Foreword These instructions are intended to help perform repairs properly on the engine described here. The illustrations and associated descriptions are typical for the current state of development. Please note that all work in these repair instructions was performed with the engine removed. The expert technical knowledge required for handling gas engines has been assumed in creation of this publication. Repairs to drive units are to be performed by our customer service or the customer service of the manufacturer.
Best regards MAN Nutzfahrzeuge Aktiengesellschaft Nuremberg Plant
Since our products are in continuous development, we reserve the right to make technical modifications.  2002 MAN Nutzfahrzeuge Aktiengesellschaft Reprint, duplication or translation, as a whole or in part without the written approval of MAN is prohibited. MAN reserves all rights accorded by the relevant laws on copyright. MTDA
Technical status: 04.2002
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51.99598-8059
Contents
Page Engine type classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Fault table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 General notes on engine overhaul . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 llustrations of E 2876 E 302 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Engine lubrication schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Cooling system schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Engine management schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Ignition Replacing the spark plugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Cooling system Draining and filling coolant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Lubrication Removing and installing the oil cooler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Removing and installing the oil pump, servicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Oil injection nozzle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Flywheel / crankshaft seal Removing and fitting vibration damper, replacing front crankshaft gasket . . . . . . . . . . . . . . . . . . . . . . . . Removing and installing the flywheel, replacing the starter motor toothed wheel . . . . . . . . . . . . . . . . . . Removing and installing the crankshaft gasket on flywheel side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Replacing the bearing race . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Crankshaft gaskets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29 33 35 36 37
Intake / exhaust system Removing and installing the intake pipes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Removing and installing the exhaust pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Cylinder head Removing and installing the cylinder head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Setting the valve clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dismantling and assembling the rocker arm mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Removing and installing valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Check compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
40 45 46 47 50
Valve timing Removing and installing the gear case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Removing and installing the camshaft, replacing camshaft bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Checking the valve timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Crankgear, pistons Removing and installing the crankshaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Removing and installing pistons with conrods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Removing pistons from conrod and fitting, checking – replacing conrod . . . . . . . . . . . . . . . . . . . . . . . . . Removing and installing piston rings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Replacing cylinder liners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Measuring piston retrusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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55 58 61 63 65 69
Contents
Attachments Removing and installing the starter motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 Service Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Special tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
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Engine type classification
The type designation, consisting of a sequence of letters and numbers, indicates some characteristics of each engine, provided you are familiar with the basic terminology. The system is explained here using the type E 2876 E 302 as an example: E
The “E” at the start of the type designation stands for natural gas (German: Erdgas)
28
The numbers “28” indicate that this is a power unit with 128 mm bore
7
The “7” means 170 mm stroke This figure is, however, only approximate for this model. The actual stroke is 166 mm.
6
The “6” indicates the number of cylinders 6
E
The “E” stands for “fitted engine” (German: Einbaumotor) and is intended to distinguish MAN vehicle engines
302
This is a factory–internal development number.
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Safety instructions
General This brief overview summarises important instructions and is structured into areas of main concern in order to impart the knowledge necessary to prevent accidents involving injury to persons, damage to the engine or other property and harm to the environment. Additional notes are included in the operator’s manual for the engine. Important: Should an accident occur despite all precautionary measures, particularly one involving contact with corrosive acid, penetration of fuel under the skin, scalding by hot oil, antifreeze splashing into the eyes etc. you must seek medical assistance immediately.
1. Regulations for the prevention of accidents with personal injury
Inspection, adjustment and repair work may only be performed by authorised and skilled personnel. D The engine may only be started and operated by authorised personnel. D Wenn der Motor läuft, nicht zu nahe an drehende Teile kommen. Wear tight–fitting work clothes.
D Do not touch hot engine with bare hands: risk of burning yourself.
ËË D Keep engine vicinity, ladder and steps free of oil and grease. Accidents resulting from slipping may have serious consequences. D Work only with tools that are in good condition. Worn spanners slip: risk of injuries. D Persons must not stand under an engine suspended from a crane hook. Keep lifting gear in good order.
