DOOSAN Generator diesel engine DE12T, P126TI, P126TI-1, P126TI-II, PU126TI. Operation and Maintenance Manual

Valve spring

● Visual check

Visually check the exterior of the

valve springs for damage, and

replace if necessary.

● Valve spring free length

Use a vernier caliper to measure

the valve spring free length.

If the measured value is less than

the specified limit, the valve spring

must be replaced.

(mm)

Spring free Length

Standard

Intake valve

75.5

EJM2049I

Exhaust

Inner

valve

Outer

75.5

● Valve spring inclination

Use a surface plate and a square to

Inclination

measure the valve spring inclination.

If the measured value exceeds the

specified limit, the valve spring must

be replaced.

(mm)

Standard

Limit

Square

Valve spring

EJM2050I

1.0

2.0

Inclination

● Valve spring tension

Use a spring tester to measure the

valve spring tension if the measured

value is less than the specified limit,

the valve spring must be replaced.

Spring

Set Length

Limit

Spring tester

force

Valve Spring

Intake

Tension at 37

61.8 ~

EA0M4056

61.8 kg

valve

mm Set

68.3 kg

Length

Exhaus

36.1 ~

Inner

34 mm

36.1 kg

t valve

39.9 kg

Disassembly and Reassembly of Major Components

77 -

9.2.4. Rocker arm shaft assembly

Rocker arm shaft

● Rocker arm shaft run-out

Place the rocker arm shaft on two V

blocks and inspect the shaft for

bend using a dial gauge.

If the amount of this run-out is

small, press the shaft with a bench

press to correct the run-out Replace

the shaft if the measured value

exceeds the limit.

(mm)

EDM2037I

Limit

0.2

● Rocker arm shaft diameter

With an outside micrometer, measure

the rocker arm shaft diameter at the

point where the rocker arms have

been installed.

Replace the rocker arm if the amount

of wear is beyond the specified limit.

(mm)

Standard

Limit

Ø23.978 ~ Ø23.959

Ø23.75

EA8M3002

Rocker arm

● Visual check

Visually check the face of the rocker

arm in contact with the valve stem end

for scores and step wear. If the wear is

small, correct it with an oil stone or

grinding paper of fine grain size.

Rocker arm with a considerable amount

of step wear should be replaced.

● Diameter of the rocker arm bushing

Measure the inside diameter of the

rocker arm bushing with an inside

micrometer or vernier calipers, and

compare the measured values with

the rocker arm shaft diameter.

If the clearance exceeds the limit,

replace either bushing or shaft,

whichever worn more.

EA0M4059

78 -

isassembly and Reassembly of Major Components

(mm)

Standard

Limit

0.020 ~ 0.093

0.2

Tappet & push rod

● Clearance

Measure the clearance of the tappet

and tappet holes of the cylinder

block. If the value is beyond the

specified limit, replace tappets.

(mm)

Standard

Limit

0.035 ~ 0.077

0.15

● Visual check of tappet

Visually check the face of the tap-

pets in contact with the cam for pit-

ting, scores or cracks, and replace if

(1) Unevenness

(2) Crank

(3) Normal

severely damaged. If the amount of

cracks or pitting is small, correct

with an oil stone or grinding paper.

Abnormal

EA0M4070

Disassembly and Reassembly of Major Components

79 -

● Outside diameter

With an outside micrometer, mea-

sure the tappet outside diameter If

the measured value is beyond the

limit, replace tappets.

(mm)

Tappet Dia

Ø19.944 ~ Ø19.965

(mm)

Standard

Limit

EDM2061I

Tappet

0.035 ~

0.15

Clearance

0.077

● Push rod run-out

(mm)

Limit

0.3 or less

Use a feeler gauge to measure the

push rod run-out.

Roll the push rod along a smooth

flat surface as shown in the figure.

Feeler gauge

EA0M4073

9.2.5. Cam shaft

1) Cam

● Cam lobe height

(mm)

Standard

Limit

Cam journal

Ø59.86 ~

Ø59.52

diameter(A,B)

Ø59.88

Use a micrometer to measure the

I II

cam journal diameter.

If the measured number is less than

EA0M4062

the specified limit, the camshaft

must replaced.

● Cam surface

Use a micrometer to measure the

cam journal diameter.

If the measured number is less than

the specified limit, the camshaft

must replaced.

80 -

isassembly and Reassembly of Major Components

Cam shaft

● Clearance between camshaft journal

& camshaft bush

- With an outside micrometer, mea-

sure the camshaft journal diameter.

- Measure the inside diameter of the

camshaft bushing on the cylinder

Camshaft bearing

block using a cylinder bore indicator,

and compare the measured value

with the camshaft outside diameter to

determine the clearance.

(mm)

EA0M4063

Standard

Limit

0.050 ~ 0.128

0.2

Replace the bushing if the measured

value is beyond the specified limit.

● Run-out

Support the camshaft on two V

blocks and check for run-out using

a dial indicator. Correct or replace

the cam shaft if the amount of run-

out is beyond the value indicating

need for servicing.

(mm)

Standard

Limit

EA0M4066

0.05

0.2

Cam shaft & play

● Push the thrust plate toward the

cam gear.

