902 piston

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Page 1 (2)

MAN B&W Diesel

SAFETY PRECAUTIONS

Data

D01-05 Cylinder cover stud, check distance 148 - 149 mm

D02-01 Test pressure 7 bar

D02-02 Piston rod/crosshead, tightening torque 590 Nm

D02-03 Piston rod/crown, tightening torque 580 Nm

D02-05 Piston skirt, tightening torque 190 Nm

D02-06 Cooling oil pipe, tightening torque 80 Nm

D02-08 Piston ring new, radial width 20.2 mmD02-09 Piston ring worn, min. radial width 17 mm

D02-10 Groove No.1, max. vertical height 14.7 mm

D02-11 Groove Nos. 2, 3 and 4, max. vertical height 11.7 mm

D02-13 Piston ring new, height of ring No. 1 13.9 mm

D02-14 Piston rings new, height of ring Nos. 2, 3 and 4 10.9 mm

D02-15 Minimum free ring gap ( before dismantling ) 30.5 mm

D02-16 Minimum ring gap, ring No. 1 ( new ring in new liner ) 4.1 mm

D02-17 Minimum ring gap, ring Nos. 2, 3 and 4 ( new ring in new liner ) 3 mm

D02-18 Vertical clearance, new parts 0.43 mm

D02-19 Vertical clearance, worn parts, max. 0.92 mm

D02-20 Piston complete 1600 kg

D02-21 Piston crown 310 kg

D02-22 Piston rod 1050 kg

D02-23 Piston skirt 95 kg

D02-24 Piston cooling pipe 36 kg

D02-25 Lifting tool, tightening torque 150 Nm

D02-46 CPR ring CL groove, min. depth 1.3 mm

D02-47 Piston top centre, max. permissible burn-away 9 mm

D02-48 Piston top centre diameter 280 mmD02-49 Piston top outer ring area, max. permissible burn-away 6 mm

Piston

Data

102-1

When referring to this page, please quote Data D10201 Edition 0097

X

For detailed sketch, see 900-2

Stopped engine

Shut off starting air supply At starting air receiver

Block the main starting valve

Shut off starting air distributor/distributing system supplyShut off safety air supply Not ME engines

Shut off control air supply

Shut off air supply to exhaust valve Only with stopped lubricating oil pumps

Engage turning gear

Shut off cooling water

Shut off fuel oil

Stop lubricating oil supply

Lock the turbocharger rotors

Ref. Description Value Unit

X

X

XX

X

X

X

X

X

X

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Page 2 (2)

MAN B&W Diesel

The task-specific tools used in this procedure are shown on the plates at the end of this chapter or in thechapters indicated by the first three digits in the plate number, e.g. P90951refers to chapter 909.

Piston

Data

102-1

When referring to this page, please quote Data D10201 Edition 0097

P90251 40 Lifting tool for piston rod foot

P90251 75 Template for piston top

P90251 87 Distance piece for stuffing box

P90251 99 Cover for stuffing box hole

P90251 110 Pressure test tool for piston

P90251 134 Piston ring expander

P90251 158 Guide screw for piston crown

P90251 171 Dismantling screw piston skirt

P90261 Guide ring for piston

P90265 Support for piston

P90266 Lifting tool for piston

P90366 Crossbar for cylinder liner

Plate Item No. Description

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Page 1 (20)

902-1.1

When referring to this page, please quote Procedure M90201 Edition 0284

MAN B&W Diesel Checking

Piston

M902010

280C03

M902010

280C02

M

902010

280C01

2.

3.

1.Scavenge Port Inspection

To d etec t pos sible leakag es from the pisto n

or cylinder cover, keep the cooling water

and cooling oil circulating during the scav-

enge port inspection.

1. The sca venge port inspection is c arried out

from the scavenge air receiver. An addi-

tional view of the rings is possible through

the cleaning cover on the manoeuvring

side.

Turn the eng ine a t lea st a revolution, a nd

begin with a unit arriving downwards, just

above the scavenge air ports. Inspect the

piston rod and the lower part of the cylin-

der wall.

While the piston is passing downwards, in-

spect the piston skirt, all the piston rings,

the ring lands and the piston top.

2. R ing inspec tion:

Inspect the rings, one at a t ime, and note

down the results. See Volume I, Operation,

Chapter 707.

