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8.17.9 Preheater – Overhaul
Preconditions
☑
Engine is stopped and starting disabled.
DANGER
Electric voltage supply for operation.
Danger of burns and fatal electric shock!
• Make certain that the power supply to the product is switched off before starting work. Secure
against unintentional switching on!
WARNING
Coolant is hot and under pressure.
Risk of injury and scalding!
• Let the engine cool down.
• Wear protective clothing, gloves, and goggles / safety mask.
Preheater – Overhaul
1.
Disconnect power supply to heating element.
2.
Close shut-off valves in coolant lines upstream and downstream of preheating unit.
3.
Drain coolant at drain valve into a clean vessel.
4.
Clean and flush coolant circuit.
5.
Check hoses for cracks and other damage. Replace as necessary.
6.
Check wiring for damage and overheating.
7.
Allow heating element to cool down.
8.
Remove housing cover (7).
9.
Remove screws of connection housing (4)
and remove connection housing (4) and O-
ring (3).
10.
Loosen thermostat clip (6).
11.
Remove terminals on thermostat (5) from
blade terminals of measuring unit.
12.
Replace thermostat (5) if necessary.
13.
Remove screws of heating element plate (2).
14.
Remove heating element plate (2) with heat-
ing element (8) from tank (9).
Note:
Make sure the O-ring (1) is properly installed.
15.
Clean heating element (8) and tank (9).
16.
Install heating element plate (2) with heating
element (8).
17.
Install connection housing (4) and O-ring (3).
18.
Install housing cover (7).
19.
Connect heating element to power supply.
20.
Remove pump from volute and check for resi-
dues in impeller and lines.
21.
Connect hoses and open shut-off valves.
22.
Check preheater for leakage and correct op-
eration (→ Page 254).
23.
Check coolant level (→ Page 242).
252 | Coolant System, General, High-Temperature Circuit | MS150123/01E 2017-05
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