● With a feeler gauge, measure the

clearance between the thrust plate

and camshaft journal.

● If the end play is excessive, replace

the thrust plate.

(mm)

Standard

Limit

0.13 ~ 0.27

0.3

EA0M4067

Disassembly and Reassembly of Major Components

81 -

9.2.6. Crank shaft

Defect check

● Visually check the crankshaft journal

and crank pins for scores or cracks.

● Using a magnetic particle test and

color check, inspect the crankshaft

for cracks, and replace the crank-

shaft which has cracks.

Wear

● With an outside micrometer mea-

sure the diameter of the crankshaft

journals and pins in the directions

as shown, and compare the mea-

sured values to determine the

amount of wear.

● If the amount of wear is beyond the

limit, have the crankshaft ground

and install undersize bearings. How-

EAMD057I

ever, if the amount of wear is within

the limit, you can correct the wear

using an oil stone or oiled grinding

paper of fine grain size. (Be sure to

use grinding paper which has been

immersed in oil.)

(mm)

Standard

Limit

Ø95.966 ~

Journal diameter

Ø94.966

Ø95.988

Ø82.966 ~

Pin diameter

Ø81.966

Ø82.988

EFM2047I

* Undersize bearings available

◆ Standard

◆ 0.25 (Inside diameter is 0.25 mm lesser than the standard size.)

◆ 0.50 (Inside diameter is 0.50 mm lesser than the standard size.)

◆ 0.75 (Inside diameter is 0.75 mm lesser than the standard size.)

◆ 1.00 (Inside diameter is 1.00 mm lesser than the standard size.)

Undersize bearings are available in 4 different sizes as indicated above, and the crankshaft

can be reground to the above sizes.

82 -

isassembly and Reassembly of Major Components

NOTE :

When regrinding the crankshaft as

" R "

described below, the fillet section

ëRí should be finished correctly.

" R "

Avoid sharp corners or insufficient

fillet.

" R "

* Standard values of "R”

Normal

Poor

① Crankshaft Pin "R" : 4.5

-0.2

EFM2048I

② Crankshaft journal "R" : 4

-0.2

3) Crankshaft run-out

● Support the crankshaft on V blocks.

● Turn the crankshaft with a dial indi-

cator placed on the surface plate

and take the amount of crankshaft

run-out.

(mm)

Standard

Limit

0.05

0.1

Disassembly and Reassembly of Major Components

83 -

9.2.7. Crank shaft bearing & connection rod bearing

Visual check

Visually check the crankshaft bearing

and connecting rod bearing for scores,

uneven wear or damage.

Oil clearance between crankshaft & bearing

● Main bearing clearance (Method 1)

Install the main bearing in the cylinder

block, tighten the bearing cap to

specified torque, then measure the

inside diameter.

Torque

30 kgm

(mm)

Standard Dia.

Ø96.06 ~ Ø96.108

Compare the two values obtained

through measurement of main bearing

inside diameter with the outside diame-

ters of crankshaft journals to determine

the oil clearance.

(mm)

Standard

Limit

0.072 ~ 0.142

0.25

● Connecting rod bearing clearance

Install the connecting rod bearing in

the connecting rod bearing cap,

tighten the connecting rod cap bolts

to the specified torque, then mea-

sure the inside diameter.

Torque

28 kgm

(mm)

Standard Dia.

Ø83.02 ~ Ø83.092

84 -

isassembly and Reassembly of Major Components

Compare the two values obtained

through measurement of connecting

rod bearing inside diameter with the

outside diameters of crankshaft pins

to determine the oil clearance.

(mm)

Standard

Limit

0.049 ~ 0.119

0.20

EAMD060I

● If the clearance deviates from the specified range, have the crankshaft journals and pins

ground and install undersize bearings.

● Connecting rod bearing clearance (Method 2 : with plastic gauge)

Assemble the crankshaft on the cylinder block and put the plastic gauge on journal and pin

of crankshaft and then after assembling bearing cap, tighten the bolts at the specific torque.

Again after disassembling the bearing cap by removing the bolts, take out the flatted plastic

gauge and measure the width of plastic gauge by means of plastic gauge measuring scale.

This is the oil clearance.

Bearing spread and crush

● Inspection

Check to see that the bearing

requires a considerable amount of

finger pressure at reassembly opera-

tion.

O A

O B

Spread = O A - O B

EDM2047I

Disassembly and Reassembly of Major Components

85 -

● Crankshaft bearing crush

Install the bearing and cap in the

cylinder block, retighten the bolts to

specified torque, unscrew out one

bolt completely, then measure the

clearance between the bearing cap

and cylinder block using a feeler

gauge.

(mm)

EA6M063I

Standard Dia.

0.15 ~ 0.25

● Connecting rod bearing crush

Install the bearing and cap in the

connecting rod big end, retighten

the bolts to specified torque,

unscrew out one bolt completely,

then

measure the

clearance

between the bearing cap and con-

necting rod big end using a feeler

gauge.

EA6M064I

(mm)

Standard

0.086 ~ 0.116

crank shaft end play

● Assemble the crankshaft to the cyl-

inder block.

● With a dial gauge, measure crank-

shaft end play.

