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Publ. No. 3061
Marine diesel engine
This workshop manual contains repair instructions for the MD5A marine diesel engine. The instructions
concerning overhauling describe the most suitable working method to be used with the special tools listed under
the heading "Special tools".
Both the engine designation and its serial number must be clearly stated in all correspondence concerning the
engine and when ordering spare parts. We reserve the right to carry out design modifications and, for this
reason, the contents of this manual cannot he regarded as binding.
AB VOLVO PENTA
Technical Information Department
NEW UNITS OF MEASUREMENT
Technicians have long since tried to establish an internationally standardized system of
measurements. In 1960 a decision was made to use a system called SI (Systéme International
d'Unites). To a large extent, this system is based on earlier systems but the units have been
made uniform so that no conversions are necessary.
The SI-system is now being applied within industry in Europe, This manual contains the new SI-
units. The units used previously however, are also stated but in brackets.
The new units are:
Output is slated in kW (kilowatts)
earlier unit h.p. (horsepower)
Torque is stated in NM (Newton-metres)
earlier unit kpm (kilopond-metres)
Engine speed is stated in r/s (revolutions per second)
earlier unit r.p.m. (revolutions per minute)
Displacement and volumes are stated in dm cubic decimetres)
earlier unit l (litres)
Pressure is stated in Pa (Pascal)
earlier unit kp/cm (kiloponds per square centimetre).
Reproduction permitted if source quoted
Electrical system, thermostat housing cylinder head 3
Flywheel, fuel injector pump 4
Oil pump, transmission cover, governor 5
Lubricating oil pump, camshaft, cylinder 6
Crankshaft, cylinder liner, camshaft bearing 7
Lubricating oil pump, sea-water pump 79
Feed pump 9 11
Fuel filter, crankshaft 11
Centrifugal governor, piston 12 13
Valve guides, nozzle sleeve 14 15
Valves, valve seats, rocker mechanism, injector 15 16
Hand start mechanism, camshaft 17
Cylinder liner, crankshaft 18
Cylinder, camshaft, governor 19
Lubricating oil pump, transmission cover 20
Adjustment of control rod travel, assembling
flywheel cover 20 21
Oil sump, cylinder head, feed cover 22
Fuel filter, injector, thermostat 22
Flywheel, generator, valve adjustment 24
Checking injection angle 25
Bleeding the fuel system, electrical system 26
Wiring diagram 27
Fault-tracing system 28
Special tools 29
Technical data 30 33
1. Connection for hand start
2. Fuse box
3. Thermostat housing
4. Decompression lever
6. Oil filler Cap, engine
7. Water drain tap, gearbox
8. Oil drain plug, gearbox
9. Water drain tap, engine
10. Oil filler, gearbox
11. Sea-water pump
12. Dipstick, gearbox
13. Fuel filter
14. Bleed screw
15. Hand pump, fuel
16. Dipstick, engine
17. Oil filter
1. Drain the cooling water and the oil from the engine. Clean 3. Remove the rocker cover and the fuel pipe between the
externally afterwards. Loosen the water hose between the pump and the injector and unscrew the rocker gear. Note!
gearbox and the sea -water pump and remove the gearbox. Pull the rocker gear straight up since it is centred with a
guide pin 1. The other hole 2 is an oil channel.
2. Remove the generator and its drive belt, starter motor, 4. Remove the push-rods 1, remove the cylinder head and
fuel filter and fuel pump with the drain-off pipe (be careful of the cylinder head gasket. Take care of the washers 2 under
fuel spillage), coolant water pump with hose and thermostat the nuts.
housing, dipstick, temperature and oil pressure sensors.
Unscrew and discard the oil filter.
5. Remove the flywheel nuts. Spanner jaw width 55 mm 7. Remove the cover for the injection pump. Note! The
(2 5/32"). Use a wooden shaft or something similar as a bracket for the cold start is fixed with one of the screws.
counter force in the flywheel spokes. Take care of the spring under the cover.
