3387002 lubricating oil system troubleshooting

7/28/2019 3387002 Lubricating Oil System Troubleshooting

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FOREWORD

Lubricating oil is obviously one of the most important in-

gredients to be found in any engine. And the way it flows through

the engine, lubricat)ng the moving parts, is just as important

as the oil itself.

This is what we've attempted to teach you in our program.

Keep in mind that it's a very important step in becoming a

competent engine failure troubleshooter. Study it well!



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2. This program is the first of two complete programsdealing with the lubricating oil systems in CumminsDiesel Engines. Its purpose is to completely famil-iarize you with these systems to enable you to solve

most of th.e problems that may arise in Cummins

diesel engines. Then, the

3. second program, which deals with troubleshootingand failure analysis of the lube system, will be easier

to understand.

4. So let's start at the bdginning. What is lubricatingoil? Webster sSlYs it's a substance capable of re-ducing friction, heat, and wear when introduced

between solid surfaces. Sounds logical, doesn't it?But there's more to it than this.



5. The majority of lubricating oils marketed in NorthAmerica, and other places throughout the world, are

designed to meet oil performance specificationswhich have been established by the U. $. Depart-ment of Defense and the Automobile Manufacturers

Association. The

6. American Petroleum Institute (API} lubricating oil

nomenclatures have been introduced, and are ap-

pearing on many current oil labels. Many of these

nomenclatures

7. merely simplify the previous nomenclatures used to

designate present oils.. Others are new -there is noequivalent specification. In

8. Cummins Service Bulletin 3379002-00, we find that



9. the cc classification describes oil that provides

protection against low-temperature sludge and rust.It also provides good high-temperature perform-

ance. Also

10. included in this Service Bulletin are Cummins rec-

ommendations for break-in oil, viscosity, additives,oil analysis, oil filters, and oil change periods. It's

really very interesting. ..browse through it thenext chance you get.

11. OK, let's assume we've got the right kind of oil in

the engine. So just exactly what does oil do in an

engine? Well, you may have heard this a thousandtimes, but here it is one more time. Lube oil performs

12. four functions in an engine. It lubricates, cools,

cleans, and seals.



13. It lubricates all moving parts in an engine by pro-

viding a thin, protective coating between all moving

parts, during engine operation.

14. It cools the parts that it contacts. As the oil flows

through the engine, it absorbs much of the heat

created by friction and combustion. Then, as thisoil passes through the oil cooler, the heat is trans-

ferred to the engine coolant.

15. Lube oil cleans the engine. As it passes through

the drillings and passages, the oil picks up foreignparticles and dirt that can form in an engine. This

foreign material is trapped in the oil filter.

16. Lube oil helps to seal the combustion chamber

from the crankcase by forming a thin film between

the piston rings and the cylinder wall.



17. Most of you are familiar with the parts of the engine

that hold and carry the oil. Let's briefly discusseach one.

18. Naturally, we have a place to hold the oil- the oil

pan. Oil pans come in many different styles and

configurations, depending on front-axle configura-tions, location, oil pan capacity, operation angu-larity, and so forth. Oil pails are made for any

application, mainly

9. automotive,

20. industrial,



21. construction,

22. and marine.

23. Construction applications, especially, require awide variety of different oil pans, becaus'e of the

many different types of vehicles used in construc-

tion work.

24. In the basic engine, the lube pump pulls oil from

the pan through a suction tube and screen assem-bly. The suction tube may be "



25. internal,

26. or external, depending on the kind of engine

27. On in-Iine engines, lube pumps come in several

different styles to fit many different applications.

However, there are only three basic models: the

single-capacity pump; the double capacity, doublepump; and the double-capacity, single pump.

28. The single-capacity pump, such as this one, was

used before 1958. Its only purpose was to pump oilfrom the oil pan to the engine. About this time



29. turbo's were coming on strong. Because of the in-

creased combustion heat caused by turbochargingan engine, pistons, rings and liners were subjectedto severe operating conditions. So we came up with

30. a method of cooling the piston with lube oil, which

allowed extended engine life. ..we just had one

problem -the single-capacity pump couldn't han~

die the necessary, additional oil flow. The

31. double-capacity, double pump took care of the

additional flow volume on automotive applications.One set of gears pumps oil to the engine. The otherset pumps oil to\the piston-cooling nozzles. This

pump is also used on

,32. construction applications. In naturally aspiratedengines, one set of gears pumps oil t.o the engine.The other set.



