Checking fluid levels, leak control (Mercedes-Benz G-Class W463)

Note: The following describes the procedure to be performed on a monthly basis. Descriptions of other fluid level checks can be found further in the relevant Sections devoted to specific maintenance procedures. Regardless of the intervals specified in the Schedule, try not to ignore the occurrence of fluid leaks under the vehicle - such signs indicate the presence of faults that require immediate correction.

Attention! When checking the level of any working fluid, the car must be positioned strictly horizontally!

Fluids are an integral part of lubrication, cooling, braking and windshield washing systems. Due to normal consumption and tendency to contamination during vehicle operation, periodic checks of condition/levels and replacement of working fluids should be performed - please read the requirements Specifications to the types of compounds used and the filling volumes of the corresponding systems.

Engine oil

Visual inspection of leaks

1. If the power unit is noticeably oiled and there is a high oil consumption, carefully inspect the areas where leaks are most likely to develop:

• Engine oil filler cap seal - check for cracks and other mechanical damage;
• Components of the crankcase ventilation system (in particular, the ventilation hose running from the cylinder head cover to the intake air duct);
• Cylinder head cover(s) gasket;
• Cylinder head gasket(s);
• Sealing element of the drain plug of the engine oil pan;
• Oil filter gasket - carefully examine the place where the filter fits to the mounting flange;
• Oil pan gasket;
• Front and rear crankshaft oil seals.

2. Wrap the generator in plastic, spray the engine with a regular cold cleaner, then, after a short time, wash the unit at a car wash.



3. Sprinkle the joints of the mating surfaces and the sealing elements of the power unit from the outside with lime or talc.

4. Check the oil level and make adjustments if necessary (see below).

5. During the short (about 30 km) trips (preferably on the expressway) warm up the engine to normal operating temperature - hot oil is more fluid and seeps through leaks more easily.

6. Park the car in a safe place and, using a lamp, examine the engine to locate the sources of oil leaks. Eliminate the causes of leaks.

Checking the level

Note: The maximum permissible engine oil consumption is 1l/1000 km, the actual level of oil consumption depends on driving style - frequent driving with high engine speeds leads to increased oil consumption.

1. The engine oil level control function is included in the "Standard indication" section of the main menu of the on-board computer (consult your car's operating manual - ask at automotive literature stores).

2. A physical check of the oil level is carried out using a dipstick inserted into the guide tube and lowered into the engine to the bottom point of its oil pan (see illustrations Engine compartment of petrol models (using the G55 AMG as an example), Engine bay of diesel models G270 CDI and Engine bay of diesel models G400 CDI). The oil level should be checked before the first trip of the day, or about 5 minutes after the engine has been stopped. If the check is performed immediately after the engine has been turned off, the results will not adequately reflect the situation, since some of the oil will be distributed throughout the internal galleries and components of the engine.



3. Remove the dipstick from the guide tube and wipe the blade dry with a clean rag or paper towel. Insert the dipstick back into the tube until it stops, then remove it again. Inspect the dipstick blade and estimate the size of the area wetted with oil. The oil level should be between the upper and lower marks on the dipstick blade. If necessary, add the appropriate amount of oil of the required grade to the engine.

Note: To raise the level from the lower mark on the dipstick blade to the upper mark, approximately 2 liters of oil are required.

4. Lowering the level beyond the lower limit of the permissible range leads to the development of oil starvation of the engine and is fraught with serious mechanical damage to the latter. Also try not to overfill the oil above the upper mark, as this can lead to throwing of spark plugs or failure of the power unit seals as a result of excessive pressure increase.

5. In order to fill the engine with oil, it is necessary to remove the threaded cap of the filler neck (see illustrations) Engine compartment of petrol models (using the G55 AMG as an example), Engine bay of diesel models G270 CDI and Engine bay of diesel models G400 CDI). To avoid oil splashing when adding oil to the engine, use a funnel or a long-nosed oiler. After adding oil, screw on and tighten the filler cap securely, then start the engine and carefully inspect the drain plug and the surface of the oil filter mating with the block for signs of leaks. Turn off the engine, wait 5-10 minutes for the oil to drain into the pan, then check its level again.