D Open coolant circuit only after the engine has cooled down. If it is unavoidable that the circuit be opened with the engine at operating temperature, observe the instructions in the chapter “Maintenance and care” in the operating instructions. D Neither retighten nor open pressurised pipelines and hoses (lube oil circuit, coolant circuit and downstream hydraulic oil circuit if fitted): risk of injuries resulting from emerging fluids.
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Safety instructions
D When working on the electrical system, first disconnect the earth cable of the battery and reconnect this last to prevent short circuits.
D Observe manufacturer’s instructions for handling batteries. Caution: Battery acid is toxic and caustic. Battery gases are explosive.
D When performing welding work, observe the “Notes for welders”.
2. Regulations for the prevention of engine damage and premature wear
D The engine must be cleaned thoroughly prior to repair. Ensure that during repair work no dirt, sand or foreign bodies enter the engine. D If engine operation is disrupted, immediately determine the cause and have it remedied to prevent additional damage. D In every case, use only original MAN spare parts. The installation of parts that are “just as good” not originating from MAN can under certain circumstances cause severe damage – for which the workshop performing the repair must bear responsibility. D Never allow the engine to run dry, i.e. without lubricant or coolant. Appropriate notices must be attached to engines that are not ready for operation. D Only use lubricants, fluids and fuel approved by MAN (gas, engine oil, antifreeze and corrosion protection agents). Ensure cleanliness at all times. D Do not fill engine oil beyond the max. notch on the dipstick. Do not exceed the maximum permitted operating inclination of the engine. Nonobservance can lead to severe engine damage. D Control and monitoring devices (charge control, oil pressure, coolant temperature) must be in perfect working order.
3. Safety instructions for handling the ignition system
D When the engine is in operation, the following parts of the ignition system must not be touched or disconnected under any circumstances: – ignition coils and caps – cables of the high-voltage circuit – cables of the low-voltage circuit – connectors of the output and input wiring harness D For all work related to set–up, operation, conversion, customisation, maintenance and repairs, the power must be disconnected from the ignition system and secured against inadvertent reactivation.
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Safety instructions
4. Regulations for the prevention of environmental damage
Engine oil and filter cartridges D Old oil must be passed on for recycling. D Take extreme care that no oil enters the waste water system or seeps into the ground. Caution: Gefahr der Trinkwasserverseuchung! D Treat used filter inserts and cartridges as hazardous waste. Coolant D Treat undiluted corrosion protection agents and / or antifreeze as hazardous waste. D When disposing of used coolant, the regulations issued by the relevant local authorities must be observed.
5. Instructions for handling used engine oil ∗ Prolonged or repeated skin contact with any type of engine oil draws grease from your skin. This can lead to dryness, irritation or skin inflammation. Used engine oil also contains hazardous substances that have caused skin cancer in tests on animals. If the basic principles of work safety and hygiene are observed, handling used engine oil does not represent a health hazard. Precautionary measures to protect your health: D Avoid prolonged, repeated skin contact with used engine oil. D Protect your skin with suitable skin protection cream or protective gloves. D Clean any skin that comes into contact with engine oil. – Wash thoroughly with soap and water. A nail brush provides effective assistance here. – Special hand cleaning agents make it easier to clean dirty hands. – Do not use petrol (gasoline), diesel fuel, gas oil or solvents as washing agents. D After cleaning, apply skin cream containing fat. D Change clothing and shoes that are soaked in oil. D Do no put oily cloths in you pockets. Ensure that used engine oil is disposed of in the appropriate manner. – Engine oil is a substance that endangers the water supply – for this reason, do not pour engine oil on the ground, in lakes or rivers, down plugholes or in the waste water system. Violations of this regulation are punishable offences. Carefully collect and dispose of used engine oil. Information on collection points can be obtained from sales personnel, the supplier or the local authorities. ∗ Based on “Information sheet for handling used engine oil”.
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Safety instructions
6. Safety instructions for handling gaseous fuels
Gaseous fuels consist essentially of methane, propane and butane as well as traces of higher hydrocarbons and inert components such as carbon dioxide and nitrogen.
D The regulations applicable to gas installations must be observed.