3. R ing tens ion:Check the tension of the piston rings, by

pressing against them with a wooden stick.

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Piston

Page 2 (20)

902-1.1


MAN B&W DieselChecking

M902010

283C06

M

902010

280C04

D0218

Max. 2mm

E

F

D0219

M902010

280C05

D0246

5.

6.

4.4. Ring g ro ove s :

Measure the tota l c learance between the

pist on ring a nd the ring g roo ve. The to ta l

clearance must not exceed the value stated

in Data.

Measure the clearance at the top (E) and

bottom (F) of the piston ring groove.

Tota l clea ranc e = E + F.

5. Uppermost piston ring:

If possible, measure the depth of the pres-

sure relief g roo ves w ith a ca lliper. The p is -

ton rings must be replaced if the radial

depth of the grooves has worn down to

less than stated in Data D02-46.

Checking, in connection with pistonoverhaul

6. P is to n s up po rt:

Remove the piston from the cylinder and

place it on the piston support.

See Procedu re 902-1.2. For evaluation of

the rings, see Volume I, Chapter 707.

Note!

It is recommended to replace all the pis-

ton rings whenever a piston is removed

from the engine.

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Page 3 (20)

902-1.1


MAN B&W Diesel Checking

Piston

M902010

280C09

D02-10

D02-11

Max 2mm

M902010

280C08

New

Worn

D0208

D0209

M

902010

280C07

D0215

8.

9.

7.7. Fre e ring g a p :

Before dismantling the piston rings, mea-

sure the free ring gap of all the piston

rings.

For dismantling the p iston rings, see Proce-dure 902-1.3.

8. Radia l ring wid th:

Measure the radial width of the rings. Note

down the results See Volume I, Operation,

Chapter 707.

9. Ring g ro ove s:

Clean the ring grooves and check them for

burn marks or other deformation.

Measure the ring grooves with a call ipergauge, see Data D02-10 and D02-11.

Clearance in piston ring grooves:

The ma ximum vertica l height in a w orn ring

groove must not exceed the value statedin Dat a . The g roo ve is a ls o w orn out if

there is no chromium layer.

If the ring grooves are worn out, the piston

crown must be reconditioned, contact MAN

B &W Dies el A/S for a dvice .

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Piston

Page 4 (20)

902-1.1


MAN B&W DieselChecking

M902010

280C11

D0249D0247

M

902010

280C10

D0248

R

C

10. P iston top template:

Check that the piston top template is per-

manently marked with the piston top centre

diameter D02-48.

Check tha t the centre area C h a s b eenmarked off , and write the maximum per-missible burn-away rate on the template.

See data D02-47.

Mark the outer part of the template R fo rring area, and write the maximum permis-sible burn-away rate for the ring shaped

area. See data D02-49 .

11. P iston crown top:

Clean the piston crown and check the

burn-away by means of the template.

For maximum permissible burn away on the

piston top centre area, see Data D02-47.

For the ring shaped area, see Data D02-49.

Check the burn-away on the whole circum-

ference of the piston crown top.

If the burn-away exceeds the values given

in Da ta , c on ta c t MAN B&W for advice.

Note down the results for later reference.

11.

10.

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Page 5 (20)

902-1.1


MAN B&W Diesel Dismantling

Piston

M902010

284D04

M

902012

80D01

Preparations in the crankcase

1. Access :

Open the crankcase door to the cylinder

concerned.

Turn the cros shea d d ow n far enough to

give access to the piston rod stuff ing box

a nd the pisto n rod /cross hea d c onnection.

2. S tuffing b o x:

Release the stuff ing box by removing the

innermost screws from the stuff ing box

flange.

On engine models where the drain pipe is

connected directly to the stuffing box:

Disconnect the stuffing box drain pipe.

3. Loosen the p is ton rod-crosshead connec-

tion:

Remove the screws from the piston rod.

1.

Note!

Do NOT remove the outermost screwsfrom the flange.

M902010

280D03

3.

2.

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Piston

Page 6 (20)

902-1.1


MAN B&W DieselDismantling

M902010

280D05

4. Stuffing box distance pieces:

Mount the two distance pieces on the pis-

ton rod foot to protect the lower scraper

ring and to guide the stuffing box.

