105687-0281 ZEXEL 9 420 615 720 BOSCH AUTOM. ADVANCE MECHANISM 9420615720 1056870281 1157403920

COMPRESSION PRESSURE MEASUREMENT
1. Inspection Check to make sure -(1) The crankcase oil level is correct, and the air cleaner, starter and battery are all in normal condition.(2) The engine is at the normal operating temperature.2. Measurement (1) Move the control lever to a position for shutting off fuel supply.(2) Remove all glow plugs from the engine. Install the compression gauge and adapter (ST332270) combination to a cylinder on which the compression pressure is to be measured.
Compression gauge and adaptor
Measuring compression pressure(3) Turn the engine with the starter and read the gauge pressure at the instant the gauge pointer comes to stop.(4) If the gauge reading is below the limit, overhaul the engine.
a) Be sure to measure the compression pressure on all cylinders.b) The compression pressure varies with change of engine rpm. This makes it necessary to check engine rpm at the time of measuring the compression pressure.
a) It is important to measure the compression pressure at regular intervals to obtain the data on the gradual change of the compression pressure.b) The compression pressure would be slightly higher than the standard in a new or overhauled engine owing to break-in of the piston rings, valve seats, etc. It drops as the engine components wear down.
TROUBLESHOOTING
1. GeneralThe diagnosis of troubles, especially those caused by a faulty fuel injection pump or injection nozzles, or low compression pressure, can be difficult. It requires a careful inspection to determine not which item is the cause, but how many causes are contributing to the cause. Several causes may be contributing to a single trouble.On the following pages, there are troubleshooting charts on which engine troubles can be traced to their causes. Each chart has items to be verified ahead and suggested inspection procedure.Diesel engines exhibit some marked characteristics during operation. Knowing these characteristics will help minimize time lost in tracing engine troubles to their source. Following are the characteristics of diesel engines you should know about for diagnosis:* Combustion know (diesel knock)* Some black exhaust smoke (when the engine picks up load)* Vibration (due to high compression pressure and high torque)* Hunting (when the engine speed is quickly decreased)* Some white exhaust smoke (when the engine is cold, or shortly after the engine has been started) 2. Engine troubleshooting Problem 1: Hard starting(1) Items to be checked for ahead* Clogged air cleaner* Wrong oil grade for weather conditions * Poor quality fuel* Low cranking speed(2) Inspection procedure Problem 2: Fuel knockMore or less fuel knock occurs in diesel engines. This may be caused either by an excessively large delay period or by a too fast rate of fuel injection.(1) Items to be checked for ahead* Clogged air cleaner* Poor quality fuel(2) Inspection procedure Problem 3: Overheating(1) Items to be checked for aheadOverheating might also be caused by abnormal operating conditions. If the engine is overheating but its cooling system is not contributing to this trouble, it is necessary to check the difference between the ambient temperature and coolant temperature when the engine is in