GENERAL ENGINE DIAGNOSIS n Chapter 4 n Classroom Manual –Page 73 n Lab Manual –Page 77 n Tasks I-A-1 thru I-A-8 CBC AUTOMOTIVE RK

OBJECTIVES n Properly determine the causes for the customer complaints associated with engine operation. n Perform a complete engine evaluation test series, including dry compression test, cylinder leakage, engine vacuum, and power balance testing. CBC AUTOMOTIVE RK

OBJECTIVES n Evaluate the engines condition as indicated by engine test series results and make recommendations for repair. n Determine the causes of common engine problems such as leaks, excessive oil consumption, and loss of power. n Diagnose the cause of all unusual noises. n Determine the causes for engine no-start.

INTRODUCTION n Not all engine problems require rebuilding. n Properly (completely) diagnose. n Repair without loss of time. n Without excessive expense to the customer. CBC AUTOMOTIVE RK

DETERMINING NEEDED REPAIRS n Compression loss - symptoms –Oil consumption –Excessive emission levels –Lack of performance n Compression reading depends on, –Cylinder head sealing –Piston, ring, and cyl wall condition –Valve sealing CBC AUTOMOTIVE RK

LEAK DIAGNOSIS n External or Internal n Oil leaks n Coolant leaks n Vacuum leaks n Compression leaks n Exhaust leaks CBC AUTOMOTIVE RK

LEAKS - CAUSES n Deteriorating seals or gaskets. n Cracked castings. n Broken or stripped bolts. n Defective components. n Abnormal crankcase pressure. CBC AUTOMOTIVE RK

LOCATING LEAKS n Visual inspection. n Possibly clean engine and inspect again. n Chemical dye test. n Low- and high-pressure air testing. –For oil leaks. n Cooling system pressure test. n Hydrocarbon test. CBC AUTOMOTIVE RK

VACUUM LEAKS n Vacuum is required for the air/fuel mixture to be pushed into the cylinder. n A vacuum leak causes the engine to run lean. n Find vacuum leaks with, –Stethoscope –carb cleaner n Causes vacuum hoses, components. CBC AUTOMOTIVE RK

EXHAUST DIAGNOSIS CBC AUTOMOTIVE RK n Exhaust contains carbon monoxide. n The color, smell, and sound of the exhaust can provide clues to internal engine condition.