Preparations on the cylinder top

5. Cylinder cover:

Remove the cylinder cover. See Procedure

901-1.2.

Make a scratch mark in l iner and piston

cleaning ring to ensure correct re-mounting.

Remove the piston cleaning ring.

Carefully remove any wear ridges at the

top of the cylinder liner. See Procedure

903-1.3.

4.

M902010

2

80D06

5.

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Page 7 (20)

902-1.1



Piston

M

902010

283D07

D0225

6. Piston lift ing tool:

Turn the p is ton to TDC . The top of the p is -

ton is now free of the cylinder liner.

Clean the lifting groove of the piston crown

and mount the lifting tool.

Limited lifting high:

If the engine not is equipped with long dis-

tance pieces, remove one or two cylinder

cover studs, using a stud setter.

6.

Note!

Make sure to mount the lifting tool cor-

rectly, so that the claws of the lifting tool

enter the lifting grooves of the piston

crown.

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Piston

Page 8 (20)

902-1.1


MAN B&W DieselDismantling

Piston lift

7. Lift the pisto n out of the cylinder liner a nd

guide the piston rod foot through the stuff-

ing box flange.

If the engine is equipped with long distance

pieces for the stuffing box, the piston rod

foot can pass between two cylinder cover

studs.

Place the two halves of the support around

one of the openings in the platform. Lower

the piston rod foot and stuff ing box

through the opening in the platform. Secure

the two support ha lves wi th screws and

lower the piston on the support. Check the

piston is resting on the piston rod flange.

7.

D0220

M90201

0283D08

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Page 9 (20)

902-1.1



Piston

M902010

283D09

8. Protec t the c rosshead bearing :

Place a cover over the opening for the pis-

ton rod stuff ing box in the bottom of the

cylinder unit.

Turn the cros shea d d ow n far enough to

permit mounting of the prote ctive rubb er

co ver on the cross hea d b ea ring c a p. The

protective rubber cover is found on tool

panel 904.

The c overs must rema in in pla ce to protec t

the crosshead bearing journal from impuri-

ties until the piston is remounted.

Clean, measure and recondition the cylin-

der liner. See Procedure 903-1.

8.

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Piston

Page 10 (20)

902-1.1


MAN B&W DieselOverhaul

M902010

284O03

D0221

+

D0223

M902010

280O02

M

902010

280O01

D0220

1. P is to n s up po rt:

Place the piston in the support and remove

the piston lifting tool.

See Procedure 902-1.2.

Clean the piston top and the piston rings.

Check the free ring gap and the burn-off

on the piston top. See Procedure 902-1.1.

Remove the stuff ing box. See Procedure

902-2.3.

2. Piston ring dismantling:

Ta ke off the pis ton rings by mea ns of the

ring expanders. I f the engine is equipped

with two ring expanders, the short ring ex-

pander is for the uppermost ring.

First remove the uppermost ring, then ring

No. two, three and four.

Clean and inspect the rings and the ring

grooves. See Procedure 902-1.1.

3. Piston crown dismantling:

Remove the locking wire and the innermost

screws between the rod and the piston

crown.

Lift the piston crown and skirt clear of the

piston rod.

2.

1.

3.

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Page 11 (20)

902-1.1


MAN B&W Diesel Overhaul

Piston

M902010

284O05

D0223

M

902010

280O04

D0206

D0224

D0222

4. P iston rod and cooling pipe:

Remove the screws from the cooling oil

pipe fla nge.

Mount the eye bolts and lift out the cooling

oil pipe.

Clean and inspect the cooling oil pipe and

the piston rod, then remount the cooling oil

pipe, see Data.

Check that the surfaces of the O-ring

groove is clean and smooth.

Mount a new O-ring on the piston rod

flange.

5. P iston crown dismantling and cleaning:Place the piston crown with skirt on a

wooden support as shown.

Remove the locking wire and the screws in

the skirt. If necessary use two dismantling

screws to pull the skirt out of the piston

crown. Mount two eye bolts in the skirt. Lift

the skirt and land it on a couple of planks.

Discard the sealing ring on the piston skirt.

Thoroughly clea n and ins pec t all pa rts of

the crown and skirt . I f coke deposits are

found in the cooling spaces of the piston

crown, they should be washed clean with

Carbon Remover or a similar cleaning fluid.

