Important: If you need to top up the coolant, you should not add only distilled water, antifreeze and anti-corrosion agent are also needed.
Coolant level sensor
The coolant level sensor for gasoline engines has the same structure as the sensor for diesel engines. All practical advice, sensor verification work and its operation are similar to those described for diesel engines in section 4 «Diesel engines».
Coolant replacement
"120,000 km every 4 years"
4 cylinder engine
1. Carefully unscrew the cap of the expansion tank, release excess pressure from the cooling system.
Attention! Be careful, a hot engine can cause burns.
2. Set the heater control on the instrument panel to the maximum heating position.
3. Remove the crankcase protection from below.
Pic. 5.26. Radiator drain plug: 1 - cork
4. Place a receiving container under the radiator and the engine, on the bottom of the radiator unscrew the drain plug 1 (pic. 5.26) and drain the coolant. A short hose can be put on the fitting on the side (inner diameter 12 mm), to direct the liquid into the container.
Pic. 5.27. Putting the hose on the fitting of the cylinder block: 1 - hose
5. Attach hose 1 (pic. 5.27) 14 mm ID on the drain fitting on the right side of the engine block and open it.
6. To better drain the coolant, remove the cap from the expansion tank. Drain the coolant and cover the receiving container.
7. After completely draining the coolant, flush the radiator with clean water.
8. To fill in the coolant, screw on the plug on the engine block and the radiator drain plug.
9. Install the crankcase protection.
Pic. 5.28. Radiator filler neck
10. Slowly pour coolant through the filler neck (pic. 5.28), while the liquid level should reach the protrusion at the bottom of the expansion tank (visible when lid is open), which corresponds to a distance of 5.5 cm from the upper edge of the filler pipe.
11. Start the engine and let it run at high speed for about 2 minutes. Set the heater to maximum heating. At the same time, constantly add coolant to the expansion tank.
12. Wrap a cover of a broad tank.
13. Let the engine run until the fan turns on, then stop the engine.
14. Check the coolant level, top up if necessary.
15. Warm up the engine. In this case, the air from the cooling system will exit through the cap of the expansion tank. Check the coolant level again. Add some water if necessary.
Features of replacing the coolant of a 6-cylinder engine
1. Turn the 2-stage expansion tank cap 1/2 turn and relieve system pressure. Rotate the cover and remove it.
Note. On a 6-cylinder engine, the cover has two pressure stages. As a result, after the engine stops, the pressure in the system can rise to 2 bar, and the liquid will not flow out.
2. Before filling the system, unscrew the temperature sensor on the thermostat housing.
3. Fill the cooling system until fluid flows out of the thermostat opening.
4. Wrap the temperature sensor and add fluid to the norm.
5. Screw on the cap so that the protrusion on the expansion tank is fixed.
Features of replacing the coolant of an 8-cylinder engine
6. The engine has a two-stage expansion tank cap.
7. There are two drain valves on the engine block.
Checking the coolant
Regularly check the concentration of antifreeze in the coolant before the onset of cold weather, especially if you added water to the system during operation.
To check, you will need a densimeter - a device for measuring density. You can convert the resulting density value into the value of the freezing point of the coolant.
Sequence of work
1. Start the engine and warm it up until the upper coolant inlet to the radiator becomes warm.
2. Carefully open the expansion tank cap.
Attention! There is a danger of getting burned.
Pic. 5.29. Checking the coolant with a densimeter
3. Take the coolant with a densimeter and determine the density by the position of the float (pic. 5.29).
Note. The concentration of antifreeze for our latitudes should prevent freezing of the coolant to a temperature of -37°C, for areas with a cold climate - up to -45°C.
Attention! Daimler-Benz only allows the use of homemade antifreezes. In case of malfunctions caused by the use of antifreeze from other manufacturers, the warranty is void.
4. Add antifreeze to the cooling system in the amount indicated in Table. 5.5 to ensure the required freezing point for the vehicle in the region.
Table 5.5. The amount of antifreeze concentrate to obtain the required value of the freezing point of the coolant
Table usage example. If the density of antifreeze on a 2.0 liter engine corresponds to a freezing point of -10°C, then in order to obtain a freezing point of -37°C, it is necessary to drain 3.1 liters of coolant and pour the same amount of antifreeze concentrate into the system. To obtain a freezing point of -45°C, 3.7 liters must be replaced.
5. Close the expansion tank cap, test drive, check the antifreeze concentration again.