6. Fit tool 884078 to the flywheel. Afterwards screw in the 8. Prise the lower ball joint free from the pump with a
centre screw on the tool until the flywheel loosens. screwdriver.
9. Remove the pump screws. Position the ball in the centre 11. Remove the governor by loosening the hexagonal set
and remove the pump. screw (1), the governor and the gear wheel can then be
10. Remove the sump and then the transmission cover (13 12. Remove the screw and the locking washer for the
screws). The lifting eye is fixed one of the screws. The cover gearbox drive flange on the crankshaft and remove the
is centralised by guide pins. flange with a puller. (Use counter force.) Remove the key
13. Remove the lubricating oil pump. Discard the gasket. 15. Remove the gearwheel on the camshaft's flywheel side
(4 screws). Then remove the camshaft and the gearwheel.
14. Remove the cover (flywheel side), 10 screws. The cover
is centred with guide pins. The screws by the guide pins are 16. Mark and remove the bearing cap on the crankshaft and
fitted with thick washers. carefully knock out the piston through the cylinder.
17. Remove the main bearing caps. Take care of the axial 19. Bearing replacement. Press out the camshaft bearings if
thrust bearings 1 on the transmission side. Lift the crankshaft they are damaged or if the wear is too great (see technical
out and the bearing shells afterwards and then the axial data). Clean the bearing housings and ensure that the oil
bearing halves. channels are clean. Press in the new bearings so that the oil
holes face the corresponding oil channels in the block. When
the bearings are pressed in position they are to be reamed
(see technical data).
20. Remove the gearwheel's nuts and pull off the gearwheel
18. Mark the cylinder liner's position in the cylinder so that with a puller. The gearwheel sits on a key, take care of this
the same position can be obtained during assembly. key.
Remove the cylinder liner. Use tool 884551. Use the long
screw and its nut from the tool 884231 (MD21-MD32). See
page 29 Special tools. Discard the 0-ring. Afterwards remove
the 0-rings in the block which provide a seal for the cylinder
liner and then remove the valve lifters. Wash all the parts
and replace those damaged.
21. Remove the steel wire which holds the filter. Remove Overhauling the sea-water pump
and clean the wire gauze thoroughly. Afterwards remove the 23. The sea-water pump is a round flange type pump which
six screws which hold the cover in position. Discard the means that it can be fitted in a position best suited to the
gasket. coolant water hoses. The new pump is fitted with an 0-ring
which forms a seal against the engine.
22. Remove the gearwheel from the housing. Remove the 24. Remove the cover (6 screws). Change the impeller with
split pin for the reduction valve. Remove washer 1, spring 2 the help of two screwdrivers or something similar. Note!
and piston 3. Clean and replace damaged parts. Assemble Protect the edges of the pump housing. See the figure. Prise
the lubricating oil pump in the reverse order. Note! Fit a new out the impeller with the screwdrivers so far that the screw
gasket 4 between the housing and the cover. Fix the wire becomes visible.
mesh 5 in position with the steel wire 6 and finally lay the key
in position and tighten the gearwheel 7.
25. Unscrew the screw and withdraw the impeller from the 27. Fit new sealing rings. Note! The sealing rings must face
shaft. If the sealing rings are to be replaced, the shaft and the right way, see that they do not block the drain hole in the
the impeller can be removed and the screw subsequently pump housing. Smear grease on the shaft and fit it carefully
loosened. in the housing. Screw it through the sealing rings so that
they will not be damaged. Place the shaft so far into the
housing that the hole for the screw is visible. Fit the impeller
and screw in the screw. Then carefully press in the impeller
so that it touches bottom. Place a new gasket on the cover
and tighten the cover with the six screws.
26. Remove the sealing rings 1 and the 0-ring 2 (earlier Overhauling the feed pump
engines) and clean the housing and the shaft. (Note! The 28. Depress the pump's lever (see fig.). If the pump "creaks"
pump must be removed from the engine.) Check that there then it is sound. If it is unserviceable the diaphragm must be
are no abrasions on the shaft. Note! A new 0-ring is not to be replaced which is done in the following manner:
29. Remove the cover's centre screw, remove the filter 1 31. Depress the diaphragm and shake the pump arm
and clean it. spindle out until the pump arm is free. Then remove the
diaphragm from the housing.
