CROSSHEAD BEARING CLEARANCE

SAFETY PRECAUTIONS

-On FWE get immobilization permission and propeller clearance from bridge.
-under piston spaces and scavenge space ventilate by blower.
-Stopped engine
-Shut off starting air supply At starting air receiver
-Block the main starting valve
-Shut off starting air distributor/distributing system power supply
-Shut off safety air supply
-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
-isolate expansion tank than only drain jacket drain jacket cooling water and open purging valve so that air pressure helps in draining.
CHECKING CROSSHEAD BEARING CLEARANCE 

The top clearance between the journal and a new bearing shell is the result of a summation of the production tolerances of the bearing assembly components.
The top clearance for a new bearing will normally be in the range stated in Data. Note that the figures are to be used for guidance only.
For the top clearance of a specific bearing, see the measurement in the Adjustment Sheet 
1. Open the crankcase door at the relevant
cylinder.
2. Turn the crank throw concerned to BDC.

3. Measure the clearance in the crosshead bearing by inserting a feeler gauge between the bearing cap and the crosshead
journal at the top of the upper bearing shell, at both sides and fore and aft.

4. The difference between the actual clearance measurement and the measurement recorded in the Adjustment Sheet (or the clearance noted for a new bearing installed later) must not exceed 0.1 mm. If so, the crosshead bearing must be disassembled
for inspection. For evaluation of the bearing shell, check my blog.
5. The wear limit for a crosshead bearing shell is confined to a 50% reduction of the oil wedge length L. If the wear limit exceeds the 50% reduction, the bearing shell must be replaced by a new one.

CRANKPIN BEARING CHECKING and DISMANTLING

SAFETY PRECAUTIONS

-On FWE get immobilization permission and propeller clearance from bridge.
-under piston spaces and scavenge space ventilate by blower.
-Stopped engine
-Shut off starting air supply At starting air receiver
-Block the main starting valve
-Shut off starting air distributor/distributing system power supply
-Shut off safety air supply
-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
-isolate expansion tank than only drain jacket drain jacket cooling water and open purging valve so that air pressure helps in draining.

CRANKPIN BEARING CHECKING
The bottom clearance between the journal and a new bearing shell is the result of a summation of the production tolerances of the bearing assembly components.
For the bottom clearance of a specific bearing
1. Open the crankcase door at the relevant
cylinder.
2. Turn the crank concerned to BDC.
3. Measure the clearance in the crankpin
bearing by inserting a feeler gauge at the
bottom of the bearing shell in both sides.
See Data for bottom clearance.

4. The difference between the actual clear-
ance measurement and the measurement
recorded in the Adjustment Sheet (or the
clearance noted for a new bearing installed
later) must not exceed 0.1 mm. If so, the
crankpin bearing must be disassembled for
inspection.
5. The wear limit for the crankpin bearing
shells is based on an evaluation of the
bearing condition at the time of inspection.
An average wear rate of 0.01 mm per
10,000 hours is regarded as normal.

6. For further external inspection of the crank-pin bearing, see .

Now DISMANTLING OF CRANKPIN BEARING;

1. Turn the crank to BDC.
2. Suspend two tackles from the lifting brackets, in the athwartship direction.

3. Turn the crank to TDC.
Mount eye bolts in each side of the crank-
pin bearing cap and, using shackles and
wire ropes, hook on the tackles and haul
tight.Loosen the crankpin bearing stud nuts, using the hydraulic jacks.
Remove the hydraulic jacks and the nuts.

4. Lower the bearing cap while seeing care-
fully that the studs do not damage the
crankpin journal.Land the bearing cap on a couple of planks placed in the oil pan.
Inspect the bearing shell.
For evaluation of bearings, see.

5. If the bearing shell needs to be replaced,
remove the whole bearing cap from the
crankcase.Hook the tackle on to an eye bolt on one side of the bearing cap.
Mount the wire guide in the top of the
crankcase door opening.
Using the tackle from the frame box inside
wall, together with a tackle suspended from
the platform bracket, lift the bearing cap
out of the crankcase.