Note: Excess oil must be drained or pumped out of the crankcase - excessive engine oil level can cause failure of the catalytic converter. Make sure the filler cap is securely tightened.

6. Checking the engine oil level is an important preventive maintenance procedure for the engine. A constant decrease in the level indicates the presence of oil leaks due to failure of seals, damage to sealing gaskets, wear of piston rings or valve guides. If the oil is milky in color or consistency, or if there are drops of water in it, this indicates possible damage to the cylinder head gasket, or the formation of cracks in the body of the head(s) or block. The check must be done without delay. When measuring the oil level, always also check its condition. Use your thumb and forefinger to remove traces of oil from the dipstick blade - if there are small metal particles in it, the oil must be replaced (see Section Changing engine oil and oil filter).

Engine coolant

Warning! Do not allow antifreeze to come into contact with exposed areas of the body or painted surfaces of the vehicle. Wash away accidental splashes immediately with plenty of water. Remember that antifreeze is a highly toxic liquid and its ingestion, even in small quantities, can have the most serious consequences, including death. Never leave antifreeze stored in a loosely closed container; immediately collect any coolant spilled on the floor. Remember that the sweet smell of antifreeze can attract the attention of children and animals. Consult with local authorities about methods of disposal of used coolant - in many regions of the world, special collection points for various types of waste have been set up. Never pour old coolant into the sewer or onto the ground!

Note: Non-toxic grades of antifreeze have been developed in recent years, but they must still be disposed of in an orderly manner.

1. All vehicles covered by this Manual are equipped with a compensating cooling system operating under excess pressure. The plastic expansion tank is located on the right in the engine compartment and is connected by hoses to the radiator and the water jacket of the power unit (see illustration Engine compartment of petrol models (using the G55 AMG as an example)). As the engine warms up during operation, the expanding coolant fills the tank. When the engine cools down, the coolant automatically flows back into the cooling system, which ensures that its level is maintained at a constant value.

2. Check the coolant level in the tank regularly, with the car in a strictly horizontal position and the engine turned off. When cold, the coolant level should reach the control mark on the wall/inside the expansion tank, depending on the version. After warming up the engine, the coolant level rises by approximately another 1.0-1.5 cm. If necessary, make the appropriate adjustments - add only the required composition of the liquid (see Specifications).



3. After driving the car for a short time, measure the coolant level again - minor adjustments can be made by adding distilled water, however, it should be remembered that frequent additions of water lead to dilution of the antifreeze, so it is wiser to always add a mixture of the required composition to the system.



4. Regularly arising need to adjust the coolant level indicates the presence of coolant leaks (external or internal), - carefully examine the external condition of the radiator, connecting hoses, filler cap, drain plugs and water pump (see Section Checking the functioning of the cooling system and frost resistance of the coolant, replacing the liquid). If you cannot identify the source of the leak, check the tightness of the expansion tank and radiator caps at a service station.

5. Removing the covers of the cooling system components should be done after the engine has completely cooled down. Wrap the cover in a rag and unscrew it to the first point of weakening resistance - if steam or coolant starts to escape from under the cover, let the engine cool down a little more, and only then remove the cover completely.

6. It is also necessary to check the condition of the coolant, it should be relatively clean. If the liquid has a reddish-brown color, it must be drained, then the cooling system tract must be flushed and filled with a fresh mixture of the required composition. Even if the coolant looks normal, the corrosion inhibitors included in its composition lose their effectiveness over time, so the replacement in any case should be carried out in accordance with Schedule of current maintenance.

7. If necessary, the freeze resistance of the coolant can be checked using a hydrometer - compare the measurement results with the requirements Specifications.

