Coolant Pump and Thermostat Overview
Coolant Pump and Thermostat Overview
• When the engine is warm the cooling system is under pressure. If necessary release pressure before beginning any repair work.
• Install only approved clamps for securing hose connections, refer to the Parts Catalog.
• Use spring-type clip pliers to installing spring clips.
• Always replace gaskets and seals.
• The arrows on the coolant pipes and coolant hoses must line up across from each other.
Part 1, Belt Pulley Side
1 Cylinder Block
2 Engine Oil Cooler
3 Bolt
• 25 Nm
4 Bolt/Nut
• 10 Nm
5 to the Heater Core, Bottom
6 Guide Tube
• For the oil dipstick.
7 Pre-Warmer
• Not available in the US/Canadian market.
8 Bolt
• 25 Nm
9 O-ring
• Always replace.
10 Retaining Clip
• Make sure it is secure.
11 Front Coolant Line
12 Connecting Hose
13 Coolant Thermostat Housing Cover
14 to the Radiator Lower Connection
15 Bolt
• 5 Nm
16 O-ring
• Always replace.
17 Coolant Thermostat
• Removing and installing, refer to => [ Coolant Thermostat ] Coolant Thermostat.
• Note the installed position:
The valve must be at the top.
• Checking (thermostat installed):
Refer to "Guided Functions" in the vehicle diagnostic tester.
• Checking (thermostat removed):
Heat up the thermostat in water
Starts to open: approximately 87 °C (188.6 °F) Opening ends: approximately 102 °C (215.6 °F) opening distance: minimum 7 mm
18 Seal
• Always replace.
19 Bolt
• 25 Nm
20 Coolant Thermostat Housing
21 Seal
• Always replace
22 Accessory Bracket
23 O-ring
• Always replace.
24 Bolt
• 9 Nm
25 Coolant Hose
• To the front coolant pipe.
• To the expansion tank, bottom connection.
26 Bolt
• 10 Nm
27 Coolant Pump
• With a integrated silicone seal for the cylinder block.
• Removing and installing, refer to => [ Coolant Pump ] Coolant Pump.
Part 2, Transmission Side
1 Adapter (Coolant Connection)
• Pressed in the cylinder head
• Clean before installing the flange => [ (Item 18) Flange ].
- If necessary, remove coolant deposits using a copper wire brush or fine sandpaper (minimum 100 grit).
• If the adapter is worn, replace it using liquid locking fluid (D 000 600 A2).
2 Lock Ring
3 Seal
• Replace after removing the coolant thermostat housing. Refer to => [ Coolant Thermostat ] Coolant Thermostat.
4 to the Expansion Tank, Top Connection
5 Rear Coolant Pipe
6 Bracket
• For the heated oxygen sensor (G39).
7 Bolt/Nut
• 10 Nm
8 Heat Shield
9 to the Heater Core, Top Connection
10 Supply Hose
11 Bypass Thermostat
• Only for vehicles with a automatic transmission.
• Overview, refer to => [ Bypass Thermostat Overview ].
• Checking
12 to the Transmission Oil Cooler
• Only for vehicles with a automatic transmission.
13 from the Heater Core, Bottom Connection
14 from the Transmission Oil Cooler
• Only for vehicles with a automatic transmission.
15 Return Hose
16 Coolant Line
• Bolted to flange => [ (Item 18) Flange ].
17 to the Flange
18 Flange
19 to the Radiator, Upper Connection
20 to the Radiator, Upper Connection
21 Supply Hose
22 Engine Coolant Temperature Sensor (G62)
23 O-ring
• Always replace.
24 Retaining Clip
• Make sure it is secure.
Bypass Thermostat Overview
1 Spring bracket
2 Lower part of housing
Note the installed position: Arrow points toward transmission fluid cooler
3 Operating element
4 Spring
5 O-ring
6 Upper part of housing
Bypass Thermostat, Checking
- Remove the operating element - 3 - and heat in a hot water bath.
Starts to open: approximately 75 °C (167 °F)
Opening end: approximately 85 °C (185 °F)
Opening lift: approximately 5 mm