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Service process of Mercedes-Benz CLS-350 CGIOverviewThe basic service package consists of the following processes:Engine oil changeOil filter changeAir filter clean/replaceAc filter clean/replaceBattery testFront and rear disc thickness checkFront and rear break pad checkBrake fluid change (Brake bleeding)MiscellaneousEngine oil changeSuction of oilThe car engine is switched on. The engine is kept running in idle till a temperature of 80C is obtained inside engine. (appx 8 mins)This heats the engine oil and lowers its viscosity such that oil can be extracted easily.To extract the oil, a pneumatic oil extractor is used. (1.1)The hose is inserted in the dipstick tube (1.2), while pneumatic vaccum pressure extracts oil (8.5 litres) from the engine. (appx 12 minutes)

(1.1) Pneumatic oil extractor(1.2) Hose inserted in the dipstick tubeOil filter replacement

Tools required: Filter cap (28Nm) ( fig 2.1)Ratchet (long)27 size hex Box

Procedure (fig 2.2)Fit the filter cap on filter headUse 27 size hex box to grip the filter capSocket the ratchet on the hex box.Set the ratchet to turn anti-clockwise.Loosen the oil filter completely and allow it to stay for 2 minutes.This is done to drain some quantity of oil from the filter.

(2.1) Oil filter cap(2.2) Removal of oil filterOil filter replacement

Procedure:After 2 minutes, remove the oil filter assembly.Care to be taken so as to not let drops of oil drip on hands as it is hot.extract the oil filter from the filter head.Old oil filterThis is how the old oil filter looks.Purifying engine oil from contaminants such as specks of dirt and metal powder clogs the filter as is evident from the colourThus an oil filter protects the engine from floating garbage, which would other wise damage the engine.Oil filter replacement

Procedure:New oil filter is fitted in filter head as shown. (fig 3.1)New O rings are carefully fitted in respective grooves.The filter assembly is refitted In its place using filter cap, ratchet and 27 size hex box.The filter head is tightened to a torque of 28Nm

(3.2) New oil filter fitted in filter head(3.3) Filter assembly tightened

(3.1) Oil filter elementEngine oil change

The oil grade used for Mercedes 272 petrol engines is 0W40.8.5 litres of mobile 1/Mercedes oil brand is poured inside the engine oil entrance.Care should be taken that oil is not spilled else where.Oil cap is fixed back on completion of pouring

Hazard warning!The engine should not be started before the oil has be poured completely, as doing so may result in engine seize, resulting from the heavy damage caused to engine

(4.1), (4.2) 8 litres of 0W40 oil grade poured into engine Air filter

(5.1) Opening Air filter box

(5.2) Air filter element along with housingThe CLS 350 petrol engine W272 comes with two air filters housed in the engine cover(removable), each of them breathing air into 3 individual cylinders, forming a total of 6 cylinders or V6A 25mm size tox driver is used to open 4 screws on each oh the housing. (fig 5.1)Depending on the condition of the filter, it is either cleaned or replaced.

(5.3) Dust particles contaminate Air filterAc filter

PurposeAc filter or cabin air filter purify the air coming inside the seating cabin through heating, ventilation or air conditioning from dust or pollen.

Tool required20mm tox is required to open 4 screws to slip out the Ac filter on the front left side of engine, behind the glove box.

ProcessThe filter is examined visually to determine if it can be cleaned or replacedUsually the Air filter and Ac filter are cleaned together in the service process as shown in the fig 6.2, by a pneumatic high pressure pipe.

(6.1) Ac filter

(6.2) cleaning of Air , Ac filterBrake pads Inspection

(7.1) Removal of wheels(7.2)Break pads, caliper and discProcessIn order to examine brake pads, the wheels are to be removed first (fig 7.1).Break pads inside caliper assembly has to be visually inspected for wear (fig 7.2).

ToolsA pneumatic gun coupled to a 17 mm hex box is used to open 5 bolts of wheel.Pneumatic air flow of 300l/min is sufficient to open the tightest bolts.

CautionThe pneumatic gun must be checked to see if it has been set to anti-clockwise turning only.

Brake pad wear

Mercedes Benz standard calculationFront Brake Pad

1mm thickness = 6000kmsMinimum thickness required = 2mmThickness by inspection = 5mm (appx)Brake pad life = (5-2)6000 = 18,000kmsRear Brake pad

1mm thickness = 6500kmsMinimum thickness required = 2mmThickness by inspection = 6mm (appx)Brake pad life = (6-2) 6500 = 26,000kms(8.1) Front LH Brake pad (appx 5mm)Disc Plate wear

ProcessThe front and Rear Disc plate are subject to wear due to friction between brake pads and the plate.The Disc thickness is measured to determine if it has to be replaced.

Tools required Standard vernier caliper

Mercedes Benz Standard values: Disc PositionMin RequiredActual value ResultFront Discs(LH,RH)29.4mm29.2mmChange!Rear Discs(LH,RH)19.4mm19.6mmOk!Break fluid change

ProcessTo replace brake fluid, an electric bleeder machine is used as shown in fig 10.1.The hose of bleeder is connected to the Brake fluid box. 3 litre of brake oil is poured in bleeder.Pressure is set a little more than 2 bar as shown in fig 10.2. This pressure acts from the brake fluid box and throught the circuit till the calipersThe brake bleeding process is carried from the farthest to nearest caliper in circuit from fluid box.for Eg: since the brake fluid box is located near Front RH, bleeding process is started from Rear LH > Rear RH > Front LH > Front RH

(10.1) Brake bleeder machine(10.2) Pressure of minimum 2 bar is setBrake bleeding process

Tools required11mm Ring spannerFlexible tube of 1mContainer

ProcessFix one end of the pipe to a container and other end to the bleeding nozzle of caliper.Use 11 mm ring spanner to turn nozzle anti-clockwise such that it loosensLoosen in to an extent where sufficient quantity of Brake fluid is bleeding from caliper to container.Collect 600ml of fluid from each of the rear calipersCollect 900ml fluid from each of the front calipersSufficiently tighten nozzle back.(11.1) Bleeding processOther Miscellaneous activities

Under Body Damage CheckVisual inspection revealed damage to Oil sump Case and cracks to front Bumper.Battery Inspection (starter battery) (fail)Mid-tronics setup is used to measure battery charge. The battery was charged. ChargeSpecific gravityMin capacityResultMin Reqd12.0V1.19050Ah -Actual12.39V1.22512AhChargeTyre Groove depth Test (pass)Depth of grooves are measured by depth gaugeFront LHFront RHRear LHRear RHMin Reqd6mm6mm5mm5mmActual7.2mm7.4mm6.8mm6.8mm (12.1) (12.2)(12.3)Other miscellaneous activities

Star testA wireless multiplexer is connect to the car which records data from 38 different sensor heads and shows the recordings on a screenIf a sensor is malfunctioning, the Result in front of the sensor will show a fault code FThe technician can thus use Star test as a tool for diagnosis of problems.In case a Fault code is shown, customer approval is taken to do the necessary repairs.

ReferrencesThankyou.