Attention! In order to continue the trip, you can also, especially in summer, add clean water. In this case, it is necessary to make adjustments to the composition of the radiator coolant as soon as possible.
6-cylinder or 4-cylinder engine with air conditioning: The coolant level in a cold engine (coolant temperature approx. +20°C) must reach the interface between the black top part and the transparent bottom part of the expansion tank.
4-cylinder engine without air conditioning: the coolant level in a cold engine (coolant temperature around +20°C) should reach the mark in the radiator filler pipe.
Add coolant if the level is too low.
To avoid engine damage, add coolant when the engine is cold.
Caution! Open the locking cap carefully when the engine is hot. There is a risk of scalding! When opening, place a rag over the locking cap. If possible, open the locking cap only when the coolant temperature has dropped below 90°C.
When opening, first lift the locking cap slightly to release excess pressure. Then turn the cap further and remove it.
Perform a visual inspection if the coolant level drops over a short period of time.
Antifreeze check
The following testing tool is required: Test hydrometer.
Article based on data from the website (MercedesMan.ru)
To avoid any risk, the concentration of antifreeze should be checked regularly before the start of winter, especially if clean water has been added occasionally.
1. Warm up the vehicle until the upper coolant hose leading to the radiator is warm.
2. Carefully open the sealing cap on the expansion tank.
Caution: Do not open the cap when the engine is hot.
3. Use a measuring hydrometer to collect some coolant and read its density using the float.
In our latitudes, engine protection against freezing must be guaranteed down to –30°C, and in very cold climates – down to –45°C.
Adding coolant concentrate (Mercedes Benz)
Attention! Since some parts of the cooling system are made of aluminum, only suitable antifreeze and anticorrosion agent approved for use by Mercedes-Benz should be used for these purposes.
Example: Measuring the freeze protection of a 4-cylinder engine (without air conditioning) using a hydrometer guarantees this protection down to a temperature of -20°C. In this case, drain 1.3 liters of coolant from the cooling system and then add 1.3 liters of pure antifreeze concentrate. This guarantees engine protection against freezing down to a temperature of -37°C. If you want to guarantee engine protection against freezing down to -45°C, replace 1.7 liters of fluid.
Measured value,°C | ||||
| 0 | –10 | –20 | –30 | |
Quantitative difference, l | ||||
Petrol engines | ||||
| 4-cylinder -37° / no air conditioning -45° | 4,0 / 4,4 | 2,4 / 2,8 | 1,3 / 1,7 | 0,5 / 0,9 |
| 4-cyl. -37°/ with air conditioning -45° | 4,5 / 5,0 | 2,7 / 3,2 | 1,4 / 1,9 | 0,5 / 1,0 |
| 6-cylinder –37°/ –45° | 5,0 / 5,5 | 3,0 / 3,5 | 1,6 / 2,1 | 0,6 / 1,1 |
Diesel engines | ||||
| Engine 2.0L –37° / –45° | 4,0 / 4,4 | 2,4 / 2,8 | 1,3 / 1,7 | 0,5 / 0,9 |
| Engine 2.0 l –37° / –45° with air conditioning | 4,5 / 5,0 | 2,7 / 3,2 | 1,4 / 1,9 | 0,5 / 1,0 |
| Engine 2.2L –37° / –45° | 3,5 / 3,9 | 2,1 / 2,5 | 1,1 / 1,5 | 0,5 / 0,8 |
| Engine 2.2 l –37° / –45° with air conditioning | 3,8 / 4,1 | 2,3 / 2,6 | 1,2 / 1,6 | 0,5 / 0,8 |
| Engine 2.5 l –37°/ –45° | 3,8 / 4,1 | 2,3 / 2,6 | 1,2 / 1,6 | 0,5 / 0,8 |
Attention! The values given in the table are valid for a coolant temperature of approximately +20°C.
Close the radiator cap and check the antifreeze protection again after a test drive.
Checking the tightness of the cooling system
Check coolant hoses for porous areas by squeezing and bending, replace any hoses that have become stiff.
Hoses must not be placed too short on the connecting pipes.
Check the rubber hose clamps for tight fit and replace the clamps if necessary.
Check the radiator cap seal or expansion tank for damage.
Caution! Too low a coolant level can also be caused by an incorrectly tightened radiator cap (no tightness).
A clear coolant leak and/or oil in the coolant, as well as white exhaust clouds when the engine is hot, indicate a bad head gasket.
Warning! Sometimes it is difficult to detect the leak location. In this case, we recommend using a pressure test in a car repair shop (a special device is required). At the same time, you can also check the safety valve of the radiator cap.