(mm)

Standard

Limit

0.15 ~ 0.325

0.5

86 -

isassembly and Reassembly of Major Components

9.2.8. Piston

1) Visual check

Visually check the pistons for cracks,

scuff or wear, paying particular atten-

tion to the ring groove.

2) Clearance between the piston &

cylinder liner

● With an outside micrometer, measure

Position of measuring

the piston outside diameter at the

outside diameter

points

D1(18mm),

D2(88mm),

D3(124mm)

D3(124mm) away from the lower end

of piston skirt in a direction at a right

D2(88mm)

angle to the piston pin hole.

(mm)

D1(18mm)

Point

Standard Dia.

D1(18mm)

Ø122.870 ± 0.007

EI6OM017

D2(88mm)

Ø122.750 ± 0.009

D3(124mm)

Ø122.450 ± 0.010

● Using a cylinder bore gauge, measure

cylinder liner inside diameter at

points (cylinder top ring contacting face,

middle, and oil ring contacting face on

BDC) in a direction at an angle of 45.

Take the mean value with the largest

and smallest values excepted.

(mm)

Standard

Limit

Ø123 ~ Ø123.023

Ø123.223

● The clearance is computed by subtract-

ing the piston outside diameter from

the cylinder liner inside diameter.

Replace either piston or cylinder liner,

whichever damaged more, if the clear-

ance is beyond the specified limit.

<Clearance between piston and

liner>

(mm)

Standard

0.114 ~ 0.169

Disassembly and Reassembly of Major Components

87 -

9.2.9. Piston rings

Visual check

Replace the piston rings with new ones

if detected worn or broken when the

engine is overhauled.

Piston ring gap

● Insert the piston ring into the upper

portion of the cylinder liner bore so

that it is held at a right angle to the

cylinder liner wall.

● Measure the piston ring gap with a

feeler gauge.

(mm)

Standard

Limit

Top ring

0.30 ~ 0.45

1.5

Feeler gauge

2nd ring

1.0 ~ 1.2

2.0

Oil ring

0.30 ~ 0.50

1.5

Replace piston rings with new ones if

the gap is beyond the limit

EA0M4033

Piston ring side clearance

● Fit the compression ring and oil ring

in the piston ring groove.

Feeler gauge

● With a feeler gauge, measure side

clearance of each ring, and replace

either the ring or piston if the mea-

sured value is beyond the specified

limit.

(mm)

Standard

Limit

EA4M2007

Top ring

0.105 ~ 0.155

2nd ring

0.07 ~ 0.102

0.15

Oil ring

0.05 ~ 0.085

0.15

Piston ring tension

With a tension tester, measure piston

ring tension. Replace the piston ring if

the measured value is beyond the limit.

Standard

Top ring

2.27 ~ 3.41 kg

2nd ring

2.0 ~ 3.0 kg

Oil ring

4.03 ~ 5.57 kg

88 -

isassembly and Reassembly of Major Components

9.2.10. Piston pin

Wear

Measure the amount of wear on the

piston pin at the points as shown.

The measured values are beyond the

limit

(0.005 mm or greater), replace

the pin

(mm)

Standard

Limit

Ø44.995 ~ Ø45

Ø44.990 or less

EA0M4031

Clearance

Measure the clearance between the

piston pin and connecting rod bush-

ing, and replace either of them,

whichever damaged more, if the mea-

sured value is beyond the limit.

(mm)

Standard

Limit

0.003 ~ 0.009

0.011

EA3M2047

Condition check

Check the engaged condition of the

piston and piston pin. If it is possible

to force the pin into the piston heated

with piston heater, the piston is nor-

mal.

When replacing the piston, be sure to

replace the piston pin together.

Disassembly and Reassembly of Major Components

89 -

9.2.11. Connecting rod

Distorsion

Check the connecting rod for distor-

tion. As shown in the figure below,

install the connecting rod to the con-

necting rod tester, and check for dis-

tortion using a feeler gauge. If the

connecting rod is found distorted,

never re-use it but replace with a new

one.

Holes alignment (parallelism)

Measure the alignment of the con-

necting rod piston pin bushing holes

with connecting rod big end holes. At

this time also, use both connecting

rod tester and feeler gauge.

(mm)

Standard

Limit

0.05

0.1 or less

EA0M4034

Wear

● Assemble the connecting rod to the

crankshaft and measure connecting

rod big end side clearance using a

feeler gauge.

● Assemble the connecting rod to the

piston and measure connecting rod

small end side clearance.

● If the measured values are beyond

the limit, replace the connecting rod.

(mm)

Limit

0.5

90 -

isassembly and Reassembly of Major Components

9.3. Reassembly

9.3.1. General precautions

● Wash clean all the disassembled parts, particularly oil and water ports, using compressed air,

then check that they are free from restrictions.

● Arrange the general and special tools in order for engine assembly operation.

● To wet each sliding part, prepare the clean engine oil.

● Prepare service materials such as sealant, gaskets, etc.

● Discard used gaskets, seal rings, and consumable parts, and replace with new ones.

● Apply only the specified torque for bolts in the specified tightening order and avoid over-tight-

ening.