6. Place the bearing cap on one side on a
couple of planks.
Dismount the bearing shell lock screws and
replace the bearing shell by a new one.

7. Turn to TDC.
Mount the four supports for guide shoes
on the crosshead guides.
Carefully turn the crank down until the
guide shoes rest on the supports.
Adjust the support brackets to the guide
shoes so that the weight of the crosshead
is evenly distributed on the four supports.

8. Mount a lifting attachment for securing the connecting rod at the lower end, on one
side.Hook on the tackle to a beam under the
gallery platform and haul tight.

9. Carefully turn the crankshaft downwards,while ‘following’ with the tackle, making sure that the upper part of the bearing comes completely clear of the recess in the crankshaft when the parts begin to ‘separate’.
Continue turning the crankshaft until the
bearing surface can be freely inspected.
Inspect the bearing shell surface and the
crankpin journal.

10. If it is necessary to replace the bearing
shell, proceed as follows:
Turn the crankshaft to HORIZONTAL.
Release the tackle so that the connecting
rod is hanging freely.

11. Mount an eye bolt in the bottom of each
guide shoe.
Suspend two tackles from the eye bolts.

12. Place the lifting tool for the crankpin upper shell on the crank webs and hook the tackles on to the lifting tool.
Mount the tool on the bearing shell in the
connecting rod, using the tackles, and haul
tight.

13. Dismount the bearing shell lock screws.
Lower the lifting tool with the bearing shell,
using the tackles.

OVERHAULING OF CONNECTING ROD FROM main engine on ship

SAFETY PRECAUTIONS

-On FWE get immobilization permission and propeller clearance from bridge.
-under piston spaces and scavenge space ventilate by blower.
-Stopped engine
-Shut off starting air supply At starting air receiver
-Block the main starting valve
-Shut off starting air distributor/distributing system power supply
-Shut off safety air supply
-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
-isolate expansion tank than only drain jacket drain jacket cooling water and open purging valve so that air pressure helps in draining.

This procedure applies to the overhauling of connecting rod following two dismantling situations:

• with piston mounted
• with piston removed

With piston mounted:
1. Turn the crankshaft down far enough to give access to the nuts and screws on the piston rod.

2. Mount two chains in the inner screw holes in the top of the crankcase, in the athwarthship direction, for suspending the piston rod.

3. Loosen and remove the locking wire from the screws on the piston rod foot. Remove the screws.

4. Mount a lifting eye bolt on each side of the piston rod.

 

5. Turn the crosshead to TDC.
Hook the chains to the lifting eye bolts in the piston rod. Turn the crosshead downward, and the piston rod will then remain suspended from the two chains.

With piston removed:

6. Turn to BDC.
7. Place the spacer rings around the nuts and screw the hydraulic jacks on to the studs.Loosen the crosshead bearing cap nuts.For operation of the hydraulic jacks Remove the hydraulic jacks and the spacer rings, and unscrew the nuts.

8. Mount the lifting attachments on the head of the connecting rod.

9. Suspend two tackles from the lifting brackets,in the athwarthship direction.

10. Mount the wire guide at the top of the crankcase door frame to prevent damage.Mount two eye bolts in the top of the crosshead bearing cap.
Hook the tackles on to the eye bolts, and remove the bearing cap from the engine.Check the upper part of the journal.

11. Place the bearing cap on one side on a couple of wooden planks. Check the bearing shell.

12. Fasten tackles to the fixed lifting brackets on the frame box wall.

13. Turn the crosshead upwards until the piston rod lands on the crosshead. Ensure that the guide ring in the crosshead fits correctly in the centre hole of the piston rod.Do not remove the chains or lifting eye bolts.