\ 33. pumps oil from the shallow end of the pan to the

sump, when the engine is being operated in a "tilt"situation. This "scavenging" process ensures that

oil is always available in the sump, ready to be

pumped through the engine.

34. In turbocharged construction engines, the doubl.e-

capacity, double pump must have a third set ofgears: one for the engine, one for scavenging, and

one for piston cooling.

35. The double pump is still used in some automotive

applications today- one section for the engine,one for piston cooling. However, in 1969 we intro-duced anew, high-capacity pump known tech-

nically as the

36. double-capacity, single pump. A single set of longgears easily handles the oil flow to the engine and

the piston-cooling nozzles.



.37. In older lube pumps, a pressure regulator dumpsoil back to the pan whenever the oil pressure ex-

ceeds approximately 70 psi. On

38. FFC (Full-Flow Cooling) engines, this regulator has

been moved to the front cooler support. It contrclsthe pressure of the oil before it passes through the

filter element. In our next program, we'll discussthe complete oil flow through the filter-cooler as-

semblies, along with some troubleshooting pro-cedures. A

39. high-pr,essure by-pass valve is now located in the

lube pump, where the regulator was before. This

valve dumps oil back into the pan when the oil

pressure exceeds 140 psi, which usually occurswhen

40. the operator goes out on a cold, frosty morning and

sticks his foot in the fuel pump. The stiff oil isforced into the engine lube system, where it could

cause a ruptured oil filter element.



41. The full-flow lube oil filter may be mounted on the

lube pump. ..

42. the oil cooler. ..

43. or "remote-mounted" with flexible lines leading to

and from the engine. Each of these filters performs

the same function:

44. As the oil passes through the filter element, most

of the larger foreign particles suspended in the

oil are trapped on the outside of the element.

Eventually,



45. this element will become clogged, and must bechanged. But, let's assume that this maintenance

step is neglected becauSe the owner has a poor

maintenance program. A

46. safety device, called a by-pass valve, is located in

the filter head. When the oil pressure differentialbefore the filter and after the filter reaches approx-

imately 37 psi,

47. this valve opens. At this time; all the oil is by-passing the filter element. It travels on through the

, engine oil passages, lubricating .the engine parts.

But now there's one big difference -

48. dirt, meta1 particles, and other foreign materiaf~:are

being r~-circulated through the engine. Well, dirtYoil is better than no oil -for awhile. ...Most

turbocharged engines have a



.

49. lubricating oil by-pass filter plumbed into the engine.

Its filtering media is much finer, less porous, than

the element in the full-flow filter. For this reason,

50. oil passes through the by-pass filter very slowly. ...

Its purpose is to assist the full-flow filter by trapping

the finer dirt particles that get through the more

porous filter. So much for oil filtering, a very im-

portant part of lubrication. Another important

51. part of lubrication is cooling. Lubricating oil coolers

come in a variety of shapes and sizes,

52. depending on the engine and ttie application. Someare short,

i~.

..."'"



53. some are long. ..

54. and some are the plat~-type design. But they all

perform the same function: (1) they remove excess

engine heat from the oil during high engine loadsand speeds, and (2) they allow the oil to heat up

fast when the engine'is started.

55. In the tube-bundle type ofcooler, the coolant passes

through the tubes, while

56. the lube oil circulates around the outside of these

tubes.



57. On the K engines, the lube oil flows through the

inside of the cooler elements, while the coolantflows around the outside of the elements.

58. A commonly-known fact is that two different tem-

peratures will tend to equalize by heat flowing tocold. With this idea in mind, let's start up a cold

engine.

9. Since the engrne coolant is much thinner than the

oil, and since the coolant contacts most of the areaaround each combustion chamber, it heats up.faster than the lube oil. At this time, then, the

coolant warms the oil, allowing it to flow morefreely. Now the

60. engine is up to normal operating temperature. The

oil is absorbing heat from the engine parts, andcarrying it through the cooler. The thermostat,radiator, and fan are keeping the coorant at about180Q F. The oil may easily reach 250Q F. for short

periods of time.



61. So now what happens? Right. Heat passes to cold.

The coolant helps to maintain a sump oil temper-ature of 180 to .225° F., a temperature range which

assures good lubrication in the engine during

operation.