● Be sure to check that all the engine parts operate smoothly after being reassembled.

● Check the bolts for looseness after preliminary reassembly.

● After completing the engine reassembly operation, check if there is missing parts or shortage

of parts.

● Keep your hands clean during the working.

9.3.2. Cylinder block

Cover the floor of the workshop with wood plate or thick paper to prevent damage to the cylin-

der head and place the cylinder block with the head fitting surface facing downward.

9.3.3. Oil spray nozzle

● Tighten and assemble the oil spray

nozzle flange with fixing bolts using

the spray

nozzle jig.

EDM3053I

9.3.4. Tappet and cam shaft

● Undercool a new bush with dry ice

for about

2 hours and press it into

position in the cylinder block using a

bench press. After the pressing oper-

ation, measure the inside diameter of

the cam bush to check if it is not

deformed.

Disassembly and Reassembly of Major Components

91 -

● Apply engine oil to the entire face of

the tappets and slide them into the

tappet holes on the cylinder block.

● Wet the cam bush inside diameter

and camshaft with oil, and carefully

assemble them while turning the cam-

shaft.

● Check to see that the camshaft

rotates smoothly.

EDM2060I

9.3.5. Crankshaft

● Install the main bearing machined

Key groove

with two holes in the cylinder block

Oil port and passage

so that the key is aligned with the

key groove, then apply oil to the

bearing surface.

EA0M4083

● Heat the crankshaft gear for at least

minutes to 120C, then apply

sealant

(Loctite

# 641) to the inside

wall of the heated crankshaft gear

evenly before inserting it to the end

of crankshaft.

EA8M3014

92 -

isassembly and Reassembly of Major Components

● Semi-tighten a bolt at both sides of

the crankshaft, apply engine oil to

journals and pins, then assemble the

crankshaft with the cylinder block by

tightening the fixing bolts.

EAMD075S

● Install the oiled thrust washers with

the oil groove facing outward.

● Install the bearing and thrust washers

to the bearing cap and apply oil to

the bearing and thrust washers.

EAMD077I

● Install the bearing cap by matching

the cylinder block No. with the bear-

ing cap No.

EQM3058I

Disassembly and Reassembly of Major Components

93 -

● Apply oil to the entire part of the bear-

ing cap bolts, then tighten in tightening

sequence to specified torque.

Torque

30 kgm

● After semi-tightening both bolts

evenly, tighten them diagonally speci-

fied torque using a torque wrench as

EQM3059I

follows.

(1) First stage : Coat engine oil over the bolts.

(2) Second stage : Temporary assemble the bolts about 1 ~ 2 threads

(3) Third stage : With impact wrench, tighten up to about 15 kg.m

(4) Fourth stage : With torque wrench, tighten up to about 25 kg.m

(5) Fifth stage : By means of torque wrench, tighten finally in the specified torque. (30 kgm).

● Tighten the bearing cap in the sequence of

4-3-5-2-6-1-7.

● Check to see that the assembled crankshaft turns smoothly.

9.3.6. Flywheel housing

● Temporarily install the guide bar on

the cylinder block.

● Apply gasket to the cylinder block.

● Using the dowel pin and guide bar,

install

the flywheel housing and

tighten the fixing bolts in a diagonal

sequence to specified torque.

Torque

12 kgm

EQM3060I

9.3.7. Rear oil seal

● Apply lubricating oil to the outside of

theoil seal and flywheel housing

inside diameter and fit them over the

crank shaft, then assemble the oil

seal using an oil seal fitting jig.

Oil seal fitting jig

EA8M3003

94 -

isassembly and Reassembly of Major Components

9.3.8. Flywheel

● Install a guide bar into a bolt hole on

the crank shaft, and lift the flywheel to

align the dowel pin with the pin hole

on the flywheel for temporary assem-

bly operation.

● Install bolts in the remaining holes,

take out the guide bar, then install a

bolt in the hole where the guide bar

had been inserted.

EAMD081I

● Tighten the fixing bolts using a torque

wrench in a diagonal sequence to

specified torque.

Torque

18 kgm

EAMD097I

9.3.9. Timing gear case

● Mount gasket using dowel pin on the

cylinder block.

● Install the timing gear case by align-

ing the dowel pin with the dowel pin

hole on the timing gear case.

EAMD082I

9.3.10. Fuel injection pump drive gear assembly

● Mount gasket by aligning the bolt

holes with the pin holes on the

bearing housing.

● Tighten up the fixing bolts in the

direction of fuel injection pump.

EAMD027I

Disassembly and Reassembly of Major Components

95 -

9.3.11. Timing gear

● Install the oil pump idle gear onto the

No.7 bearing cap.

● Install a thrust washer over the cam-

Idle gear pin

shaft and assemble the cam gear by

aligning it with camshaft key groove.

Torque

3.1 kgm

EAMD083I

● With the oil port on the idle gear pin

facing the cylinder block, install the

Idle gear pin

idle gear pin.

EA8M3004

● Install the idle gear by coinciding the

marks impressed on the crank gear,

Mark "2"

cam gear, fuel injection pump drive

Fuel injection

Cam gear

gear, and idle gear.

pump drive gear

1 1

● Install a thrust washer on the idle

Idle gear

gear and tighten to specified torque.