30. Remove the six screws which hold the upper and lower 32. Remove screw 1 and withdraw the manual pump arm 2
pump halves together. Remove the pump's spring and undo and replace spring 3 if it is broken. Note! Be careful of the
screw 2 which holds the pump arm spindle. rubber seal which is pressed into the housing.
33. Clean the pump housing carefully and replace worn Crankshaft
parts. Refit the manual pump arm. Press in the diaphragm 35. Remove the circlip with circlip pliers. Then remove the
and connect the pump arm to the diaphragm centre pin. gear drive. Use a press or a gear puller. Clean the
Then push the spindle in and tighten it with the screw. Note! crankshaft and carry out control measurements of all the
Do not forget the washer under the screw. bearing surfaces. Grind the shaft where necessary. See
Lay the gauze filter on the upper housing and screw the technical data.
cover and the gasket tight. Press in the pump arm 3,
assemble the two housing halves and fit the spring retainer 2
on the mechanical pump arm 3. Note that the spring retainer
can only be fitted one way. Replace the spring next and the
0-ring 4 which provides a seal for the engine.
34. When the filter insert is changed the centre screw 1 is 36. Place the key in the crankshaft's key slot. Heat the
removed allowing the filter holder to be removed. Afterwards gearwheel to approximately 1000C (2120F) (no more) and
remove the filter insert by lifting the plastic loop 4. Wash the press it onto the crankshaft. Note! The marking on the
filter holder clean and fit a new filter. Fit a new packing gearwheel shall face outwards. Refit the circlip on the
washer 5 and refit the holder to the cover with the centre crankshaft.
37. Clean the governor. Check to see if the weights 2 grip 39. Mark the piston and the connecting rod. Remove the
on their spindle or if there is too much movement between circlips. Press out the gudgeon pin with a drift. (The piston
the spindle and the governor weight. Afterwards check that can be heated first to ease removal.)
the pin 1 slides easily in the spindle. Finally check both the
ball bearings 3. Replace the ball bearings if they are tight.
Check that all the movable parts move easily, lubricate and
refit them in the reverse order.
38. Remove the piston rings with the help of piston ring 40. Press the bush out of the connecting rod if it is worn or
pliers. Clean the piston and be particularly careful about the damaged. Then knock out the connecting rod screws. Note!
piston ring grooves. The screws must always be changed when the connecting
rod has been dismantled.
41. Knock new screws in place and press a new bush in the 43. Fit the piston rings with the help of piston ring pliers.
connecting rod. Ensure that the lubricating hole 1 in the bush Start with the oil scraper ring in the lowest groove. The oil
aligns with the hole in the connecting rod. Ream or diamond scraper ring can be fitted either way. Continue with the
drill the bush to an accurate free fit. Check that the gudgeon compression ring which is marked "TOP" on one side. This
pin slides through the bush due to its own weight. (See also marking shall face upwards when fitted. The piston ring with
the technical data.) Fit one of the circlips and oil the gudgeon the chromium insert is fitted last and can be fitted either way.
pin and connecting rod bush. Heat the piston to
approximately 700C (1580F) and assemble the piston and
the connecting rod according to the marking. Note! The
gudgeon pin must be able to be pressed in easily. Fit the
42. Control the dimensions of the piston with a micrometer. 44. Remove the collets, the collars and the valve springs
Measure at right angles to the gudgeon pin holes at the with the help of a valve spring compressor. Remove the
piston's lower edge. Afterwards check the new rings' play in valves. Remove the valve seal from the inlet valve. Burnt
the piston ring grooves. (See technical data.) valves are discarded if worn too much and damaged seats
are to ne machined when necessary. (See technical data.)
The valves and valve seats are to be ground together so that
the mating surfaces provide a complete seal.