14. Turn to TDC and attach the tackle hooks to the lifting attachments. Haul the tackles tight.

15. Mount the four supports for guide shoes on the crosshead guides. Carefully turn the crank down towards the exhaust side, until the guide shoes rest on the supports. Adjust the support brackets to the guide shoes so that the weight of the crosshead is evenly distributed on the four supports. Haul the tackles tight.

16. Turn the crankthrow carefully towards BDC while ‘following’ with the tackles, thus continuously supporting the connecting rod.

17. With the crosshead resting on the supports,check the lower part of the crosshead journal and the lower bearing shell. 
18. In cases where it is necessary to remove the lower bearing shell, tilt the connecting rod towards the doorway on the camshaft side, using the tackles.

Dismount the locking screws, and turn the bearing shell so far up that an eye bolt can be removed                              Lift the bearing shell out of the engine.

Reasons for fuel oil purifier overflow on ship

Overflowing means oil in water this can be because of several reasons they are as follows;

1. Temperature of the oil. Temp should not be high else water will evaporate and due to this interface will break and purifier start overflowing.
2. size of the gravity disc If the size of the gravity disc is more the oil will leak to the waterside.
3. high throughout is the fuel taken in the purifier is capacity is more in the oil may leak to the water side.
4. Operating water level in Tank low or operating water filter chock .The operating water is used for closing and opening of the the bowl by discharge slide and operating slide. If the operating water is not there , than  the bowl will not be closed by closing water than sludge port will be opened slighlty thus oil can leak to water side due to disturbance in the oil -water interface.
5. Sealing water is not present in purifier. As Marine fuel oil normally contains a small amount of water it is necessary to prime the bowl each time that it is run,otherwise the oil will pass over the water outlet side as waste
6. Seal ring is damaged.The bowl is kept closed by the discharge slide, which seals against a seal ring in the bowl hood.if this gets damaged no sealing will be there and sludge port will be opened slighlty thus oil can leak to water side due to disturbance in the oil water interface.
7. By mistake if bowl opening water is  feeded.
8. The o ring is not sealing properly that was near to the plug and nozzle.The oring is present in discharge and operating slide. The o ring doest allow the operating water to leak from the operating and discharge slide . If the water leaks than the slide will not open and close properly thus leakage.

Action to be taken ;

1. Check inlet pressure of the fuel oil it should not be high.
2. Adjust back pressure valve. If you give too much fuel  throughout then Water particle will not come in contact with the plate but if increased furthur throughout oil may leak to water side for that reason there was the back pressure valve with which we can maintain the throughout.
3. Temperature adjust according to nomogram if new bunker has different density need to change using nomogram diagram.
4. If still overflowing bowl needs to be opened up clean bowl, change all o ring and Seal ring, drain nozzle, check vertical shaft height and then box up.

OVERHAULING AND ASSEMBLY OF PISTON IN MAIN ENGINE ON SHIP

SAFETY PRECAUTIONS

-On FWE get immobilization permission and propeller clearance from bridge.
-under piston spaces and scavenge space ventilate by blower.
-Stopped engine
-Shut off starting air supply At starting air receiver
-Block the main starting valve
-Shut off starting air distributor/distributing system power supply
-Shut off safety air supply
-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
-isolate expansion tank than only drain jacket drain jacket cooling water and open purging valve so that air pressure helps in draining.

Preparations in the crankcase
1. Access: Open the crankcase door to the cylinder concerned.
Turn the crosshead down far enough to
give access to the piston rod stuffing box
and the piston rod/crosshead connection.

2. Stuffing box:Release the stuffing box by removing the innermost screws from the stuffing 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 piston rod crosshead
 connection:
Remove the screws from the piston rod.

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 liner and pis-
ton cleaning ring to ensure correct re mounting. Remove the piston cleaning
ring.Carefully remove any wear ridges at the topof the cylinder liner. See Procedure

6. Piston lifting tool:
Turn the piston to TDC. The top of the piston is now free of the cylinder liner.
Clean the lifting groove of the piston crown
and mount the lifting tool.

