MAN B&W L23/30H working cards
Four-stroke auxiliary diesel engine (generating set)
The complete set of working cards for the MAN B&W L23/30H generating sets: each card lists safety precautions, starting position, manpower and time, special tools, spare parts and the step-by-step job. Covered are cylinder head dismantling and mounting, valves and seats, valve clearance, fuel injection valve and pump, Pmax adjustment, piston and connecting rod, liner honing and replacement, main and big-end bearing inspection and replacement criteria, camshaft, autolog crankshaft deflection, hydraulic tools, lube oil and cooling water components, starting system, turbocharger water washing, charge air cooler, overspeed trip and alarm tests, crankcase relief valves and resilient mountings.
Maintenance procedures
Adjusting inlet and exhaust valve clearance
- Stop the engine, shut off starting air, fuel, cooling water and lube oil; remove rocker covers; open all indicator valves. p. 53
- Turn the engine so the roller rests on the base circle of the cam (both valves closed). p. 54
- Loosen the adjusting screws on the valve bridge and rocker arm. p. 54
- Put the 0.50 mm 'correct' feeler gauge over the spindle nearest the rocker bracket and set it with the rocker-arm screw; lock. p. 54
- Put a second gauge over the other spindle and set it with the valve-bridge screw; lock. p. 54
- Repeat for the exhaust valves with the 0.90 mm gauge; check the 'incorrect' gauges do not enter. p. 55
Overhauling a fuel injection valve
- Remove the valve with the special tool and clamp it in bracket VTO-W020 on the test pump; loosen the lock nut and unload the spring. p. 85
- Clean carbon off the nozzle tip, remove the nozzle nut and nozzle without damaging lapped faces. p. 85
- Clean all parts in kerosene/gas oil with a hard (not steel) brush; clear nozzle holes with the special drill; flush cooling ducts and blow dry. p. 85
- Check the needle slides down by its own weight; scrap nozzles with oval-worn holes. p. 86
- Reassemble with new sealing rings, antiseize on the nozzle shoulder, torque the nozzle nut to 100–120 Nm. p. 86
- Pressure test and set opening pressure to 320 bar. p. 86
- Clean and if needed grind the valve sleeve seat, fit with antiseize, fit HP pipe, then tighten the nuts with a torque spanner. p. 87
Dismantling a cylinder head
- Drain cooling water via drain and vent cocks. p. 67
- Remove top cover and pump front cover; disconnect HP fuel pipe, rocker lube pipe, cooling water outlet branch and exhaust flange screws. p. 67
- Remove the cylinder head nuts with the hydraulic jacks (card 520-01.05). p. 67
- Fit the lifting tool on the fuel valve studs with the distance pieces and lift the head away. p. 67
Technical specifications
| Valve clearance | inlet 0.50 mm, exhaust 0.90 mm with 'correct/incorrect' feeler gauges | p. 54 |
|---|---|---|
| Valve clearance job | 1/4 hour, 1 man | p. 53 |
| Fuel injection valve overhaul | 2 hours, 1 man; opening pressure 320 bar | p. 84 |
| Cylinder head dismantling | 1 hour, 2 men; nuts removed with hydraulic jacks | p. 66 |
Source: manufacturer's manual “MAN L23-30H maintenance instructions (working cards)”, 229 pages. Page numbers refer to the original. Check against the manual on board before work.