Replacing valve guides Nozzle sleeve
45. The valve guides must be replaced if there is too much 47. Remove the injector sleeve with tool 884541. Insert the
play between the valve stem and the valve guide. (See expanding screw in the nozzle sleeve and screw anti-clock-
technical data.) Press out the valve guides with tool 884538. wise until the screw has expanded and gripped the sleeve.
Tighten hard so that the threads bite into the copper. Fit the
yoke onto the studs which hold the nozzle. Screw on the nut
and tighten until the sleeve is removed.
46. New valve guides are fitted with tool 884549. Use a 48. Remove the 0-ring which provides a seal between the
press. This tool gives the guide the right height above the sleeve and the cylinder head. Clean carefully and dry with
cylinder head's valve spring seat surface. Check the dimen- compressed air and then dip the new 0-ring in a soap
sion "A" - this must be 9 mm (0,3543 in.) when the guide is solution to facilitate assembly. Lubricate and fit the new
pressed into place. nozzle sleeve with tool 884557. Knock in the sleeve until it
49. Lubricate the mandrel tool 884537 and insert the tool Valve and valve seat grinding
into the sleeve. (Ensure that the centre screw is sufficiently 51. Machine the valve seats by milling or grinding them.
unscrewed.) Place some nuts or several washers on the Grind no more than is necessary to give the seat the correct
studs so that the yoke can be tightened in place with the shape and a good mating surface. The seat angle C shall be
fixing nuts. Screw in the mandrel as far as the mating face of 45° and the width "B" approximately 1 mm (0,0394 in.). The
the sleeve allows. The mandrel is then withdrawn. Remove width is adjusted with a 39° and a 60° miller respectively or
the tool. a grinding disc. Clean the valves and grind them in a
machine. The valves' face angle D shall be 44,5°. The
sealing surface is ground no more than is necessary to
"clean" it. If less than 1 mm (0,0394 in.) is left on the valve
edge it is to be discarded. Likewise the valve is discarded if
the valve stern is not straight or if dimension "A" exceeds 2,5
mm (0,0984 in.). Note! If this dimension is exceeded even if
a new valve is fitted, the cylinder head must be changed.
50. Adjust the length of sleeve protruding from the cylinder
head face, (length is 0,9 mm) (0,0354 in.) and check that the
sleeve is correctly fitted (dimension 19,5 mm). (0,7677 in.).
52. Remove the circlip from the rocker shaft and remove the
rocker arms. Clean the parts. Be particularly careful when
cleaning the rocker shaft oil channels 3 and the rocker arm's
oil hole, see also fig. 53.
53. Check the wear on the rocker shaft. Also check that the Pressure testing the nozzles
tappet adjustment screw's spherical part is neither deformed 55. Check the shape of the jets at an opening pressure of
nor worn. The threads on the screw and the locknut must be 185 kp/cm 2 (2631 p.s.i.). Also check that the fuel spray
undamaged. discontinues simultaneously at all four holes and that no
Oval rocker arm bushes are to be replaced. Pressing in and subsequent drops appear.
out is performed with drift 884560. Press the bush in so that
the oil hole assumes the position shown in the figure. The
bush is reamed to a light push fit after it has been pressed
in. Lubricate the shaft and assemble the rocker mechanism.
54. Fit the rubber seal 1 on the inlet valve. Use tool 884497. Adjustment of opening pressure
Oil the valve sterns before they are inserted in their 56. The opening pressure is adjusted with adjustment
respective valve guides. Afterwards fit the valve springs, washer 1, which is available in thicknesses between 1 mm
collars and collets with the help of a valve compressor. (0.0394 in.l and 1,95 mm (0.0768 in.) with a difference of
0,05 (0,0020 in) mm between each size. Dismantle the
nozzle and replace the washer with a thinner or thicker
washer depending on whether the pressure is to be reduced
or increased. Assemble the nozzle and check the opening
pressure and jet shape. Continue until a satisfactory result is
Flywheel cover and hand starting mechanism that the transmission cover must be machined since the
57. Unscrew nut 1 and remove it and washer 2 holding the new camshaft gear is thicker than the earlier gear and
hand starting gearwheel 3. Then remove the gearwheel from consequently there is not enough space for it in the
the shaft A. Knock the shaft out from the cover. Loosen the transmission cover. The axial guide face distance A must be
set screw 5 which holds the spacer washer and knock out the filed down by 3mm (0,1181 in.).
spacer washer when the bearings 7 has been removed.