When all coke deposits have been dis-

solved, clean and inspect the piston crown

again.

5.

4.

Note!

Coke deposits reduce heat transfer fromthe pisto n crow n to the c oo ling oil. The

deposits must be removed as a routine

procedure when a piston is overhauled.

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Piston

Page 12 (20)

902-1.1



M902010

284O07 D0203

M

902010

284O06

D0205

6. P is ton c row n a s semb ly :

Mount a new O-ring on the piston skirt.

Check that the surfaces of the O-ring

groove are clean and smooth. Coat the ring

with lubricating oil before mounting.

Mount the piston skirt on the piston crown.

Tighten the s crews to s pec ified torq ue, see

data D02-05. Lock the screws with locking

wire, see Procedure 913-7.

7. Piston crown and s kirt mounting:

Mount the guide screw to ensure the cor-

rect positioning of the piston rod in relation

to the piston crown.

Lubricate the O-ring on the piston rod

flange with lubricating oil.

Land the overhauled piston crown and skirt

on the piston rod.

Remove the guide screw.

Mount and tighten the screws betw een the

piston rod and the piston crown, see Data.

7.

6.

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Page 13 (20)

902-1.1



Piston

M

902010

277O16

M902010

277O17

o

D0201

Sealing ring and pressure test

According to current class rules, the piston

must be pressure tested hydraulically. It is

possible to carry out a test of the sealing

rings with compressed air before filling thepis ton w ith oil. The s ea ling ring tes t c a n

also be carried out when the piston is rest-

ing in the support tool.

8. S ea ling ring t e s t:

Mount the pressure-testing tool on the pis-

ton rod foot . Connect compressed a ir to

the testing tool and fill the piston to 4-5

bar. Close the valve on the testing tool and

remo ve the a ir co nnec tion. The pisto n must

now hold the pressure for minimum 30

minutes.

Spray a little soap water on to the surface

joints b et w ee n pis to n rod /c row n/s kirt a nd

around the bolt heads to detect leaks.

Dry off all soap water.

9. P re s sure te s t:

For this test, the piston must be turned up-

s ide down (see next step to turn a com -

plete p iston).

Fill the piston and piston rod with lubricat-

ing oil. Mount the pressure-testing tool on

the piston rod foot. Pressure-test the pis-

ton a t the pressure sta ted on the Data

Sheet . Check the contac t surfaces of the

piston and the sealing rings for tightness.

Check that there are no cracks in the pis-

ton crown.

Turn the pis ton ups ide up a nd d rain out the

piston oil.

9.

8.

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Piston

Page 14 (20)

902-1.1



M902010

283O10

10. P iston turning:

Lift the piston with the normal lifting tool.

Lower the piston rod foot until it is close to

the pla t form. Land the foot on a wooden

block.

Lower the piston crown to the platform and

land i t on a wooden block in such a way

that it is possible to remove the lifting tool.

Mount an eyebolt in the side of the lifting

tool, hook on the crane and remove the lift-

ing tool from the piston crown.

Attach the lifting bracket to the bottom of

the piston rod foot. Hook the crane on to

the lifting b ra cket. Lift the pis ton rod fo ot

clear of the wooden block. Keep lifting untilthe piston rod is in a vertical position.

10.

Note!

During the lift, follow with the crane to

keep the crane positioned vertically

a bo ve the lifting po int. The s tuffing bo x

must be removed.

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Page 15 (20)

902-1.1



Piston

M902010

280O11

TOP

A

B

C

D

A

B

C

D

11.11. P iston completion:

Fit the new piston rings (alternately right-

hand and left-hand cuts, with the ring gaps

sta gg ered 180 a nd w ith the TOP ma rk up-

wards), using the ring expander.

When mounting the piston rings, use the

ring expanders to prevent unintended de-

formation of the rings.

Do not expand the rings more than neces-

s a ry. The upp ermo s t ring (C P R-ring ) mus t

be mounted with the short ring expander.

Mount the piston rod stuffing box.


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Piston

Page 16 (20)

902-1.1


MAN B&W DieselMounting

M90201

0283M01

M902010

277M02

Preparation of piston

1. Check the piston rings a nd piston crown in

accordance with Procedure 902-1.1,if not

already done.

