Phone: (052) 262 80 10 (24hours)

Diesel After-Sales Service

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New Sulzer Diesel LtdTelex: 896 659 NSDL CHDiesel After-Sales Service

Telefax: (052) 213 94 83PO Box 414 CH-8401 Winterthur, Switzerland

Service Bulletin A – 3.1 Technical Information to all the Ownersof Sulzer A Type Diesel Engines

Grinding of Inlet / ExhaustValves and Seats

22.03.96(Supersedes Bulletin A–3 dated 12.09.83)

Contents: Page

– INTRODUCTION 1

– 1. RE-GRINDING OF INLET 1AND EXHAUST VALVES

– 2. RE-MACHINING OF INLET 2AND EXHAUST VALVE SEATSIN THE CYLINDER HEAD

– 3. TURNING OF VALVE SEATS 4ON MDO-ENGINES

– 4. SERVICE BULLETINS 5PUBLISHED FORA-TYPE DIESEL ENGINES

1 / 5 Service Bulletin A-3.1

INTRODUCTION

This Service Bulletin deals with the grinding of inlet and exhaust valves and seats of A�Typediesel engines.

Service experience has shown that some difficulties were encountered with reconditioning ofvalves and valve seats. This Service Bulletin informs about the latest procedure for regrindingvalves and seats.

The handling and operation of the grinding tool is described in the manual supplied with thegrinding machine and should be carefully observed.

This Service Bulletin should be kept in a separate file in the control room. The respective pages ortables of the Service Bulletin with modifications to the Operating Manual, Maintenance Manualor Code Book should be copied and filed in the respective Manual or Book.

1. RE-GRINDING OF INLET AND EXHAUST VALVES

Lapping�in the valve to the valve seat using lapping paste is to be avoided. Lapping�in of aNimonic exhaust valve with its valve seat using lapping paste can lead to damage.

Valves whose seating surface is badly damaged by pitting and corrosion have to be regroundusing a suitable machine tool.

Seating surface angle on the valve = 30° 0- 2'

When grinding, only a minimum of material should be removed, just enough to obtain a smoothsurface, in order to prolong the usable lifetime of the valve.

Grind only with wet cooling.

In order to prevent chatter marks on the seating surface, the grinding machine has to be situatedat a place where it will not be influenced by vibration of any machinery. If necessary, thegrinding machine has to be mounted on rubber pads.

Unarmoured valves may be reground to a maximum until the seating surface is at the same levelas the valve head. (see A�3.1 / 1, Fig. A, dimension "a").

Armoured valves may be reground to a minimum of 5 or 4 mm of the valve edge heightdepending on the valve diameter (see A�3.1 / 1, Fig. B).

When the angle has been accurately maintained during grinding, a marking check of thereground valve together with the valve seat in the cylinder head, provided the latter is in goodcondition, will show a contact area of 50 to 100 % of the width of the seating, starting from theoutside diameter (see A�3.1 / 1, Fig. C).

The inlet valve seating surface normally shows no signs of pitting or corrosion marks. However,it tends to become concave due to wear. Such valves do not have to be reground but they have tobe matched with the same valve seat in the cylinder head as before (see A�3.1 / 1, Fig. D).

2 / 5Service Bulletin A-3.1

2. RE-MACHINING OF INLET AND EXHAUST VALVE SEATS IN THE CYLINDERHEAD

2.1. General

20

16

12

8

6

4

0

”Chris-Marine” - type ”Hunger” - type

Valve Seat Grinding Machine

The centring of the device in the valve guide must be absolutely correct.

To prevent chatter marks, the cylinder head must be placed on thick rubber matting, especiallyonboard ships, in order to exclude any vibrations from running machinery.

The handling and operation of the grinding tool is described in the manual supplied with thegrinding machine and should be carefully observed.

After machining, the ground surface must be as smooth as possible.

Valve seating angle = 30° + 2’

0

3 / 5 Service Bulletin A-3.1

2.2. Reconditioning is necessary- Whenever new valve seats have been fitted into the cylinder head.

- When new or reconditioned valves are to be fitted.

- When the seating surface, especially on the exhaust valves of engines operating with heavyfuel oil, shows pitting and corrosive marks, etc.

2.3. Reconditioning is not necessary- When the valve seats are neither worn nor damaged.

- When the surface of the seat of an inlet valve is only slightly convex and the same valve asbefore is fitted again to this valve seat.

2.4. Cleaning after remachiningNo chips, cuttings or grinding dust may remain in the cylinder head. A thorough cleaning andchecking has to be carried out after completing the work.

2.5. Checking of the valve seatingAfter reconditioning, it is essential to check the correct contact of valve and seat.

Using marking blue, the contact area between valve and seat has to be 50�100 %, starting fromthe outside diameter (see A�3.1 / 2, Fig. A).