D Exhaust gases are toxic. Comply with the regulations for the installation of MAN industrial gas engines for operation in enclosed areas. Ensure adequate ventilation. D Smoking and naked flames are prohibited.
D Leaks in the gas supply system mean danger of explosion and these must be remedied immediately.
D Fire extinguishers and other firefighting equipment must be on hand. D Do not store combustible material in the engine room.
Conduct in the case of gas leaks D Close the shutoff valve of the gas supply. D Switch off the main switch of the electric system. D Cordon off the danger zone. Ask uninvolved persons to leave the danger zone. D If gas is leaking, inform the relevant authorities immediately and initiate repairs. Conduct in the event of fire D Alert the fire brigade. D Immediately assist any injured persons, call paramedics if necessary. D In the case of a pure gas fire, do not extinguish the gas flame; if necessary, cool down the burning object (e.g. by starving the fire of oxygen: close doors and windows). Burning gas = controlled gas! D Prevent the flames from spreading. D If the flames spread to the surroundings, use a fire extinguisher. D Stay calm!
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Fault table
Operating faults and possible causes
We recommend A repair is only complete when both the damage that occurred and the possible causes have been eliminated. Finding out the cause of damage is often more difficult than repairing the damage that occurred. We therefore recommend that you obtain a precise description of the operating fault before removing and dismantling components. Then use a process elimination (questions) to pinpoint the probable causes and investigate and eliminate these successively on the basis of the table and your own experience. This helps to reduce repairs to the required scale and to counteract claims regarding “overeager” replacement of parts and complaints about expensive work and down time.
Note: The following list is conceived as an aid to memory for experts so that to causes of damage are overlooked when dealing with faults. It is expected of experts that they are very familiar with the repair instructions for the engine, but also with the engine operating instructions and “Fluids and lubricants for MAN–industrial gas engines”.
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Fault table
1. 2.
x
Starter motor does not turn engine or only slowly (solenoid switch energises (“click” is audible) Starter motor turns, engine does not turn 3. Starter motor turns engine, engine does not start / starts poorly 4. Ignition failure 5. . Irregular engine running 6. Engine stalls during operation, no longer starts 7. Engine “shakes” 8. Engine only runs at idle speed 9. Idle speed unstable 10. Engine does not reach its nominal speed 11. Engine does not reach its nominal power 12. Fuel consumption too high 13. Oil consumption too high 14. Engine too ”loud” / mechanical noise 15. Heavy blue smoke formation 16. Heavy white smoke formation 17. Exhaust temperature / exhaust back pressure too high (thermal overload) 18. Lubricating oil pressure too low 19. Temperature difference engine exit / engine entry too great 20. Coolant temperature too high Possible causes Batteries discharged, battery cable connections loose or corroded, power circuit interrupted
x x x x
x x x x x x x x x o
x x x o
x x x
x
x x x x x
x
Throttle valve not in full–load position / actuating rod jammed / throttle valve incorrectly adjusted
x x x x x x x x x
x x
x
x x
x x
x x
x x
x
x x x x x x x x x x x x x x x x x x x
x x x x x x
x = o =
Starter motor defective (carbon brushes loosened / worn, coil damaged, ground fault) Engaging lever / bearing bolt of the engaging lever broken Crankshaft drive blocked Engine oil viscosity unsuitable, not suited to ambient temperature Ignition control unit defective Impulse sensor defective / gap incorrectly set Spark plug defective Ignition cable defective Ignition coil defective Ignition point incorrectly set Throttle valve does not open / actuating rod jammed / setting unit de–energized or defective
Shut–off solenoid valve of gas supply closed / does not open Zero pressure regulator of gas supply not correctly set or defective Gas metering valve defective Gas / air mixture too rich or too lean Lack of compression, or more than 3 bar pressure difference between the individual cylinders Valve clearance not correct Valve guides heavily worn Valve seats leaking Piston rings heavily worn, broken (overpressure in the crankcase) Air filter heavily soiled Charge mixture cooler soiled / leaking Charge mixture piping leaking Turbine and compressor wheel in the turbocharger soiled (running off balance) Coolant entering combustion chamber (cylinder head gasket leaking) Engine in cold running phase Crankcase breather blocked Oil level in sump too high Safety valve in oil circuit faulty (does not close, spring fatigued or broken) Bearing wear Oil pump heavily worn Safety valve in the oil circuit defective (does not open), oil lines / oil ducts blocked Unsuitable exhaust–gas piping, heat exchanger and catalytic converters with excessive resistance
Probable Possible
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Fault table
1. 2.