Mount the lifting tool on the piston crown.

See Data D02-25.

2. Stuffing box posit ion:

Ensure that the stuffing box is correctly po-

sitioned over the distance pieces mounted

on the piston rod foot. Both the holes for

the flange and the drain hole for the drain

pipe must be positioned correctly.

2.

1.

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Page 17 (20)

902-1.1


MAN B&W Diesel Mounting

Piston

M

902010

283M03

M902010

277M06

45

M902010

277M05

Preparation of cylinder liner

3. Mount the guide ring:

Mount the guide ring in the top of the cyl-

ind er liner. The c ut outs for the lifting to o l

must be turned to fit the piston lifting tool.

4. S tuffing box cover:

Remove the cover from the piston rod

stuffing box opening in the bottom of the

cylinder unit.

Clean the stuffing box flange.

5. Crosshea d p os ition:

Turn the c ros she a d to a pos ition 45 from

TDC (crank we b po inting to w a rds exha ust

side).

4.

3.

5.

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Piston

Page 18 (20)

902-1.1



M902010

284M08

M902010

283M07

M

902010

283M06

D0220

Mounting of piston

6. Coa t the O-rings o f the s tu ff ing box and

the piston rod with oil . Coat the piston

rings and cylinder liner with cylinder lubri-

cating oil.

Lower the piston into the cylinder liner

while guiding the piston rod foot through

the cut-out in the stuffing box flange until

the piston rings are inside the liner.

7. P ro tec tive c over:

Remove the protective rubber cover from

the c ross head.

8. Crosshea d a lignm ent:

Turn the cros s hea d a lmo s t to TDC , w hilechecking that the guide ring of the cross-

head enters the centre hole in the piston

rod.

After turning the c ros s hea d fully to TDC ,

and ensuring that the piston rod has full

contac t wi th the crosshead, unscrew the

lifting tool and remove the lifting tool and

the guide ring for piston rings.

6.

7.

8.

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Page 19 (20)

902-1.1


MAN B&W Diesel Mounting

Piston

M902010

284M10

D0202

or

D0207

M902010

277M14

9. S t uffing b o x:

Turn do w n a nd land the s tuffing b ox o n the

stuffing box flange. Check that the holes in

the stuffing box and stuffing box flange areco rrec tly ce ntered .

Tig hten the p is ton rod s tuffing b ox b y

means of the screws through the inner

holes in the stuffing box flange. For Data,

see Procedure 902-2.

On engine models where the drain pipe is

connected directly to the stuffing box:

Mount the stuff ing box drain pipe.

Remove the distance pieces from the pis-

ton rod foot.

10. Tightening o f the pisto n rod -cros she a d

connection:

Mount and tighten the piston rod screws.

Tig hten the sc rew s to the s pec ified to rq ue

and lock with locking wire.

See Data. Use either Data D02-02 or Data

D02-07.

11. P iston cleaning ring:

Mount the piston cleaning ring in accor-

dance with the scratch mark. If the PC-ring

is damaged (broken or cracked), it must be

M

902010

280M09

10.

9.

11.

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Piston

Page 20 (20)

902-1.1



M

902010

277M15

M902010

280M14

D0105

12.

13.

replaced by another ring.

See Procedure 903-1.

12. Cylinder cover studs :

If the cylinder cover studs have been re-

moved, remount them. Carefully clean thesurfaces around the base of the studs and

check the O-rings on the studs.

Mount the cylinder cover studs with the

stud set ter . Screw the stud down to con-

tact and half a revolution back.

13. Cylinder cover:

Land the cylinder cover on the liner and

check the distance that the stud is protrud-

ing from the cylinder cover. If necessary,

adjust the distance D01-05 by turning thestud.

Tig hten the cylinde r cove r nuts a nd m ount

the necessary pipes.


14. Running-in:

Smear the piston rod with molybdenum

disulphide, and turn the crankshaft a

couple of revolutions.

At the first opportunity, start the engine

and keep it running for about 15 minutes at

a speed corresponding to Dead S low

Ahead.

Then sto p the eng ine a nd insp ect the pis-

ton rod and stuffing box.