Mark "1"

Torque

7.4 kgm

Crank

Mark "0"

gear

EA8M3005

● Check and adjust the amount of

backlash between gears using a

feeler gauge.

(mm)

Measuring

position

Backlash

Limit

(between)

Cam gear &

0.16 ~ 0.28

0.35

idle gear

Crank gear &

0.16 ~ 0.28

0.35

idle gear

Injection pump &

0.16 ~ 0.28

0.35

idle gear

96 -

Disassembly and Reassembly of Major Components

9.3.12. Timing gear case cover

● Install dowel pin on the timing gear

case.

● Mount a gasket by aligning the fixing

bolt holes with those on the gasket.

● Align the dowel pin with the cover pin

hole, then install the cover with light

tap.

● Tighten the fixing bolts beginning with

the oil pan fitting face.

9.3.13. Front oil seal

● Apply lubricating oil to the outside of

the oil seal and timing gear case

inside diameter and fit them over the

crankshaft, then assemble the oil seal

using an oil seal fitting jig.

Oil seal fitting jig

EAMD086I

9.3.14. Cylinder liner

● Stand the cylinder block so that the

flywheel faces downward.

● Thoroughly clean the liner flange fit-

ting surface and bore inside with

compressed air to prevent the entry

of foreign substances.

● After the cleaning operation, make

the cylinder liner dried up and push it

into the cylinder block by hand.

EAMD087I

● Wet the liner inside diameter with

engine oil.

Disassembly and Reassembly of Major Components

97 -

9.3.15. Piston & connecting rod

● Align the piston pin hole with the

oiled connecting rod small end and

press the piston pin

(by lightly tap-

ping with a rubber hammer) to

assemble the connecting rod with the

piston.

EAMD088I

● Noting the direction of the piston,

make the longer side (machined with

key groove on the bearing) of the

connecting rod big end and the mark

of “DI” impressed on the inside of the

piston face each other in opposite

directions. On the piston head sur-

face, the longer side of connecting

rod big end is in opposite direction

EAMD089I

from the valve seating surface as well

as in the same direction with the nar-

row margin of combustion chamber.

● Install the snap rings and check to

see that it is securely assembled.

● Install the piston ring in the piston

using piston ring pliers.

● Identify the mark "Y" or "TOP" on the

ring end to prevent the top and bot-

tom of the piston ring is interchanged

each other and make the marked top

face upward.

NOTE :

Be sure to make the piston ring end

Marked with the name of piston ring

manulacturing company

marked face("Y" or "TOP") upward.

EAMD090I

98 -

Disassembly and Reassembly of Major Components

● Adjust the angle among individual pis-

45^O

ton ring gaps to

90° and fit a piston

2nd ring gap

Top ring gap

assembling jig onto the piston, Use

care not to match the ring gaps with

the pin direction.

90^O

● Install the bearing by aligning it with

the connecting rod key groove and

Piston pin

apply oil to the bearing and piston.

Oil ring gap

Piston

EA8M3006

● Position the valve seating surface

toward the tappet hole and insert the

piston with hand.

Tappet hole

Use care not to damage the cylinder

liner and piston, and slightly lift and

Valve seating

insert the piston into the cylinder so

that the ring may not be damaged by

the fillet of the liner.

● Install the bearing in the connecting

EAMD092I

rod cap and apply oil.

● Make sure that the manufacture serial

numbers impressed on the connecting

rod cap and connecting rod big end

are identical, and install the connect-

ing rod cap by aligning it with dowel

Serial No.

pin.

EA0M4092

● Wet the fixing bolts with oil, semi-tighten them with hand, tighten them to specified torque

using a torque wrench as follows.

(1) First stage : Coat engine oil over bolts

(2) Second stage : Temporary screw the bolt about 1 ~ 2 threads

(3) Third stage : With torque wrench, tighten at about 15 kgm

(4) Fourth stage : With torque wrench, tighten up to about 22 kgm

(5) Fifth stage : Finally, tighten in the specified torque 28kg.m with torque wrench.

Torque

28 kgm

Disassembly and Reassembly of Major Components

99 -

● Move the bearing cap with hand, and

release and reassemble it if no move-

ment is detected.

EAMD094I

9.3.16. Relief valve

● Assemble the relief valve.

EAMD036I

9.3.17. Oil pump and oil pipe

● Install a dowel pin in the No.7 bear-

ing cap, then assemble the oil pump

with specified torque.

Torque

4.4 kgm

● Assemble the oil suction pipe with the

delivery pipe, then install the bracket

on the bearing cap.

EAMD095I

9.3.18. Oil pan

● Mount gasket and put the oil pan

thereon.

● Place stiffeners and tighten bolts.

● Align the bolt holes with gasket holes

to prevent damage to the gasket and

tighten to specified torque.

Torque

2.2 kgm

EAMD034I

100 -

isassembly and Reassembly of Major Components

9.3.19. Intake & exhaust valves

● Identify the marks of

“IN” and

“EX”

impressed on the valve head before

assembling the valve with the valve

head.

● With a valve stem seal fitting jig,

assemble the valve stem seal with

the valve guide.