Remachining of the valve seat is only permissible to a maximum depth of 1 mm. (Please refer toenclosure A�3.1 / 2).

2.6. Touch up after the remachiningAfter the seat has been remachined the top diameter has to be corrected to the original value asshown in Fig. B, C and D on enclosure A�3.1 / 2.

This correction is necessary so that the valve, even after a longer operating time, cannot jam ornot be seated fully, due to some protrusions.

The remachining of the valve seat is only permissible to a maximum depth of 1 mm (please referto enclosure A�3.1 / 2).

The maximum outside diameter, thus obtained, can be taken from the table below:

Engine Type Exhaust ValveDia.”A” (new)

Exhaust ValveDia.”B” (recond.)

Inlet ValveDia.”C” (new)

Inlet Valve Dia.”D” (recond.)

A 20 D (MDO) 63.7 mm 65.7 mm 63 mm 65 mm

A 20 H (HFO) 63 mm 65 mm 63 mm 65 mm

A 25 97.5 mm 99 mm 97.5 mm 99 mm

AS 25 D (MDO) 82.5 mm 84 mm 82.5 mm 84 mm

AS 25 H (HFO)AT 25 D (MDO)AT 25 H (HFO)

82 mm 84 mm 82 mm 84 mm

4 / 5Service Bulletin A-3.1

Good experience has been gained with valve grinding machine tools from the following twocompanies:

Chris Marine AB L.Hunger Stenyxegatan 3 Grafelfingerstrasse 146S�21376 Malmö / Sweden D�81375 Munich / Germany

The above�mentioned machine tools can be ordered from New Sulzer Diesel After SalesService or through any of their Representatives.

3. TURNING OF VALVE SEATS ON MDO-ENGINES

Grinding is foreseen for HFO installations, but itcan be applied on MDO engines too. For valveseats on MDO installations a turning deviceinstead of a grinding machine is supplied. Pleaserefer to the list below.

Engine Type Turning Grinding

A 20 D yes (yes)*

A 20 H no yes

A 25 D yes (yes)*

AS 25 D yes (yes)*

AS 25 H no yes

AT 25 D/H no yes

* grinding tool is not standard supply!

+ 2' 030�

5 / 5 Service Bulletin A-3.1

4. SERVICE BULLETINS VALID FOR A -TYPE ENGINES

We have so far published the following Service Bulletins which are valid for A type engines:

A-2.2 dated 30.11.94 / Assessment of Main and Bottom End Bearings

A-4.1 dated 01.06.95 / Lubricating Oil Treatment

A-5 dated 11.07.85 / Flushing Instructions

A-6 dated 30.10.86 / Undersized Bearings and Reconditioning of Crankshafts

A-7.1 dated 30.11.93 / Fuel Injection Nozzle Specification

A-8 dated 15.08.94 / Cylinder Liner with a Fine Thread in the Upper Part of the Bore

A-9 dated 18.10.94 / Heavy Fuel Oil Concept Guide and System Adjustments forA 20H / AT 25H Auxiliary Engines

A-10 dated 25.07.95 / New Plunger and Barrel for Fuel Pump of AT 25 Engines

A-11 dated 15.09.95 / New Piston Ring Fitting Tool

A-12 dated 15.09.95 / Modification to the Governor Drive ofPG 12 and UG 8 Woodward Governors

Should you not be in possession of the above mentioned documentation suitable for your plant,kindly contact your local New Sulzer Diesel representative for your copy.

ENCLOSURES: as mentioned in the text

New Sulzer Diesel Switzerland Ltd has issued this Service Bulletin with their best knowledge andability. However, New Sulzer Diesel Switzerland Ltd can not take any liability for any or allinformation contained in this or any other Service Bulletin.

Changes of any nature to the form and or to the content of this or any other Service Bulletin aspublished by New Sulzer Diesel Switzerland Ltd, are not permitted.

Service Bulletin Enclosure A–3.1/1

Straight edge

Wear

Valve head

ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ

ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ

F

0-2'30°

50 - 100%

Contact surface

min

. 5

a

A

B

D

C

Grinding of Valve Spindle Seats

ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ

min

. 4

Ø 83 Ø 98

Service Bulletin Enclosure A–3.1/2

ÛÛÛÛ

ÛÛÛÛÛÛÛÛ

ÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜ

A

B

DÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜ

C

ÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜ

0.5

max. 1.0

ÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜ

0.5

max. 1.0

0.5

max. 1.0

Grinding of Valve Seats

� AT 25 HFO & MDO, AS 25 HFO Inlet and Exhaust Valve Seat� A 20 HFO Exhaust Valve Seat

� AS 25 MDO, A 20 HFO & MDO Inlet Valve Seat

� AS 25 MDO, A 20 MDO Exhaust Valve Seat� A 25 Inlet and Exhaust Valve Seat

50 - 100 %

Ø B or D

Ø A or C

Ø B or D

Ø A or C

Ø D

Ø C