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Page 1 (2)

SAFETY PRECAUTIONS

Data

D02-26 Stuffing box flange, outer screws tightening torque 80 Nm

D02-27 Stuffing box flange, inner screws tightening torque 80 Nm

D02-28 Stuffing box halves, tightening torque 80 Nm

D02-29 Uppermost rings, ring-end clearance 4x6 mm

D02-30 Lowermost rings, ring-end clearance 3x3 mm

D02-34 Sealing ring springs new, free length 618 mmD02-38 Scraper ring springs new, free length 606 mm

D02-44 Stuffing box complete 100 kg

D02-45 Stuffing box half 35 kg

D02-50 Stuffing box halves fitted bolts, tightening torque 25 Nm

Piston Rod Stuffing Box

Data

102-2

When referring to this page, please quote Data D10202 Edition 0060MAN B&W Diesel A/S

X

X

X

XX

X

X

X

X

X

X

For detailed sketch, see 900-2

Stopped engine

Shut off starting air supply At starting air receiver

Block the main starting valve

Shut off starting air distributor/distributing system supplyShut off safety air supply Not ME engines

Shut off control air supply

Shut off air supply to exhaust valve Only with stopped lubricating oil pumps

Engage turning gear

Shut off cooling water

Shut off fuel oil

Stop lubricating oil supply

Lock the turbocharger rotors

Ref. Description Value Unit

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Page 2 (2)

The task-specific tools used in this procedure are shown on the plates at the end of this chapter or in thechapters indicated by the first three digits in the plate number, e.g. P90951refers to chapter 909.

Piston Rod Stuffing Box

Data

102-2

When referring to this page, please quote Data D10202 Edition 0060MAN B&W Diesel A/S

P90251 109 Mounting tool for stuffing box spring

P90251 122 Worktable for stuffing box

P90451 120 Rubber cover for crosshead

Plate Item No. Description

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Page 1 (10)

Piston Rod Stuffing BoxChecking

902-2.1

When referring to this page, please quote Procedure M90202 Edition 0229MAN B&W Diesel A/S

M902020

227C02

D0234

D0238

M902020

229C01

D0229

D0230D0229

D0230

A B

A

B

2.

1.1. After the piston rod s tuff ing box has been

dismantled, check the following clearances:

See Proced ure 902-2.2.

Uppermost scraper ring and sealing rings

Clearance at ring ends (scraper ring).

Tota l clea rance (sc rap er ring ). (D02-29)

Clearance at ring ends (sealing rings).

Tota l clea rance (sea ling rings ). (D02-29)

Lowermost scraper rings

Clearance at ring ends.

Tota l c lea rance. (D02-30)

The ring c lea ra nce s s ta ted in Da ta a pply to

new rings.

As a general guide, i t is recommended

depending on the overhauling intervals and

ones own experience to replace sealing

rings and scraper rings when the specified

clearance values D02-29 and D02-30 have

been halved.

2. G arte r sp rings :

Generally, it is recommended to renew the

springs when the sealing rings and scraper

rings are renewed.

The springs ca n be chec ked a s follow s:

Place the springs on the table, measure Lo

(free length), and compare with Data. If a

spring is extended more than 8% from the

value given in data, it must be discarded.

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Piston Rod Stuffing BoxDismantling

Page 2 (10)

902-2.2


M90202

022

9D03

M90202

0229D02

M90202

0229D01

2.

3.

1.In connection with dismantling of the piston,

only the innermost screws in the stuffing box

flange and the screws for the drain oil pipe

should be removed.

If, in the period between piston overhauls, itbecomes necessary to inspect the piston rod

stuffing box, proceed as follows:

1. Turn the crosshead to a bout 90 from TDC.

Mount the rubber cover around the piston

rod to protect the crosshead bearing from

impurities.

2. Remove the drain oil pipe and a ll innermost

screws and all outer screws except for two

screws placed diametrically opposite in thestuffing box flange, longitudinally to the en-

gine.

3. Mount the worktable around the piston rod

so that the two remaining screws in the

stuf f ing box f lange can be loosened

through the holes.

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Page 3 (10)

Piston Rod Stuffing BoxDismantling

902-2.2


M902020

229D06

M902020

229D05

M90202

0229D04

5.

6.

4.4. Remov e th e tw o lon g d ism an t lin g s c rew s

from the worktable.

Mount them in the stuffing box through the

holes in the worktable.