● After installing valve springs and

spring retainer, press the retainer with

a jig, then install cotter pin.

● Tap the valve stem lightly with a rub-

ber hammer to check that the valve

is assembled correctly.

Valve spring

compressor

EA0M4007

9.3.20. Nozzle tube

● Apply sealant

(LOCTITE

620) to

the nozzle tube and place the O-ring

over the cylinder head fitting face on

the nozzle tube, then install the noz-

zle tube in the cylinder head.

● Install a guider of the nozzle tube

insert assíy

(Guider

+ Expander) the

Guider

cylinder head, then tighten the nozzle

fixing nuts.

EAMD098I

Disassembly and Reassembly of Major Components - 101 -

9.3.21. Cylinder head

● Install the injection nozzle fixing stud

bolts and water pipe fixing stud bolts.

● Clean the head bolt holes on the cyl-

inder block with compressed air to

remove foreign substances and thor-

oughly clean the gasket fitting face of

the cylinder block.

TOP

● Install head gasket, with 'TOP' mark

facing upward, on the cylinder block

EAMD101I

by aligning the holes with dowels.

Cylinder Head

Asbestos core type

Semi steel type

gasket

Rubber color : Black

Rubber color : Red

Use bolt

12.9T

10.9T

● Check the inside of combustion chamber for foreign substances, and carefully mount the cyl-

inder head assembly in the block by aligning the dowel pin with the dowel pin hole. Be care-

ful not to

damage the head gasket. If the dowel pin is not in alignment, lift the cylinder

head again and then remount it.

● Coat the head bolts with engine oil, then tighten them in proper sequence to the specified

torque.

Type1

Type2

Type3 (12.9T)

Type4 (12.9T)

Type5 (10.9T)

DL08

Type

12.9T

10.9T

M14 x 1.5 x 153

M14 x 1.5 x 150

M14 x 1.5 x 153

M14 x 1.5 x 150

1st : 6 kgm

1st :

6 kgm

1st :

7kgm

1st :

6 kgm

Tighten

24.5 kg.m

2nd : 180°

2nd : 90°+ 90°

torque

Finished : 150°

Finished : 30°

Finished : 90°

However, before tightening bolts, align the side face of 2 cylinder heads with parallel. They

should be adjusted in a straight line exactly.

Disassembly and Reassembly of Major Components - 103 -

(1) First stage

: Coat the bolts with

engine oil.

(2) Second stage

: Tighten

threads with hands.

(3) Third stage

: Tighten at about

kgm with a wrench.

(4) Fourth stage

: Tighten at rotating

angle method 90° with a wrench.

EAMD102I

(5) Fifth stage

: Tighten at rotating

angle method 90° with a wrench.

(6) Sixth stage

: Finally, tighten at

rotating angle method

90° with a

torque wrench .

Especially, all bolts are tightened

simultaneously in each step according

to above process as possible.

EAMD103I

NOTE :

Cylinder head bolts should be

replaced by new one after using two

or three times because of being

loosed as a result of its length too

extended. (Limit length 150mm)

● Coat the push rod with engine oil and

insert it into the push rod hole.

● Adjust the valve clearance as follow-

ing guide.

104 -

isassembly and Reassembly of Major Components

● After letting the #1 cylinder’s piston come at the compression top dead center by turning the

crankshaft, adjust the valve clearances.

● Loosen the lock nuts of rocker arm adjusting screws and push the feeler gauge of specified

value between a rocker arm and a valve stem and adjust the clearance with adjusting screw

respectively and then tighten with the lock nut.

● As for the valve clearance, adjust it when in cold, as follow.

(mm)

Model

Intake valve

Exhaust valve

DE12T

0.3

P126TI series / PU126TI

- By cranking the engine, let #6 cylinder’s valves overlap.

- In time, adjust the valve clearance corresponding to “

” of lower lists.

- Adjust the valve clearance corresponding to “

” of lower lists.

- After reinsuring the valve clearances, retighten if necessary.

● No. 1 Cylinder is located at the side where flywheel was installed.

Flywheel

Intake Valve

Exhaust Valve

Cylinder No.

Crank pulley

ED5OM005

Disassembly and Reassembly of Major Components - 105 -

● Adjust valve clearance with a feeler

gauge and tighten the fixing nuts to

Valve clearance adjust

specified torque.

Torque

4.4 kgm

EA8M3007

9.3.22. Rocker arm assembly

● Apply lubricating oil to the rocker arm

bush and shaft, and assemble the

intermediate bracket with the rocker

arm using fixing bolts.

M10(x2) : 4.4 kgm

Torque

M8 : 2.2 kgm

● Semi-install valve clearance adjusting

bolts onto the rocker arm.

EAMD100I

● Install the spring, rocker arm, bracket,

rocker arm, spring, washer, and snap

ring in the described sequence.

● Install the rocker arm and bracket in

the same direction.

EA8M3008

9.3.23. Injection nozzle

● Install the dust seal with its round

portion facing downward.

● Mount a seal ring

(0.5 mm) on the

seal ring seating surface of the noz-

zle tube and assemble nozzle holder

assembly with the stud bolt with the

nozzle pipe installing

direction fac-

ing outward.