7. Piston lift:
Lift the piston out of the cylinder liner and guide the piston rod foot through the stuffing 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 stuffing box through the opening in the platform. Secure the two support halves with screws and
lower the piston on the support. Check the piston is resting on the piston rod flange.

8. Protect the crosshead bearing:
Place a cover over the opening for the piston rod stuffing box in the bottom of the cylinder unit. Turn the crosshead down far enough to
permit mounting of the protective rubber cover on the crosshead bearing cap. The protective rubber cover is found on tool
panel. The covers must remain in place to protect the crosshead bearing journal from impurities until the piston is remounted.
Clean, measure and recondition the cylinder liner. See Procedure.

1. Piston support:

Place the piston in the support and remove
the piston lifting tool. Clean the piston top and the piston rings.
Piston top template:
-Check that the piston top template is permanently marked with the piston top centre diameter D02 48.
-Check that the centre area C has been marked off, and write the maximum permissible burn away rate on the template.
-Mark the outer part of the template R for ring area, and write the maximum permissible burn away rate for the ring shaped
area. See data D02 49.
 Piston 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 circumference of the piston crown top.If the burn away exceeds the values given in Data, contact MAN Diesel for advice.
Note down the results for later reference.
-Remove the stuffing box. See Procedure 902 2.3.

2. Piston ring dismantling:

Take off the piston rings by means of the ring expanders. If 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.
 -Ring inspection:-fig 2 below

Inspect the rings, one at a time, and note down the results.
-Ring tension:-fig 3

Check the tension of the piston rings, by pressing against them with a wooden stick.
-Ring grooves- axial clearance -fig 4 below

Measure the total clearance between the piston ring and the ring groove. The total clearance must not exceed the value stated
in Data. Measure the clearance at the top (E) and
bottom (F) of the piston ring groove. Total clearance = E + F.
-Uppermost piston ring:fig 5

If possible, measure the depth of the pressure relief grooves with a calliper. The piston rings must be replaced if the radial depth of the grooves has worn down to less than stated in Data D02 46.
 Free ring gap-butt clearance- fig 7 below

Before dismantling the piston rings, measure the free ring gap of all the piston rings.
Radial ring width - for back clearance -fig 8

Measure the radial width of the rings. Note down the results

Ring grooves: fig 9 above

Clean the ring grooves and check them for burn marks or other deformation. Measure the ring grooves with a calliper
gauge, see Data Clearance in piston ring grooves:
The maximum vertical height in a worn ring groove must not exceed the value statedin Data. The groove is also worn out if
there is no chromium layer. If the ring grooves are worn out, the piston crown must be reconditioned, contact MAN
Diesel for advice.

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.

4. Piston rod and cooling pipe:

Remove the screws from the cooling oil pipe flange. 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. Piston crown turning:
Unhook crane from the piston lifting tool, and connect the lifting tool and the crane hook by means of a wire rope. Lift up the piston crown. Fit two eye bolts in the piston skirt and a wire rope between the bolts as shown in the sketch. Install a tackle in a suitable place with sufficient space below for the piston crown. Attach the tackle to the wire rope on the piston crown and carefully turn the piston
crown upside down. Use both cranes if the engine room is equipped with two cranes. Land the piston lifting tool and the piston crown on a sufficient support of wood pieces. Loosen the piston lifting tool and lift the piston crown clear of the tool.

6. Piston 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 clean and inspect all parts of the crown and skirt. If 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 dissolved, clean and inspect the piston crown again.

7. Piston crown assembly:
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 screws to specifi ed torque, see data D02 05. Lock the screws with locking wire, see Procedure 9

8. Piston crown and skirt mounting:
Mount the guide screw to ensure the correct 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 between the piston rod and the piston crown,

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 the piston with oil. The sealing ring test can also be carried out when the piston is resting in the support tool.