62. Piston-cooling nozzles make up another important

part of the rube system. As we mentioned earlier,because of the terrific cylinder combustion heat

created by turbocharging an engine, piston-coolingnozzles are used on ~ost turbocharged engines tocool the pistons. Each nozzle

63. directs a continuous oil spray ~p and into the

bottom of the piston. The

64. last part of the lube system we'll discuss is at least

as important as any other part -the oil temper-

ature and oil pressure gauges. The

1~



65. oil temperature gauge on most engines should, read

between 180 and 225° F. in the sump during normal

operating conditions. although 250° F. for shortperiods of time is not uncommon. The most im-

portant information this gauge can indicate is asudden rise in the temperature of the oil. The main

purpose of the

" 66. oil pressure gauge is to indicate any drop in oil

pressure. Normal pressures vary according to the

engine family. However, a good average is 5 to 20psi at low idle, and 40 to 75 psi at high idle, with

the engine at a normal operatiRg temperature.

7. We've covered the lube oil system parts and their

functions in different engines. Now let's study theoil flow in these engines, which is the final step in

our preparation for troubleshooting.

68. We'll use several different basic engines, in an

effort to familiarize'you with the oil flow in almost

any engine you may work on.

04"7



69. In the original NT engine, the lube oil pump drawsthe oil from the pan. At the pump outlet , the oil flow

splits in two directions-one across the gear cover

70. to the piston-cooling rifle on the exhaust manifold

side of the engine,

71. and the other to the accessory drive and air com-

pressor; then on across the front of the block,

72. to the oil cooler. The oil flows around the outside

of the tube bundle,



73. then ~hrough,the front cooler support and oil filter.If the filter is clogged, the by-pass valve opens,

a11owing the dirty oil to continue on through theengine. As oil comes from the filter head, the flow

splits once again, one stream going back acrossthe front of the block,

74. the other going to the turbo. At the

75.. front of the block, oil is routed to number one cam

bushing. Then it trows to the main oil rifle. At this

point, .

76. the oil flows toward the rear of the block, feeding

the main bearings, rod bearings, remaining cam

bushings, cam followers, and rocker levers. Thiscompletes theoir~flow in the NT engine.'



77. In the FFC engine, oil is drawn from the pan,through the suction tube, by .the lupe pump. The

high-pressure by-pass valve dumps oil back to the

pan when the pressure is too high. Oil is forced

across the front of the: block,

,78. to the oil cooler. The pressure regulator in the

cooler d!Jmps oil back to the pan when the pres-

sure exceeds the maximum limit. From the cooler,

the oil

.

79. flows downward, through the oil filter. If

80. the filter is clogged, the by-pass valve opens and

allows the dirty oil to continue on through the

engine. After



81. leaving the filter, oil flow is divided near the front of

the engine. One passage feeds the piston-cooling

nozzles. Another

82. passage route$ oil to the turbo. A

83. third passage routes oil across the front of the

block to No.1 cam bushing. The

84. fourth passage carries the oil, through a tube in the

gear cover, to the accessory drive and the air com-pressor. In the

.



85. main oil rifle, the oil flows to the remaining cambushings, all of the mains, rods, cam followers, androcker levers. This completes the oil flow in the

FFC engine.

86. In the KT -1150 engine, oil is drawn from the pan,through the suction tube, into the lube pump. At this

point, the pressure regulator will route oil from thedischarge side of the pump back to the inlet side, ifoil pressure exceeds the specified maximum. From

the lube pump,

87. oil passes through 1he oil cooler elements an-d the

oil transfer tube. This Clil transfer tube design pro-vides the necessary openings when the oil filters

must be mounted on this side of the engine.Through a drilling between cylinders five and six,

the oil

88. passes .to the oil filters. A single by-pass valve inthe filter head allows constant engine lubrication if

the filter elements become clogged. When it leavesthe filter head, the oil flow splits.



