Cooling System: Testing and Inspection

Complaint: Coolant temperature indicator moves into red field while driving, coupled with simultaneous coolant loss.

Cause/remedy:
1. Retighten cylinder head bolts.
2. Correct coolant level and vent cooling system by intermittent acceleration with heater fully opened.

Attention! Open radiator cap only below 90 °C. First turn cap up to first detent only and read gauge pressure.
Danger! Proceed carefully !

3. Check radiator cap.
4. Check tension of V-belts on water pump and correct. Drive Belt
5. Check radiator fins (ribs) for external contamination. Blow out dirty radiator with compressed air from direction of engine.
6. Check radiator fins (ribs) between cooling tubes for firmly soldered joint (radiators made by Behr only).
7. Check cut-in point of temperature switch (100 °C) in thermostat housing.
8. Check function and direction of rotation of electrical supplementary fan.
9. Check thermostat element.
10. Check Viscofan coupling.
11. Check vent line between water pump and cylinder head for unobstructed passage.
12. Experimentally install a new radiator. Radiator
13. Experimentally replace thermostat housing while paying attention to free access from cylinder head to thermostat housing. Service and Repair
14. Remove water pump and check impeller with warm water pump (heated in water bath) for tight seat Check water pump housing for cavitation.
15. Check pressure loss with engine warm and radiator completely filled (disconnect overflow hose). Watch coolant surface for bubbles. In the event of bubbles, replace cylinder head gasket and check cylinder head for distortion and cracks, while removing pre-chambers for this purpose.

NOTE: Watching the coolant surface with the radiator cap removed and the engine running will often result in a wrung diagnosis.

When the radiator cap is removed, the pressure system is neutralized and the boiling point is lowered. Even though the telethermometer is not yet indicating 100 °C (212 °F), varying temperatures in cooling system may already now result in the formation of vapor bubbles, even though no mistake is in evidence. These vapor bubbles often result in the wrong diagnosis, cylinder head gasket leaking".

16. Remove rust and sludge deposts, as well as boiler scale from cooling system.



Complaint: Engine not warming up

Cause/remedy:
1. Remove thermostat element. Service and Repair
2. Check sealing seat of thermostat element for foreign particles (moulding sand, machining chips) and remove. Replace thermostat only when thermostat element is damaged or sealing surfaces are distortes.
3. If foreign particles are appearing again and again, flush engine well. For this purpose:
a) Disconnect all water hoses.
h) Remove water pump water pump housing and thermostat housing.
c) Remove all core hole plugs and core hole covers.
d) Flush engine housing and radiator with a strung water let
e) Flush heat exchanger.