● Be sure to follow the specified torque.

EAMD105I

Torque

1.0 kgm

106 -

isassembly and Reassembly of Major Components

9.3.24. Oil cooler

● Install the oil cooler onto the oil

cooler cover.

● Carefully apply the gasket to prevent

oil leakage.

● Do not damage the gasket and install

the cover onto the cylinder block.

● Connect a connection pipe between

the water pump and oil cooler.

EAMD106I

9.3.25. Oil filter

● Install the oil filter onto the cylinder

block, and tighten the fixing bolts.

● With the hollow screw, assemble the

oil pipe connected between the oil

cooler and cylinder block.

● Install a connection pipe between the

oil cooler and oil filter.

● Install the oil cooler connecting pipe.

● Install packing and assemble the car-

tridge using a filter wrench.

9.3.26. Injection pump

● Install the injection pump bracket in

the cylinder block.

● After measuring the amount of run-

out with an alignment setting jig, dis-

assemble the bracket, adjust the

shims, then reassemble it.

Run out

0.2 or less

EAMD107I

● Mount the top/bottom adjusting shims

in the bracket and then mount the

fuel injection pump.

● Tighten the fixing bolts in a diagonal

sequence to specified torque.

Torque

4.4 kgm

Disassembly and Reassembly of Major Components - 107 -

● Turn the flywheel until No. 1 piston is

Timing

placed in the

“OT" position of notch

Check hole

marks on the flywheel, and then turn

again the flywheel clockwise until

showing the notch mark of the right

figure corresponding to the injection

timing is aligned with the pointer ( ↓ )

on the flywheel housing.

DE12T /

P126TI /

PU126TI

P126TI-1

P126TI-II

Fuel

injection

timing

12°

16°

14°

Injection timing

Flywheel

(B.T.D.C

notch mark

ring gear

static)

EA8O6002

● Turn the timer until the notch mark of

the indicator plate attached to the fuel

Notch

injection pump is aligned with the

mark

notch mark of the timer.

EA9O5002

● Tighten the Coupling fixing bolts and

nuts to specified torque.

Torque

6.0 kgm

● Tighten the drive shaft connecting

flange fixing bolts to specified torque.

Torque

7.5 ~ 8.5 kgm

● Install the oil delivery pipe and return

EAMD021I

pipe.

108 -

isassembly and Reassembly of Major Components

9.3.27. Vibration damper end pulley

● Install the vibration damper on the

crankshaft pulley.

● Install the crankshaft pulley assembly

on the crankshaft, then tighten the

bolts and thrust washers.

Torque

13.4 kgm

9.3.28. Fan drive pulley

● Install the fan drive pulley onto the

timing gear case cover.

9.3.29. Water pump

● Mount a new O-ring.

● Install the water pump drive pinion

over the PTO (power take-off) spline.

● Connect water pipes and by-pass

pipe to the water pump.

● Connect a water pipe to the expan-

sion tank.

EAMD112I

9.3.30. Power take-off

● Assemble the power take-off sub

assembly.

EA8M3010

Disassembly and Reassembly of Major Components - 109 -

9.3.31. Exhaust manifold

● Install the exhaust manifold gasket over

the stud bolts by aligning the gasket

with the exhaust port on the cylinder

head so that the face and back of the

gasket can be positioned correctly.

● Semi-assemble the exhaust manifold

and install the heat resisting plate.

● First, install the nuts and then place

an additional nut on each of them to

EQM3096I

prevent looseness.

9.3.32. Turbocharger

● Fit a new gasket over the stud bolts

of the exhaust manifold before tight-

ening those turbocharger fixing bolts.

● Install the oil supply pipe and return

pipe.

● Semi-assemble the bracket to the

intake pipe, connect a rubber hose

between the turbocharger and intake

pipe using rubber hose, then assem-

ble the bracket completely.

EA8M3012

9.3.33. Starter

● Assemble the starter in position on

the flywheel housing.

ED5OM009

110 -

isassembly and Reassembly of Major Components

9.3.34. Intake manifold

● Fit a gasket on the intake manifold

before assembling the intake mani-

fold.

EQM3011I

9.3.35. Injection pipe & fuel return pipe

● Assemble the injection pipe according

to specified torque as blow

Nut size

Torque

Spanner Dia. 17 mm

3.0 kgm

Spanner Dia. 19 mm

4.0 kgm

EAMD011I

● Semi-assemble the nuts at both end of

the fuel injection pipe and tighten them

up one by one to specified torque.

Torque

1 ~ 1.5 kgm

● Tighten the hollow screws to assem-

ble the fuel return pipe.

● Assemble the fuel return hose on the

fuel injection pump.

EI6OM015

9.3.36. Fuel filter

● Assemble the fuel filter with the

intake manifold.

● Assemble the fuel feed hose accord-

ing to the direction of an arrow

impressed on the fuel filter head so

that fuel can be fed in the sequence

of FUEL FEED PUMP → FUEL FIL-

TER → FUEL INJECTION PUMP.

EI6OM016

Disassembly and Reassembly of Major Components - 111 -

9.3.37. Cylinder head cover

● Assemble the cover packing with the

cover, install the cover on the head,

then tighten the fixing bolts in

sequence to specified torque.

