Engine Technology Engine Diagnostic its requires an understanding of the fundamentals & a systematic approach to determine what the problem is. If the engine indicates problem, it must be tested to find source of the problem If engine has a problem, other system also cannot function properly Introduction several primary test that conducted to determine engine condition: 1.Engine / cylinder compression test – measure amount of pressure that produces during compression stroke. 2. Engine / cylinder leakage test – measure how well cylinder / combustion chamber are sealed. 3. Cylinder power balanced – check the efficiency of individual cylinder. 4. Engine oil pressure test – determine wear of other engine parts such as bearing oil pump and etc. 5. ECU fault reading – using ECU scanning tools to read faulty of sensors and actuators

Engine Technology Engine Diagnostic related tools that used to diagnose engine faults: 1. Cylinder compression tester 2. Cylinder leakage tester 3. Exhaust gas analyzer 4. Engine analyzer 5. Tachometer 6. Dwellmeter 7. Service bay diagnostic computer (ECU Scanner) 8. Dynamometer Engine/Cylinder Compression test How well a cylinder develops the pressure is an indication of the condition of piston, piston rings, cylinder walls, valves and head gasket Engine compression readings are considered normal if the lowest reading is 75% or more of the highest

Engine Technology Engine Diagnostic Two types of cylinder compression test: 1. Dry test – normal compression test 2. Wet test – engine oil (15cc) is added into cylinder through spark plug holes to help locate the leak After wet test, if the readings increase to a more normal value, it’s indicated: 1. The worn / fault of piston 2. Piston rings 3. Cylinder wall

Engine Technology Engine Diagnostic Engine/Cylinder Leakage test check the leakage of engine parts in different way by applying compressed air into cylinder in compression stroke and only little air should escape from the cylinder if the engine in good condition location of leakage can be found by listening and feeling around the various parts of the engine. latest cylinder leakage tester can calculate percentage of leakage, where 0% means no leaking and 100% mean cylinder cannot hold any pressure. If reading is same, fault may came from the valve assembly & head gasket: 1. broken of valve spring – cause valve sticking 2. incorrect valve adjustment – valve open to short or not seating 3. sticking valves – not seating 4. worn or burn of valves and valves seat – valve not seating 5. worn of camshaft or lifter – incorrect valve operation (open to short) 6. blown head gasket – pressure goes to the other cylinder or water jackets

Engine Technology Engine Diagnostic

Engine Technology Engine Diagnostic Cylinder Power Balance to see if engine's cylinders are producing the same amount of power. Ideally, all cylinders produce the same amount to minimize lost of power by keeping the engine running and allows the engine to run smoothly cylinders are shorted out one at a time and the change in engine speed is recorded. Ideally, the changes in engine rpm should be about equal as each cylinder is shorted out Unequal power mean a problem in the cylinders themselves, as well as the rings, valves, intake manifold, head gasket, fuel system, or ignition system Oil Pressure Test to determine wear on the engine's parts. Excessive clearances, often the result of wear, between a shaft and its bearings will have an affect on oil pressure. The pressure of the oil depends upon the efficiency of the oil pump and the clearances through which it travels

Engine Technology Engine Diagnostic Other Engine Test Engine vacuum test – to measure the intake manifold vacuum during engine running (low & high RPM) Exhaust back pressure test – to measure amount of exhaust gas backpressure. If the reading exceeds specification (1.25 psi) it indicates a restricted exhaust system. Exhaust gas analyzer – measure amount of engine pollutant and air fuel mixture (rich or lean). Engine analyzer test – check engine ignition primary, secondary & ignition timing ECU scanner – to read faulty of electronic component and do the actuator test for EFI, ABS and etc. Dynamometer – measure engine power and vehicle speed under various operating conditions.

Engine Technology Engine Diagnostic Once the compression, cylinder leakage, vacuum, and power balance tests are performed, a technician is ready to evaluate the engine's condition. Other type of engine diagnosis is abnormal noises diagnosis. Malfunction in the engine will reveal itself first as an unusual noise. This can happen before the problem affects the driveability of the vehicle. Problems such as loose pistons, badly worn rings or ring lands, loose piston pins, worn main bearings and connecting rod bearings, loose vibration damper or flywheel, and worn or loose valve train components all produce telltale sounds. Noise Diagnosis