x = o =
Starter motor does not turn engine or only slowly (solenoid switch energises (“click” is audible) Starter motor turns, engine does not turn 3. Starter motor turns engine, engine does not start / starts poorly 4. Ignition failure 5. . Irregular engine running 6. Engine stalls during operation, no longer starts 7. Engine “shakes” 8. Engine only runs at idle speed 9. Idle speed unstable 10. Engine does not reach its nominal speed 11. Engine does not reach its nominal power 12. Fuel consumption too high 13. Oil consumption too high 14. Engine too ”loud” / mechanical noise 15. Heavy blue smoke formation 16. Heavy white smoke formation 17. Exhaust temperature / exhaust back pressure too high (thermal overload) 18. Lubricating oil pressure too low 19. Temperature difference engine exit / engine entry too great 20. Coolant temperature too high Possible causes x Flow resistance of cooling system too great x x Soiling of cooling system x Coolant level too low, air in coolant circuit x Water pump configured too small x x Coolant lines leaking, clogged or twisted x Engine mounting unsuitable / worn
Probable Possible
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General notes on engine overhaul
The service life of an engine is influenced by very different factors. It is therefore not possible to specify certain fixed numbers of operating hours for general overhauls. In our view, it is not necessary to open up and engine or perform a general overhaul as long as the engine has good compression values and the following operating values have not changed significantly in relation to the values measured on commissioning the engine: D Exhaust temperature D Coolant and lubricant temperature D Oil pressure and oil consumption The following criteria greatly influence the length of the engine service life: D Correct power setting in accordance with conditions of use D Technically correct installation D Inspection if installation by authorised personnel D Selection and quality of lubricants, gas and coolant according to publication “Fluids and lubricants for MAN Gas Engines�
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llustrations of E 2876 E 302 engine
Illustrations of engine E 2876 E 302
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Engine lubrication schedule
7 6 8
5
1
2
3
4
1 Oil suction pipe 2 Distributor pipe
5 Oil pressure relief valve 6 Bypass valve
3 Oil spray nozzle 4 Oil pump
7 Oil filter 8 Oil cooler
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Cooling system schedule
Cooling system with membrane expansion tank
4 5
3
6 7
2 8 3 9 10 1
1 2 3 4 5 6 7 8 9 10
Engine Bleeder line ∅ 10 mm, flow rate 7 l/min to max. 10 l/min Bleeder reservoir Automatic breather valve Sensor for liquid level Plate with 5x10 mm bore Diaphragm expansion vessel (0,6 bar) Connection line to the intake side of the coolant pump ∅25 mm Coolant inlet Coolant outlet
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Cooling system schedule
D Pressure relief-- savety valve 3,5 bar Operating pressure:min. 0,6 bar max. 3,0 bar D Observe the filling regulations of the manufacturer of the cogeneration power unit. D Coolant filling capacity, see “Service Data� D Fill up the cooling system with the filler device, keeping the breathers open until the coolant emerges bubble--free D Close breathers and increase pressure to a value which is approx. 0,2--0,4 bar above the pre--pressure of the expansion vessel D Start up system. Let it cool down after trail operation (i.e. after it reaches the operating temperature) D When the cooling temperature has fallen to below 50_C, increase the system pressure to 0,5 bar above the pre--pressure of the expansion vessel via the filler device
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Cooling system schedule
Cooling system in semi-- open system
3
4 2
5
6 7
1
1 2 3 4 5 6 7
Engine Bleeder line ∅ 10 mm, flow rate 7 l/min to max. 10 l/min Filler cap with over--/ underpressure Expansion tank Connection line to the intake side of the coolant pump ∅25 mm Coolant inlet Coolant outlet
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