2. Cold Weather Operating and Starting Hints

2.1 Engine Starting

Starting a diesel engine at low ambient temperatures should not be more difficult than starting a gasoline engine if the engine is well-maintained and the recommended starting procedures are adhered to. A diesel engine can be started under extreme temperature conditions.

To start a cold diesel engine the following procedure must be adhered to:

1. Turn idle speed adjuster to high idle (applicable to older models equipped with it).

2. At ambient temperatures below -18°C (0°F), depress the accelerator pedal fully three times prior to starting. This will assure free operation of the accelerator linkage. At these temperatures, the use of a block heater is definitely recommended.

3. Turn key in steering column lock to position "2". The charge indicator and preglow indicator lamps should come on.

4. The preglow process starts. When the Preglow indicator goes out, the engine is ready for starting.

5. Depress* the accelerator (and clutch, if applicable) pedal(s) fully. Turn key in steering column lock to start the engine. Release the key only when the engine fires regularly and runs smoothly. Then release the accelerator pedal slowly.

CAUTION:
Do not interrupt the starting process. In the case of a very cold engine, there is the danger of the engine failing to start during subsequent attempts, due to reduced battery capacity.

6. Allow the engine to run at high idle and drive away.

7. Reset idle speed adjuster (if applicable) to a lower idle speed after the engine has reached its operating temperature.

* Engines with ignition key controlled pre glow system (yellow indicator lamp) keep foot off accelerator during cranking. Accelerate after engine fires.

2.2 Selection of Diesel Fuel - Blending for Winter Operation

The use of the proper diesel fuel is one of the most important factors for cold weather starting and operation of a diesel engine.

Mercedes-Benz passenger car diesel engines can be operated on commercially available vehicular diesel No. 2 or No. 1 (ASTM D 975 No. 2 - D or No. 1 D). Marine diesel fuel, heating oil or the like must not be used.

One characteristic of diesel fuel, which can affect the starting and operation of diesel engines in cold weather, is the "Cloud Point". The cloud point is a temperature at which the paraffin and other waxes in the fuel begin to crystallize and separate within the fuel (with dropping temperatures).

These crystals are carried along with the fuel to the fuel filters. The filter will retain these crystals and can become clogged, preventing fuel from reaching the fuel injection pump.

To avoid malfunctions, No. 2 - D diesel fuel of a lowered cloud point, or wax appearance point, is marketed during the-cold season. In all cases, the cloud point of the fuel used should be no higher than the lowest ambient temperature at which the engine must be started.

At temperatures below 0°C (32°F), the use of No. 1 - D or "winterized" No. 2 - D diesel fuel is preferred. If these are not available, a certain quantity of kerosene must be added to No. 2 - D fuel. Mixing is only to be done while refilling the fuel tank. For best mixing results, it is recommended to fill in kerosene before diesel fuel.

Engine power and fuel economy may be affected according to the proportion of kerosene added. For this reason, keep the percentage of kerosene to the minimum necessitated by the ambient temperature. Adding of kerosene to No. 1 - D diesel fuel is not necessary and therefore not recommended.

NOTE:
Due to the variety of diesel fuel qualities in different areas, the preceding comments should be regarded as a general guideline.





The table shown can be used as a reference if adding of kerosene becomes necessary. The mixing ratios shown refer to the total mixtures. We recommend not to exceed a 50% mixture ratio, even below -10°C (+14°F).

The use of additives for improved winter operation may be counter-productive because of possible undesirable chemical reactions with the additives already provided by the fuel manufacturers.

WARNING:
Always follow basic safety rules when working with any combustible material. Do not fill the fuel tank or mix diesel fuel and kerosene when smoking, near an open flame or while the vehicle's engine is running. An explosion or fire can result.