This aspect plays a very important role in day to day working of a technician. It becomes so mandatory to diagnose a fault before we proceed for its rectification. A qualified technician proceeds systematically with a lot of patient in order to detect the fault. We must adopt all our technical skill and talent so that the faults can be rectified within a stipulated time within the available resources and time.
ENGINE NOT CRANKING WITH SELF STARTER
|Defective Ignition Switch||Check up for loose connection|
|Defective Solenoid||Check the self-starter by giving direct current|
|Loose or dirty battery connection||Clean and fix the connection properly|
|Hydraulic Lock in combustion chamber||Remove the spark plug crank the engine and observe the engine oil or water comes out from the spark plug hole if so change the cylinder head gasket|
|Jamming of self-starter pinion with ring gear||Demount the self-starter, clean the starter pinion and refit.|
POOR STARTING OF THE ENGINE
|Weak spark||Check up and adjust air gap of spark plug and distributor|
|Loose connection in primary circuit||Check up all connections for proper tightness|
|Defective Solenoid||Replace with the new one|
|Restricted or defective fuel supply||Check up working of fuel pump and carburetor|
|Restricted Air supply||Clean air cleaner and check up choke valve position|
SPARK MISSING IN ENGINE AT ALL SPEEDS
|One or more spark plugs short||Replace the defective plugs|
|Loose or dirty wiring connections||Set them correctly|
|Presence of water in petrol||Drain the petrol, remove water traces and refill petrol|
|Maladjustment of float ball level||Set it correctly|
|Wrong Adjustment of Carburetor||Adjust slow running perfectly|
HIGH FUEL CONSUMPTION
|Mis-adjustment of contact breaker points||Adjust these properly|
|Defective spark plug||Adjust the air gap properly or change the spark plug|
|Ignition timing set too advance or too retard||Set the ignition correctly|
|Binding of brakes||Adjust the brakes correctly|
|Clutch slipping||Adjust clutch plate correctly|
EXCESSIVE OIL CONSUMPTION
|External leaks||Change oil seals and Replace gaskets|
|Burning oil in the combustion chamber||Check valve stem and piston ring clearance|
|Oil level too high||Maintain oil at proper level|
|Poor viscosity of oil||Use correct grade oil|
ENGINE STOPS IMMEDIATELY AFTER START
|Defective air gap of spark plug||Set it correctly|
|Dirty spark plug||Clean it and test properly|
|Dirty or misadjusted CB point||Clean and adjust|
ENGINE OVER HEATING
(a) Loose or broken fan belt.
(b) Leaks in cooling system.
(c) Restricted water passage.
(d) Dirty Coolant.
(e) Radiator air passages blocked.
(f) Defective water pump or impeller.
(g) Defective thermostat
LOW OIL PRESSURE
|Diluted or thin oil||Change oil|
|Oil pump screen clogged||Clean screen|
|Worn pump gear||Overhaul pump|
|Main and big end bearings badly worn||Replace bearings|
|Defective gaskets||Replace gasket|
|Weak relief valve spring||Change the spring|
|Leak in the system||Trace and rectify|
|Engine over heating||Trace and rectify|
|Pressure gauge unserviceable||Rectify|
HIGH ENGINE OIL PRESSURE
|Oil too thick (wrong grade)||Fill correct grade|
|Choked passage to relief valve||Rectify|
|Relief valve set too high||Set Correctly|
|Pressure gauge over-reading||Test with Master Gauge|
OIL MIXING WITH WATER
|Oil cooler tubes punctured||Replace the tube assembly|
|Cylinder head gasket cracked||Replace the gasket|
|Cylinder head or block cracked||Repair or Replace|
ROAD TEST OF THE VEHICLE
The vehicles should be road tested after over hauling. First start the vehicle and observe the engine sound, any leak (oil, fuel and water) and all the gauges with safety warning provided on instrument panel. If gauges read satisfactory then go for road test. After setting the vehicle in motion first check the foot and hand brake serviceability, then run the vehicle in different gears and apply the brakes as and when required. At the end of the road test again check the wheel drum of the vehicle for overheating and any leak from the engine.