Coolant level check point inside the expansion tank (checked through the neck)

Brake fluid

Warning! When servicing the hydraulic circuit of the brake system, exercise extreme caution. Do not allow brake fluid to come into contact with your eyes, mouth, or painted surfaces of the vehicle! Remember that brake fluid is highly hygroscopic, i.e. it has the property of absorbing moisture contained in the air - never add hydraulic fluid to the brake system that has been stored for a long time in a loosely sealed container! Use only recommended types of brake fluid - mixing different types of fluid may cause the brake system to fail!

1. The brake master cylinder (BMC) is fitted with a reservoir and is installed in the rear left corner of the engine compartment. The driver is warned of a drop in brake fluid level by a warning lamp built into the instrument cluster (see Section Instrument cluster, gauges, control lamps and indicator lights), the float switch of which is built into the cover (models produced before 12.2000)/frame (models produced since 12.2000) gTZ reservoir.

a — Location of the master brake cylinder equipped with a reservoir (1) on models produced up to 12.2000

b — Location of the master brake cylinder equipped with a reservoir (1) on models produced from 12.2000

2. The brake fluid level is checked visually and should be between the "MAX" and "MIN" marks on the translucent walls of the master cylinder reservoir. If necessary, make the appropriate adjustment by adding the required amount of fresh fluid through the reservoir neck - before unscrewing the cap, wipe the reservoir from the outside to prevent dirt from getting into the hydraulic tract.

Note: Do not overfill the tank with liquid.

3. With the cover removed, check the fluid and the walls of the brake master cylinder reservoir for signs of contamination. If rust particles, dirt or water droplets are detected, the fluid should be replaced and the brake system should be bled (see Chapter Brake and auxiliary systems).

4. After completing the adjustment/replacement, check that the tank cap is seated evenly and tightened securely.

5. A gradual decrease in the fluid level in the brake master cylinder reservoir is due to wear of the brake pads. There is no need to add fluid if its level does not fall below the "MIN" mark, - if necessary, check the condition of the friction linings of the brake pads, - replacing the pads will automatically equalize the level.

6. If the need to adjust the brake fluid level arises regularly, you should immediately and thoroughly check the hydraulic tract of the brake system for signs of developing leaks - carefully examine the condition of the calipers/wheel cylinders, the master cylinder, brake pipes, hoses and their nipple connections (see Sections Checking the brake system and Checking the condition and replacing engine compartment hoses, localizing leaks).

7. When the fluid level in the brake master cylinder reservoir drops below the "MIN" mark, the brake system should be "bled" (see Chapter Brake and auxiliary systems).

Power steering fluid

Attention! If the fluid level in the power steering reservoir has dropped below the zone corresponding to the current temperature range, the condition of the power steering mechanism must be checked at a Mercedes-Benz service station - a simple adjustment of the level will not be enough in this case.

Note: As part of the scheduled maintenance procedures, the power steering fluid level is not checked.

1. Checking the power steering fluid level is done at a temperature of about 20°C. The power steering reservoir is equipped with a threaded cap equipped with a measuring probe and is located on the right side of the engine compartment (see illustration Engine compartment of petrol models (using the G55 AMG as an example) and accompanying illustrations). On diesel models, the cylinder head trim panel must be removed to gain access to the power steering reservoir. The fluid level should be between the "MIN" and "MAX" marks on the dipstick blade.

Differential lock hydraulic fluid

Caution! The hydraulic circuit of the differential lock drive uses brake fluid, which must be handled with special precautions (see warning above in the relevant subsection).

Note: As part of the scheduled maintenance procedures, the differential lock hydraulic fluid level is not checked.

1. The location of the differential lock hydraulic reservoir is shown in the illustration Engine compartment of petrol models (using the G55 AMG as an example) and accompanying illustrations.





