipe at the side, pull it forward and set it aside. To do this, remove the screw -5- and pull off the pipe -1-.





Coolant return line on turbo engine M48/51





3. Loosen the vent line on the cylinder heads. => Vent line





Vent line

4. Remove screws on the wiring harness on the cylinder heads and at the water guide and loosen the wiring harness. => Wire harness for engine





Wire harness for engine

5. Remove screws on the thermostat housing and loosen thermostat housing in an upward direction. => Thermostat housing The coolant pipe -1- (bottom figure) remains fitted in the thermostat housing -1-.





Thermostat housing









Coolant guide





6. Remove the two coolant hoses from the coolant pipe behind the cable duct (figure shows several coolant hoses). => Coolant hoses Remove thermostat housing with coolant pipe.





Coolant hoses

7. Disconnect thermostat housing and coolant pipe if necessary. Replace sealing rings.

Installing housing for coolant regulator (thermostat housing)

1. Replace sealing rings and fit them into the crankcase. -4-





Thermostat housing





2. Insert coolant pipe with new sealing rings into the thermostat housing following disassembly. Insert sealing rings with grease 000.043.204.68.
3. Move thermostat housing and the fitted coolant pipe into installation position.
4. Connect coolant hoses.





Coolant hoses

5. Insert thermostat housing with coolant pipe and secure according to tightening sequence. => Tightening sequence for thermostat housing





Tightening sequence for thermostat housing

6. Screw coolant pipe onto collection pipe.





Coolant guide





7. Replace sealing rings on vent line and fit vent line on the cylinder heads. => Vent line





Vent line

8. Secure wiring harness. => Wire harness for engine





Wire harness for engine

9. Insert coolant pipe with new sealing ring and screw it on. -1-





Coolant return line





10. Fit front coolant hoses at the thermostat housing. => Coolant hoses to radiator





Coolant hoses to radiator

Subsequent work

1. Fit transfer socket as far as the thermostat insert. For details, see -> 195819 Removing and installing coolant regulator (thermostat) on 4.8-litre DFI engines Service and Repair
2. Fit water pump. -> 195019 Removing and installing coolant pump on DFI engines Service and Repair
3. Fit the fuel distribution pipe. -> 243019 Removing and installing fuel distribution pipe (fuel rail) on DFI engines Service and Repair
4. Fit intake-air distributor. -> 244619 Removing and installing DFI intake-air distributor Overhaul