Remove the remaining two screws from the

stuffing box.

5. Turn the piston to BDC , thereby withdraw -

ing the stuffing box from the cylinder frame

bottom.

6. Remov e th e tw o lon g d ism an t lin g s c rew s

from the stuff ing box and mount them in

the worktable.

By means of the four short screws in theworktable, press the stuffing box out of the

flange.

For overhauling th e stuff ing b ox, see Pro-

cedu re 902-2.3.

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Piston Rod Stuffing BoxOverhaul

902-2.3


Page 4 (10)

M902020

229O03

M902020

229O02

D0244

Normally, overhaul of the piston rod stuffing

box is carried out by routine methods in con-

nection with the dismantling (pulling) of the pis-

tons.

During such overhauls, the piston rests on asupport placed over one of the cut-outs in the

top platform.

Work on the s tuffing bo x is then c a rried out

from the platform below.

Overhaul inside the engine is carried out in the

same way as outside the engine.

1. Mount two eye bolt s in the s tuff ing box

flange, and hook on two tackles.

Lift the stuffing box a little up the piston

rod, and mount the worktable round the

piston rod at a suitable working height.

Land the stuff ing box on the worktable,

and remove the tackles and eye bolts.

2. Remove the O-rings o f the s tuff ing box. If

the O-rings are intact and are to be used

again , move them up the piston rod and

secure them in this position, for examplewith tape.

Remove the nuts from the stuffing box as-

sembling bolts.

1.

2.

M90202

0229O01

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Page 5 (10)


902-2.3


M902020

229O08

M902020

227C02

D0234

D0238

M

902020

229O04

D0245

3. Take out the s ix bolts , and pull a wa y one

stuffing box half.

Mount two eye bolts on the stuff ing box

half and remove it from the worktable.

4. Using a feeler ga uge, meas ure the vert ica l

clearance of the rings.


5. Remove the remaining stuff ing box half and

press all sealing rings and scraper rings

down against the worktable.

6. Measu re the c lea ran ce b e tw een the rin g

segments to determine whether replace-

ment is neces sa ry.


Dismantle and stack the rings in the same

order as when fitted in the stuffing box.

Ca refully c lea n a ll the ring se gme nts.

Inspect and assess the surface qual i ty of

the sealing rings. If their sliding surfaces

have s cratches or marks, repla ce the rings.

7. Check the lengths of the springs.See Proced ure 902-2.1.

8. Inspect the surf ace o f the p is ton rod . If

small longitudinal scratches have occurred

(caused by poorly adapted stuf f ing box

rings), smooth the piston rod surface care-

fully with a fine grained carborundum

stone. In the case of coarse scratches, i t

may prove necessary to machine-grind the

surfac e in a wo rkshop.

9. Clean the halves of the s tuff ing box hous-

ing.

3.

7.

8.

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902-2.3


Page 6 (10)

M90202

0229

O10

A

B

C

Scraperring

Scraperring

Sealingring

No reliefgroove

Reliefgroove

A

B

C

10. Lubric a te the pisto n rod (in the area w here

all the ring units in the stuffing box will be

positioned) with molybdenum disulphide

(MoS2).

For correct mounting of the sealing andsc ra per rings se e the s ketch. The s crape r

ring in groove no. 4 must be without relief

grooves on the underside.

10.

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Page 7 (10)


902-2.3


M902020

229O12

M

902020

229O11

11. Ass emb le a ll the s tuff ing bo x ring units

round the piston rod, on the worktable, in

the following way:

P lac e the low erm os t s c rap er rin g seg-

ments on the worktable.

P lac e the sp rin g roun d th e segm en ts ,

and hook the spring ends together.

Repeat this procedure for the remaining

scraper rings.

On top of the scraper rings, assemble the

two sealing ring units (each consisting of a

4-part and an 8-part ring).

Assemble the 8-part sealing ring so thatthe two guide pins face upwards, place the

spring round the segments and, hook the

spring ends together.

Assemble the 4-part sealing ring above the

8-part sealing ring. Push the two rings to-

gether in such a manner that the guide

pins in the lower sealing ring engage with

the two holes in the upper sealing ring.

Finally, assemble the uppermost ring unit(consisting of a 4-part scraper ring and an

8-part sealing ring).

