ar2010a2455a

Testing the coolant thermostat

Type ar · topic 20.10 · version 0102 · 2006-08-07

Applies to: ENGINE 457.939 /945 /946 /949 in MODEL NAB372.124 ENGINE 457.939 /945 in MODEL NAB372.317

Where it sits

Function group 1 Engine › 20 Engine cooling system › 20.10 Coolant pump, coolant thermostat — Series 372 (models 124, 317)

EinPAS 15 Engine › 15.25 Engine cooling system › 15.25.30 Pump/thermostat/preheater — Series 372 (models 124, 317)

Also applies to engines/gearboxes: 457 939, 457 945, 457 946, 457 949

AR20.10-A-2455A

Testing the coolant thermostat

19.7.06

ENGINE 457.939 /945 /946 /949 in MODEL NAB372.124

ENGINE 457.939 /945 in MODEL NAB372.317

Testing the coolant thermostat

W20.10-0005-04

1 Coolant thermostat

1/1 Main valve

1/2 Bypass valve

Checking

1

Remove coolant thermostat (1)

AR20.10-A-2460A

Danger!

Risk of injury to skin and eyes caused by handling hot or glowing objects.

Wear safety gloves, protective clothing and safety glasses, if necessary.

AS00.00-Z-0002-01A

2

Suspend coolant thermostat (1) in a vessel filled with water

The coolant thermostat must not be heated directly with a naked flame.

3

Warm water using a suitable heat source

Stir the water to ensure the heat is evenly distributed.

4

Monitor water temperature

Reduce the rate at which the water is heated up to 1 - 2°C/minute about 8°C before start of opening is reached. The coolant thermostat (1) must open visibly as soon as the water temperature has reached the temperature of start of opening.

*BE20.10-N-1001-02G

5

Continue heating water

The main valve (1/1) must have reached the fully open position 6 to 8 minutes after start of opening if an even temperature rise is maintained.

6

Determine water temperature and stroke of the main valve (1/1) for a fully opened main valve (1/1)

If noted values are not in the test value range, the coolant thermostat (1) must be replaced.

*BE20.10-N-1002-02G

7

Install coolant thermostat (1)

AR20.10-A-2460A

Check values for the coolant thermostat

Number

Designation

Engine 457.9

BE20.10-N-1001-02G

Coolant thermostat

Start of opening

°C

83 (2)

BE20.10-N-1002-02G

Coolant thermostat - main valve

Fully open

°C

95

Stroke

mm

8

Referenced documents