The document provides information on inspecting and diagnosing engine condition through various tests. It describes how to perform compression tests, cylinder leakage tests, oil pressure tests, and listen for engine noises to determine problems. Visual checks of fluid levels and leaks are also discussed. Causes of common exhaust smoke colors and problems revealed through specific engine noises are explained.

5. Figure 8-1 It is very important to use fender covers to protect the paint of the vehicle from being splashed with brake fluid. Use a binder clip, available at local office supply stores, to clip the fender cover to the lip of the fender, preventing the fender cover from slipping.

7. (Continued) White smoke or steam from the exhaust is normal during cold weather and represents condensed steam. Every engine creates about 1 gallon of water for each gallon of gasoline burned. If the steam from the exhaust is excessive, then water (coolant) is getting into the combustion chamber. Typical causes include a defective cylinder head gasket, a cracked cylinder head, or in severe cases a cracked block. See Figure 8-3. NOTE: White smoke can also be created when automatic transmission fluid (ATF) is burned. A common source of ATF getting into the engine is through a defective vacuum modulator valve on the automatic transmission. White (steam) Black exhaust smoke is due to excessive fuel being burned in the combustion chamber. Typical causes include a defective or misadjusted throttle body, leaking fuel injector, or excessive fuel-pump pressure. Black Blue exhaust indicates that the engine is burning oil. Oil is getting into the combustion chamber either past the piston rings or past the valve stem seals. Blue smoke only after start-up is usually due to defective valve stem seals. See Figure 8-2. Blue Possible Causes Typical Exhaust Smoke Color

8. Figure 8-2 Blowby gases coming out of the crankcase vent hose. Excessive amounts of combustion gases flow past the piston rings and into the crankcase.

9. Figure 8-3 White steam is usually an indication of a blown (defective) cylinder head gasket that allows engine coolant to flow into the combustion chamber where it is turned to steam.

17. Figure 8-4 Typical valve (rocker cover) gasket leak. Always check the highest and most forward parts of the engine that are wet when attempting to find a fluid leak.

18. Figure 8-5 A leaking front crankshaft seal.

23. Figure 8-6 Pushrod worn through a rocker arm.

24. Figure 8-7 Cracked drive (flex) plate. The noise this plate made was similar to a rod-bearing knocking noise.

25. Figure 8-8 An accessory drive belt tensioner. Most tensioners have a mark that indicates normal operating location. If the belt has stretched, this indicator mark will be outside of the normal range. Anything wrong with the belt or the tensioner can cause noise.

26. Figure 8-9 A defective serpentine belt can cause a variety of noises including squealing and knocking, similar to a main-bearing knock.

30. Figure 8-10 To measure engine oil pressure, remove the oil pressure sending (sender) unit usually located near the oil filter. Screw the pressure gauge into the oil pressure sending unit hole.

32. Figure 8-11 The oil pressure switch is connected to the warning lamp indicating to the driver that the oil pressure is low.

33. Figure 8-12 The paper test involves holding a piece of paper near the tailpipe of an idling engine. A good engine should produce even outward puffs of exhaust. If the paper is sucked in toward the tailpipe, a burned valve is a possibility.

42. Figure 8-13 A two-piece compression gauge set. The threaded hose is screwed into the spark plug hole after removing the spark plug. The gauge part is then snapped onto the end of the hose.

44. Figure 8-14 Use a vacuum or fuel line hose over the spark plug to install it without danger of cross-threading the cylinder head.

47. Figure 8-15 A compression test could have detected this badly burned exhaust valve, and a cylinder leakage test (leak-down test) could have been used to determine the exact problem.

59. Figure 8-16 A typical handheld cylinder leakage tester.

61. Cylinder #3 is the weak cylinder. 70 6 75 5 65 4 15 3 70 2 75 1 RPM Drop When Ignition is Shorted Cylinder Number

63. Figure 8-17 Using a vacuum hose and a test light to ground one cylinder at a time on a distributorless ignition system works on all types of ignition systems and provides a method for grounding out one cylinder at a time without fear of damaging any component.

69. Figure 8-18 A typical vacuum gauge showing about 19 in. Hg of vacuum at idle—well within the normal reading of 17 to 21 in. Hg.

70. Figure 8-19 An engine in good mechanical condition should produce 17 to 21 in. Hg of vacuum at idle at sea level.

71. Figure 8-20 A steady but low reading could indicate retarded valve or ignition timing.

72. Figure 8-21 A gauge reading with the needle fluctuating 3 to 9 in. Hg below normal often indicates a vacuum leak in the intake system.

73. Figure 8-22 A leaking head gasket can cause the needle to vibrate as it moves through a range from below to above normal.

74. Figure 8-23 An oscillating needle 1 or 2 in. Hg below normal could indicate an incorrect air-fuel mixture (either too rich or too lean).

75. Figure 8-24 A rapidly vibrating needle at idle that becomes steady as engine speed is increased indicates worn valve guides.

76. Figure 8-25 If the needle drops 1 or 2 in. Hg from the normal reading, an engine valve is burned or not seating properly.

77. Figure 8-26 Weak valve springs will produce a normal reading at idle, but as engine speed increases, the needle will fluctuate rapidly between 12 and 24 in. Hg.

78. Figure 8-27 A steady needle reading that drops 2 or 3 in. Hg when the engine speed is increased slightly above idle indicates that the ignition timing is retarded.

79. Figure 8-28 A steady needle reading that rises 2 or 3 in. Hg when the engine speed is increased slightly above idle indicates that the ignition timing is advanced.

80. Figure 8-29 A needle that drops to near zero when the engine is accelerated rapidly and then rises slightly to a reading below normal indicates an exhaust restriction.

86. Figure 8-30 A back pressure testing tool can be assembled by using an 18-mm air-holding fitting and a 1/4-inch male barb fitting. Most oxygen sensors use an 18-mm thread and the barb fitting can be used to attach a rubber hose leading to a pressure gauge. Both of these low-cost parts are available at most automotive parts stores.