9. Sealing ring test:
Mount the pressure testing tool on the piston rod foot. Connect compressed air to the testing tool and fill the piston to 4 5 bar. Close the valve on the testing tool and remove the air connection. The piston must now hold the pressure for minimum 30 minutes.Spray a little soap water on to the surface joints between piston rod/crown/skirt and around the bolt heads to detect leaks.Dry off all soap water.

10. Pressure test:
For this test, the piston must be turned upside down (see next step to turn a complete piston). Fill the piston and piston rod with lubricating oil. Mount the pressure testing tool on the piston rod foot. Pressure test the piston at the pressure stated on the Data
Sheet. Check the contact surfaces of the piston and the sealing rings for tightness. Check that there are no cracks in the piston crown.
Turn the piston upside up and drain out the piston oil.

11. Piston turning:
Lift the piston with the normal lifting tool. Lower the piston rod foot until it is close to the platform. Land the foot on a wooden
block. Lower the piston crown to the platform and land it 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 lifting tool from the piston crown. Attach the lifting bracket to the bottom of the piston rod foot. Hook the crane on to the lifting bracket. Lift the piston rod foot clear of the wooden block. Keep lifting until the piston rod is in a vertical position.

12. Piston completion:
Fit the new piston rings (alternately right hand and left hand cuts, with the ring gaps staggered 180° and with the TOP mark upwards), using the ring expander. When mounting the piston rings, use the ring expanders to prevent unintended deformation of the rings. Do not expand the rings more than necessary. The uppermost ring (CPR ring) must be mounted with the short ring expander. Mount the piston rod stuffing box.

Preparation of piston

1. Preparation of piston:
Check the piston rings and 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 position:
Ensure that the stuffi ng box is correctly positioned 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. Preparation of cylinder liner.

3. Mount the guide ring:
Mount the guide ring in the top of the cylinder liner. The cut outs for the lifting tool must be turned to fi t the piston lifting tool.

4. Stuffing 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. Crosshead position:
Turn the crosshead to a position 45° from TDC (crank web pointing towards exhaust side).

Mounting of piston

6. Mounting of piston:
Coat the O rings of the stuffing box and the piston rod with oil. Coat the piston rings and cylinder liner with cylinder lubricating 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. Protective cover:
Remove the protective rubber cover from the crosshead.

8. Crosshead alignment:
Turn the crosshead almost to TDC, while checking that the guide ring of the crosshead enters the centre hole in the piston
rod. After turning the crosshead fully to TDC, and ensuring that the piston rod has full contact with the crosshead, unscrew the
lifting tool and remove the lifting tool and the guide ring for piston rings.

9. Stuffing box:
Turn down and land the stuffing box on the stuffing box flange. Check that the holes in the stuffing box and stuffing box flange are correctly centered. Tighten the piston rod stuffing box by
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 stuffing box drain pipe. Remove the distance pieces from the piston rod foot.

10. Tightening of the piston rod crosshead
connection:
Mount and tighten the piston rod screws.Tighten the screws to the specified torque and lock with locking wire. See Data. Use either Data D02 02 or Data D02 07.

11. Piston cleaning ring:
Mount the piston cleaning ring in accordance with the scratch mark. If the PC ring is damaged (broken or cracked), it must be
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 the surfaces around the base of the studs and check the O rings on the studs. Mount the cylinder cover studs with the stud setter. Screw the stud down to contact and half a revolution back.

13. Cylinder cover:
Land the cylinder cover on the liner and check the distance that the stud is protruding from the cylinder cover. If necessary,
adjust the distance D01 05 by turning the stud. Tighten the cylinder cover nuts and mount the necessary pipes. See Procedure 901 1.4.

14. Running in:
Smear the piston rod with molybdenum di- sulphide, 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 Slow”Ahead.
Then stop the engine and inspect the piston rod and stuffing box.