2. The fluid level should be slightly above the MAX mark on the translucent wall of the tank - if necessary, make the appropriate adjustments, having first checked the hydraulic circuit of the hydraulic drive for signs of developing leaks and having eliminated the causes of the latter.

Transmission fluid (ATF)

Note: The automatic transmissions used in the models of cars under consideration are filled with transmission fluid for their entire service life and do not require regular checking and adjustment of the level.

Checking ATF level

1. It is best to check the ATF level when the engine and transmission are warmed up - perform a short test drive on the car (about 15 km) trip.

2. Park the car on a flat horizontal surface, set the parking brake. To securely fix the car, support the wheels with wheel chocks.

3. Run the engine at idle speed. Depress the foot brake pedal and carefully shift the selector lever from position "P" to position "D" and then return it back. Make sure there are no signs of developing external ATF leaks.

4. The fluid level dipstick is located at the rear of the transmission. Before removing the dipstick, carefully wipe the adjacent surface of the crankcase - dirt cannot get inside the transmission.

5. Using a suitable screwdriver, remove the locking catch (the red tab of the retainer breaks off and the remaining fragment is pushed out of the cover downwards) and remove the lid (see illustration above).

6. Start the engine and, holding the car still with the foot brake, move the selector lever sequentially through all operating ranges, finally returning it to the "P" position.

7. After thoroughly wiping, insert the dipstick all the way into the transmission filler neck. Remove the dipstick and use the length of the wetted section of its blade to determine the ATF level in the transmission housing. When the unit is cold, the level should be between the min and max marks on the lower (25°C) scale of the dipstick; when hot, between the identical marks on the upper (80°) scale (see illustration above).

8. During a short trip, warm up the transmission to normal operating temperature, wait about 2 minutes and check the fluid level again with the engine running. If the ATF level is excessively high, excess fluid must be pumped out of the AT housing without fail - an excess of the level, as well as a lack of ATF, can lead to transmission failure.

9. Replace the filler cap and secure it with the new locking clip (see illustration above).

10. Carefully inspect the AT crankcase for signs of developing leaks, and make the necessary corrections if necessary.

Transfer case lubricating fluid

Note: As part of the scheduled maintenance procedures, the oil level in the transfer case is not checked.

1. Make sure the vehicle is level. Wipe the surface of the transfer case around the filler/inspection plug (see accompanying illustration - 750.65 Series Transfer Case Filler/Inspection Plug Location).



2. Unscrew the plug and, inserting a finger into the hole, check the oil level in the crankcase - it should reach exactly to the lower edge of the hole. If necessary, make the appropriate adjustments.

Windscreen/Headlight Washer Fluid

Warning! Windscreen washer concentrate is highly flammable! When handling windscreen washer concentrate, the use of fire, open flame and smoking are prohibited.

1. The windshield washer fluid reservoir is located in the right rear corner of the engine compartment, behind the coolant expansion tank and is equipped with a filler neck with a bayonet-type cap (see accompanying illustration - Location of the windshield/headlamp washer fluid reservoir in the engine compartment (for all models)). The capacity of the tank is about 7.5 liters (see Specifications).



2. The driver is warned of a drop in the fluid level by the activation of a control lamp built into the instrument cluster - the control lamp switch sensor is mounted in the upper part of the washer fluid reservoir.

3. In areas with a moderate climate, the system can be filled with ordinary water, but it is recommended to add glass cleaning products to the water (summer concentrate MV has the S marking). The reservoir should be no more than two-thirds full to allow for expansion of the water when it freezes. In cold climates, a special glass cleaner concentrate should be used (w marking), which lowers the freezing point of liquids, which can be purchased at any car accessory store. It is usually sold in concentrated or ready-made form. Mixing the concentrate with water should be done strictly in accordance with the instructions on the packaging of the manufacturer of the product.

Attention! Never use antifreeze from the cooling system to wash the glass, as it can damage the paintwork if it gets on the body panels!