12. Use the s tuffing bo x ha lf on the workta ble

to adjust the height of al l the assembled

ring units on the piston rod until the ring

units are opposite the corresponding

grooves in the stuffing box housing. Subse-

quently, push the stuffing box half into con-

tact with the piston rod, round the ring

units.

Note!

If the stuffing box is assembled inside

the engine, place two pieces of plywood

of the same thickness as the flange on

the worktable, to ease the assembling.

11.

12.

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902-2.3


Page 8 (10)

M902020

229O14

D0244

M90202

0229O13

D0228

D0250

13. Check the ring c learance a ga in.

Then plac e the othe r half of the s tuffing

box housing on the worktable, pushing i t

into place round the rings.

In the middle holes mount and tighten up

the f i t ted bolts to the torque specif ied on

the Data Sheet, See Data D02-50

Mount the O-rings in the stuffing box

grooves.

14. Mount eye bo lts a nd w ire ropes, a nd l if t

the stuffing box a little.

Remove the worktable and lower the stuff-

ing box until i t rests against the distancepieces on the piston rod foot.

Remove wire ropes and screws.

Mount and t ighten the s tandard bol ts to

specified torque, See Data D02-28

13.

14.

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Page 9 (10)

Piston Rod Stuffing BoxMounting

902-2.4


M

902020

229M01

M902020

229M03

M902020

229M02

1. In connection with mounting of the piston,

only the innermost flange screws are to be

mounted and tightened, see data.

After overhauling the stuffing box inside the

engine, assemble the stuff ing box halveson top of the four screws.

Mount the two long screws from the work-

table in the stuffing box.

Turn do wn the s hort sc rew s s o tha t the

stuffing box lands on the flange.

2. Turn the pisto n upwa rds until the stuffing

box is in place in the cylinder frame.

3. Mount two screws in the flange through the

holes in the worktable.

Note!

Make sure that the two guide pins in the

flange enter the guide holes in the bot-

tom of the cylinder frame.

1.

2.

3.

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902-2.3


Page 10 (10)

M90202

022

9D01

M902020

229M05

D0226

D0227

M

902020

229M04

4.

5.

6.

4. Remove the long sc rews f rom the stuff ing

box and mount them itheworktable.

Remove the worktable from the piston rod.

5. Mount the drain oil pipe.

Mount and tighten all the inner and outer

screws for the stuffing box. See Data.

6. Remove the protec t ing rubber cover f rom

the pisto n rod /cross hea d.

Smear the piston rod with molybdenum

disulphide.

Then turn the c ra nksha ft a c ouple of revo-

lutions.

If possible: Start up the engine and keep it

running for about fifteen minutes at a num-

ber of revolutions corresponding to very

slow or idle speed.

Then sto p the eng ine a nd insp ec t the pis-

ton rod and stuffing box.

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Plate

Page 1 (2)When referring to this page, please quote Plate EditionMAN B&W Diesel A/S

Piston and Piston Rod PanelP90251-0246

P90251 0246

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Plate

Page 2 (2) When referring to this page, please quote Plate EditionMAN B&W Diesel A/S

P90251-0246Piston and Piston Rod Panel

ItemNo.

Item DescriptionItemNo.

Item Description

P90251 0246

014 Panel for tools

026 Name plate

040 Lifting tool for piston rod foot

051 Lifting tool for cylinder liner075 Template for piston top087 Distance piece for stuffing box

099 Cover for stuffing box hole

109 Mounting tool for stuffing box spring110 Pressure test tool for piston122 Worktable for stuffing box

134 Piston ring expander

158 Guide screw for piston crown183 Pulling tool for stuffing box

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Plate


Piston and Piston Rod - ToolsP90261-0107

P90261 0107

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Plate


P90261-0107Piston and Piston Rod - Tools

ItemNo.


Item Description

P90261 0107

019 Guide ring for piston

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Plate


Piston and Piston Rod - Support ToolsP90265-0005

P90265 0005

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Plate


P90265-0005Piston and Piston Rod - Support Tools

ItemNo.


Item Description

P90265 0005

010 Support iron for piston

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Plate


Piston - Lifting ToolsP90266-0002

P90266 0002

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PlateP90266-0002

Piston - Lifting Tools

ItemNo.


Item Description

016 Lifting tool for piston

902 piston

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