Coolant specifications - BB00.40-P-0310-01A

1. Terms used 

   Antifreeze with corrosion inhibitor, KFM:  Part of the coolant for combustion engines as corrosion protection and antifreeze protection, for lowering the freezing point as well as increasing the boiling point.

   Coolant, KM:  Mixture of antifreeze with corrosion inhibitor and water for the cooling of engines. Normally, coolants consist of antifreeze with corrosion inhibitor and water. The coolants must perform the following tasks in the cooling system, among other things:

   • Transfer of heat
   • Corrosion and cavitation protection for all components in the cooling system
   • Lowering of freezing point (antifreeze protection)
   • Increasing of boiling point
   • Resistance against microorganisms
   • Stability and durability
   • No foaming

   Coolant additives:  Anticorrosion agent that can be used mixed with water for special applications. The mixture does not contain any antifreeze protection!

   MB approval:  Marking of the coolants or antifreezes with corrosion inhibitor that are tested by Daimler AG and approved for corresponding use, see FOR PASSENGER CARS AND VEHICLES WITH PASSENGER CAR COMBUSTION ENGINES . On containers with tested brand-name products, you will find a note, e.g. MB approval 325.0. 

2. Overview 

   FOR PASSENGER CARS AND VEHICLES WITH PASSENGER CAR COMBUSTION ENGINES give an overview of the application of the tested antifreezes with corrosion inhibitor and the maximum change intervals. Note the MB approval before using a coolant. With the right use of tested coolant qualities with MB approval, you maintain the full protection of the cooling system. The vehicles with combustion engine are defined in the assignment across the engine model series. Table 1 therefore applies for all vehicles with an OM642 engine, for example, irrespective of the registration of the vehicle.

   FOR PASSENGER CARS AND VEHICLES WITH PASSENGER CAR COMBUSTION ENGINES
   
   

   Sheet No.	Engine series		Change interval years/km
   	M100/M200	OM600
   325.0 or 326.0	•	•	15/250.000 Whichever occurs first must be observed; Exception: Shorter change intervals are stipulated in the vehicle's maintenance manual

   Coolants or antifreezes with corrosion inhibitor that are listed in tables on different sheet numbers must not be blended, as a considerably lowered corrosion protection may ultimately damage the cooling system. In general, mixtures of various antifreezes with corrosion inhibitor offer a lesser performance than the specially adjusted active components of a formulation.

   The sheet numbers: 325.x show the antifreeze with corrosion inhibitor, the corresponding sheet number 326.x shows the finally mixed coolant. The antifreezes with corrosion inhibitor must be mixed with water before use.

   Vehicles with fuel cell drive require a special coolant for the cooling of the fuel cell. Coolants for fuel cell drives can only be refilled at an F-Cell service point.

3. Coolant 

   The coolants and antifreezes with corrosion inhibitor are based on ethylene glycol as the antifreeze protection component, but differ with regard to the other ingredients, e.g. for corrosion protection, table 3.

   TABLE 3: SPECIFICATIONS FOR OPERATING FLUIDS SHEET NUMBER AND COOLANT TYPE
   
   

   Coolant sheet no.	Antifreeze with corrosion inhibitor sheet no.	Inhibitors		Free from
   		inorganic	organic
   326.0	325.0	Si, B	•	Amine, phosphate
   326.2	325.2	Si, B	•	Amine, phosphate
   326.3	325.3		•	Nitrite, amine, phosphate, borax, silicon
   326.5	325.5	SI	•	Nitrite, amine, phosphate, borax

   The coolant must remain in the cooling system year round to protect against corrosion under all operating conditions. Corrosion may lead to poor heat output and engine overheating!

   1. 3.1. Mixing ratio 

      In general, a coolant must be used with approx. 50 vol.-% antifreeze with corrosion inhibitor and 50 vol.-% water. The water quality must satisfy the requirements in the following chapter. The antifreeze protection of this mixture is good up to approx. -37°C. Even with extremely low ambient temperatures, not more than 55 vol.-% antifreeze with corrosion inhibitor is to be used. With 55 % antifreeze with corrosion inhibitor, the maximum antifreeze protection, approx. -45°C, of a water-based ethylene glycol solution is reached; a higher KFM portion lowers the antifreeze protection and the heat dissipation in the engine worsens.

      TARGET CONCENTRATION OF ANTIFREEZE WITH CORROSION INHIBITOR AND WATER
      
      

      Sheet No.	Mixing ratio
      	KFM vol %	Water vol %
      325.0	50	50
      325.2	50	50
      325.3	50	50
      325.5	50	50
      311.0	1	99
      312.0	10	90

      The boiling point of the coolant increases with the share of antifreeze with corrosion inhibitor. In the vehicle, the coolant is also protected against boiling by means of the pressure in the cooling system. By raising the pressure, the boiling temperature of the coolant can be increased further.

      Only approved products offer reliable protection of the cooling system. In special cases (commercial vehicle engines, no antifreeze specification), coolant additives can be used that are primarily anticorrosion additives.

4. Water quality 

   Clean and, where possible, soft water should be used for preparing the coolant. Drinking water often meets the desired requirements. Information concerning the water quality of drinking water is available from the local water-plant authorities or the official water utilities on request.

   If no information is available on the water quality or no suitable water is available, distilled or deionized water is to be used to prepare the coolant.

   Sea water, brackish water, brine and industrial waters are not suitable. Salts may promote corrosion or form disruptive deposits.

   The analysis values of the water for mixing in coolants must be within the limits of table.

   WATER QUALITY
   
   

   Water quality		min	max.
   Alkaline earth ions	mmol/l		2.7
   Hardness	°dH		15
   Chloride	mg/l		80
   Chloride + sulfate	mg/l		160
   pH-value	-	6.5	8, 0

   1° dH = 1.783 mmol/l alkaline earth ions = 7.147 mg/l Ca²⁺ or 4.336 mg/l Mg²⁺

   With the use of premixed coolant, take note not only of the MB approval but also the adherence to the concentration (50/50).

5. Monitoring coolant operation 

   During operation, the corrosion inhibitors of the coolant are consumed and the mixing ratio may be changed due to the evaporation of water. Regular monitoring of the coolant is therefore important for trouble-free operation of the engine.

   The inspection of the mixing ratio should be conducted with suitable apparatuses. To do so, the density in acc. with picture 1 or the refractive index in acc. with picture 2 can be used for the determination. The specifications on the mixing ratio may differ slightly for individual coolants from the values in pictures 1 and 2.

   Fig 1: Antifreeze Quantity Calculation Reference Chart

   Courtesy of MERCEDES-BENZ USA
   Fig 2: Refractive Index Of KFM/Water Mixtures

   Courtesy of MERCEDES-BENZ USA

   If only 40 vol.-% or more than 55 vol.-% antifreeze with corrosion inhibitor is in the coolant, the mixing ratio must be corrected immediately. To calculate the refill quantity, the following calculation aid can be used:

   Fig 3: Calculation Of Antifreeze Quantity With Too Low Concentration

   Courtesy of MERCEDES-BENZ USA
   REFRIGERANT PROTECTION/CONCENTRATION TABLE (APPROX.)
   
   

   °C	-10	-14	-15	-18	-20	-23	-25	-27	-30	-33	-35	-40
   vol %	20	25	26	30	32	35	37	40	42	45	47	50

6. Disposal of coolants 

The coolants are biologically-degradable material. All statutory regulations or waste water regulations in each individual country with regard to the disposal of used coolant must be observed. It is recommended to have the possibilities available for disposing of materials explained by the local responsible water authorities.