89. One passage leads to the piston-cooling rifle

where a pressure-relief valve limits oil flow to th

piston-cooling nozzles when the pressure is below20 psi. The other passage routes oil through themain oil rifle. This oil travels toward the front of th

engine, and toward the rear of the engine,

90. feeding the cam bushings, cam followers, rocker

levers;

bearings, rod bearings, piston-pin1. the main

bushings;

92. then, through passages in the gear housing, to thecamshaft gear, barring mechanism gear,. idler

gears, water pump drive gear, power-steering gearand the accessory drive gear. The fan has roller

element bearings which are lubricated by oil splash.From another drilling in the



93. ge8rhousing, oil flows to the turbo,

94. then drains back to the crankcase. This completes

the oil flow in the KT-1150 engine.

95. In the VT -1710 engine, oil is drawn from the oil pan

by the internally-mounted lube pump. The pressureregulator dumps oil back into the pan when the oilpressure reaches a pre-determined psi. From the

pump, oil

96. flows through tubes and drillings to the oil cooler,

where it passes around the outsides of the tubes,



97. on its way to the oil filters. Three by-pass valvesin the filter head -one for each element- allow

oil to flow to the engine if any of the elements

become clogged. The oil passes from the oil filters

98. to ihe main oil galley in the center of the cylinder

block. At this point, oil flows to the remaining

parts of the engine:

99. the cam bushings, tappets, and rocker levers;

100. the turbochargers, and



101. the piston-cooling nozzles. A check valve at the

front of the block, in the mairl oil galley, restrictsoil flow to the piston-cooling nozzles when the

engine is idling. This valve helps to ensure properoil pressure to the engine at any rpm. The oil flows

from the main oil galley to ~)I o.f the

102. main bearings, rod bearings, and piston-pin bush-ings. This concludes the oil flow in the VT;.1710

engine.

103. In the VT -903 engine, oil is drawn from the pan bythe internally-mounted lube oil pump, and forced

into a drilling in the cylinder block. The pressureregulator dumps oil back to the pan when the oilpressure reaches a pre-determined maximum

limit. Oil then

104. enters the oil filter. The by-pass valve in the filterhead allows oil to by'-pass the element when it

becomes clogged. The oil then continues onthrough the oil cooler. From the front of the cooler,



105. oil is routed to the front center of the block, whereit splits into two flows, one going to No.1 main

bearing and the related rods, the other to No.1cam bushing. From this cam bushing, oil flowsintermittently to the left-bank rocker levers. Mean-

while, the oil is flowing to the right-bank oil riflewhere it feeds the right-bank tappets. At the same

time, it flows

106. along the left-bank oil rifle, feeding the left-bank

tappets, and the remaining main bearings, rods,and cam bushings. From the

107. gear housing, oil is routed to the turbo and the air

compressor. Oil is

108. fed intermittently from No.5 camshaft bushing to

the right-bank rocker levers. This completes the

oil flow in the VT -903 engine.



109. In the V555 engine, oil is drav\'n from the oil pan,

throufJh the internally-mounted lube oil pump, andforced through a cylinder block c'.rilling. Travelingthrough a passage in the filter-cooler support, theoil passes to

110. the oil cooler, around the tubes, then back to the

oil filter through a special passage near the lowerside 6f the oil cooler housing. When it ieaves thefilter, \

111. the oil enters another cylinder block passage,

where it intersects with several branches. At thfspoint, oil is routed to the air compressor, and to avertical drilling between No.5 main bearing andthe related rods, and No.5 cam bushing. Oil is fed

intermittently from No.5 cam bushing to the right-bank rocker levers. At the same time,

112. oil flows along the right-bank oil rifle, lubricating

the i~jector tappets; No's. 2, 3 and 4 main bear-

ings, and related rods; and No's. 2, 3 and 4 cambushings. At the



113. front of the engine, the oil flows to No.1 main

bearing and related rods, and No.1 cam bushing.From the cam bushing, oil flows intermittently tothe left-bank levers. It continues over to the lefside of the engine,

114. to the left-bank oil rifle, where .it feeds the left-bank injector tappets. This completes the oil flowin the V-555 engine. We've discussed many

115. basic phases of the lube system, including lubeoil itself,

116. most of the related parts and their functions,



117. and oil flows in six 'of our stand3rd engines. If youknow and understand the facts .hat we've talked

about, then you're sure to have

118. very little trouble understanding Program II ofCummins lube oil systems. Whenever you trouble-shoot an engine failure. always keep in mind that

"Effective, successful troubleshooting requires a

thorough knowledge of the engine systems, parts,

and functions."

119. A Profit from Knowledge presentation

3387002 lubricating oil system troubleshooting

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