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-Heater
• Only on vehicles with a engine pre-heater.
8 Bolt
• 25 Nm
9 O-ring
• 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 (coolant thermostat installed):
Refer to "Guided Functions" in the vehicle diagnostic tester.
• Checking (coolant 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) Open distance: at least 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.
26 Bolt
• 10 Nm
27 Coolant Pump
• With a integrated silicone seal for the cylinder block.
• Removing and installing, refer to => [ Coolant Pump ] Service and Repair.
Part 2, Transmission Side
1 Adapter (Coolant Connection)
• Pressed into the cylinder head.
• Clean before installing the flange.
- If necessary, remove any coolant deposits using a copper wire brush or fine sandpaper (minimum 100 grit).
• If 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 => [ By-Pass Thermostat Overview ].
• Checking.
12 to the Transmission Oil Cooler
• Only for vehicles with a automatic transmission.
13 from the Heater Core, Bottom
14 from the Transmission Oil Cooler
• Only for vehicles with a automatic transmission.
15 Return Hose
16 Coolant Line
• Bolted to the 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.
By-Pass Thermostat Overview
1 Spring bracket
2 Lower part of housing
Note the installed position: The arrow points toward the transmission fluid cooler
3 Operating element
4 Spring
5 O-ring
6 Upper part of housing
Checking the Bypass Thermostat:
- Remove the operating element - 3 - and heat it 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