Torque

2.5 kgm

● Assemble the breather hose with

PCV valve.

EI7OM011

9.3.38. Alternator

● Install the alternator mounting bracket.

● Install the alternator with fixing bolts

to the mounting bracket.

9.3.39. Cooling fan

● Install the cooling fan and flange,

then tighten the fixing boltd.

EQM3106I

9.3.40. V- belt

● Install the V-belt on the crank pulley,

Press here

alternator pulley and fan drive pulley.

15mm

● Adjust the V-belt tension using the

Fan

Alternator

tension adjusting bolt.

Pulley

V-belt

Crank Pulley

EA8O3005

112 -

Disassembly and Reassembly of Major Components

10. Maintenance of Major Components

10.1. Cooling System

10.1.1. General information

This engine is water-cooling type. Heat from the combustion chamber and engine oil heat are

cooled down by coolant and radiated to the outside, resulting in the normal operation of the

engine.

Looking into the cooling system, the water pumped up by the water pump circulates around the

oil cooler through the water pipe to absorb the oil heat, and then flows through the water jacket

of the cylinder block and water passage of the cylinder head to absorb the heat of the combus-

tion chamber.

The water absorbing the oil heat and combustion chamber heat goes on to the thermostat

through the water pipe, and circulates to the water pump if water temperature is lower than the

valve opening temperature on the thermostat, while circulating to the radiator at water tempera-

ture higher than the valve opening temperature. At the radiator, the heat absorbed in the cool-

ant is radiated to cool down and the coolant recirculates to the water pump.

Thermostart

Water pipe

Cylinder head

Cylinder block

Water pump

Oil cooler

ED5OM006

● Specification

Item

Specification

1. Water pump

Centrifugal type

type

Delivery

About 280 liter/min

Pumping speed

2,234 rpm

Pumping back pressure

760 mmHg

2. Thermostat

Operating temperature

71 ~ 85C / 83 ~ 95C

3. Cooling fan and belt

Fan diameter - Number of blades

൵755 - 7

Fan belt tension

15mm / deflection by thumb

114 -

Maintenance of Major Components

10.1.2. Water pump

● Loosen the bolt (16) to disassemble the housing cover (15).

● Heat the impeller (6) slightly, then remove it using a puller jig.

● Remove the mechanical seal.

● Unscrew the socket bolt (12) and remove the shaft and bearing assembly from the housing.

● With a press, remove the spline shaft and bearing.

● Reverse the disassembly sequence for reassembly operation.

● Replace the oil seal (7) with a new one at reassembly.

● To reassemble the impeller, maintain a constant gap (0.3 ~ 0.6 mm) between the impeller

and pump housing using a feeler gauge.

Thickness 0.3 ~ 0.6

Par latex coating

ED5OM007

1. Water pump housing

8. Ball bearing

13. Spline shaft

4. Shaft

9. Spacer

14. Gasket

5. Mechanical seal

10. Ball bearing

15. Housing cover

6. Impeller

11. Bearing cover

16. Bolt

7. Oil seal

12. Socket bolt

Maintenance of Major Components

115 -

10.1.3. Thermostat

● General descriptions and main data

The thermostat maintains a constant tem-

To radiator

perature of coolant

(71 ~ 85C / 83 ~

95C) and improves thermal efficiency of

the engine by preventing heat loss.

Namely, when the temperature of coolant

is low, the thermostat valve is closed to

make the coolant bypass to directly enter

Bypass

valve

the water pump; when the coolant tem-

From cooling

To bypass tube

water pipe

perature rises to open wide the thermo-

EAMC002I

stat valve, the bypass circuit is closed

and the water passage to the radiator is

opened so that the coolant is forced to

flow into the radiator.

Item

Specifications

Type

Wax-pallet type

Open at

71C

83C

Open wide at

85C

Valve lift

8 mm or more

● Inspecting

1) Check the wax pallet and spring

for damage.

2) Put the thermostat in a container of

Ruler

Thermometer

water, then heat the water slowly and

check temperature with a thermome-

ter. If the valve lift is 0.1 mm (starting

Woodplate

to open) at temperature of

71C /

83C and 8 mm or more (opening

wide) at temperature of 85C / 95C,

EFM2055I

the thermostat is normal.

● Replacing thermostat and precautions for handling

1) Precautions for handling

The wax pallet type thermostat does not react as quickly as bellows type one to a varia-

tion of temperature of coolant. Such relatively slow reaction is mainly due to the large

heat capacity of the wax pellet type thermostat. Therefore, to avoid a sharp rise of cool-

ant temperature, it is essential to idle the engine sufficiently before running it. In cold

weather, do not run the engine at overload or overspeed it immediately after starting off.

2) When draining out or replenishing coolant, do it slowly so that air is bled sufficiently from

the entire cooling system.

3) Replacing thermostat

If the thermostat is detected defective, retrace with a new one.

116 -

Maintenance of Major Components

DOOSAN Generator diesel engine DE12T, P126TI, P126TI-1, P126TI-II, PU126TI. Operation and Maintenance Manual - page 3