1 / 8

Engine Diagnostic

Engine Diagnostic. Introduction. 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.

sparksn
Télécharger la présentation

Engine Diagnostic

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Engine Diagnostic Introduction • 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 • several primary test that conducted to determine engine condition: • 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

  2. Engine Diagnostic • related tools that used to diagnose engine faults: • Cylinder compression tester • Cylinder leakage tester • Exhaust gas analyzer • Engine analyzer • Tachometer • Dwellmeter • Service bay diagnostic computer (ECU Scanner) • 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

  3. Engine Diagnostic • Two types of cylinder compression test: • Dry test – normal compression test • 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: • The worn / fault of piston • Piston rings • Cylinder wall

  4. Engine Diagnostic • If reading is same, fault may came from the valve assembly & head gasket: • broken of valve spring – cause valve sticking • incorrect valve adjustment – valve open to short or not seating • sticking valves – not seating • worn or burn of valves and valves seat – valve not seating • worn of camshaft or lifter – incorrect valve operation (open to short) • blown head gasket – pressure goes to the other cylinder or water jackets 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.

  5. Engine Diagnostic

  6. 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

  7. 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.

  8. Engine Diagnostic • Once the compression, cylinder leakage, vacuum, and power balance tests are performed, a technician is ready to evaluate the engine's condition. Noise Diagnosis • 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.

More Related