Remove key 8, slide off the spacer ring 9 and pull off ball
bearing 10 after which seal 11 can be pulled off. Note! If only
the seal 11 is to be changed, pin 12 can be knocked out, after
which the seal can be removed.
If the camshaft is damaged this means that the camshaft
gear must be replaced in this case as well. This also means
that the axial guide face must be filed down by 3 mm
58. Replace damaged parts and reassemble the pin, seal,
ball bearing and spacer ring on the shaft. Fit the spacer
washer into the cover and tighten it in position with the set
screw. Note! Ensure that the spacer washer's groove faces
the locking screw's centre. Fit the shaft in the cover. Place the
key in position and then the ball bearing. Fit the gearwheel.
Secure it with a washer and nut. Knock out seal 1 from the
flywheel cover. Press in a new seal afterwards.
60. If the transmission cover is damaged and must be
replaced, this means that even the camshaft and the
camshaft gear must be replaced. The replacement is
necessary because the axial guide in the new transmission
cover is shortened by 3 mm (0,1181 in.) which in turn
means that the camshaft will have an axial play of 3 mm
The camshaft, camshaft gear and transmission cover are
interchangable as of engine no. 1076 inclusive. When
changing camshaft gears of a later type, the camshaft shall
be pressed out of the camshaft gear.
Take care of the key. Check the camshaft for wear. See the
Place the key in the camshaft and press on the camshaft
gear. The distance from the camshaft end to the camshaft
gear's hub must be 136 mm (5,354 in.). See fig.
59. In such cases (on engines with engine nos. 100-1075)
where a camshaft gear change is necessary, the camshaft
must be changed as well. A new camshaft gear cannot be
fitted to an early type of camshaft. Furthermore this means
ASSEMBLING 63. Place the main bearing halves with the oil channel holes
61. Check that the liner is not scratched and that it is in in the block. Then place the axial bearing halves in position.
good condition otherwise. Fit new 0-rings 1 in the block (2 Turn the oil grooves 1 outwards.
off) and a new 0-ring 2 on the cylinder liner. Turn the mark
on the liner (which was made during dismantling) to the mark
on the block. Lubricate the 0-rings and fit the liner. Be careful
not to damage the 0-rings.
62. When the cylinder liner is fitted in the block the height of 64. Oil both the bearing halves and place the crankshaft in
the liner outside the block must be measured. The height position. Fit the main bearing shells in the bearing housings
must not exceed 0,05 mm (0,0020 in.) and must not be less and place the axial bearings with the oil grooves outwards.
than 0,01 mm (0,0004 in.), otherwise there is a risk that a Fit the bearing housing so that the indentation in the housing
leak can occur. faces the same way as the indentation in the bearing half
already in the block. Tighten the bearing housing with a
torque of 70 Nm (7 kpm) (50 Lbft.).
65. Remove any wear edges in the cylinder liner. Oil the 67. Fit the camshaft with the camshaft gear. Align the marks
cylinder liner and fit the piston in the block. Use a piston ring on the crankshaft gear and the camshaft gear.
sleeve or tool 9992176. Turn the piston so that the machined
depression in the piston crown faces the nozzle side.
66. Oil and fit the big end bearing shells in the bearing half.
68. Fit the governor. Tighten it in position with the set screw
Turn mark to the correct position and fit the bearing half.
Tightening torque: 70 Nm (7 kpm) (50Lbft.). on the side. See that it goes into the groove.
69. Fit the gearwheel on the camshaft's opposite end. 71. Fit a new gasket for the transmission cover. Afterwards
fit the transmission cover. Fix the lifting eye with the upper
Adjustment of control rod travel
72. Fit a new gasket and fit the injector pump. Press on the
ball end of the control arm. Measure and check that the
control rod travel is correctly adjusted. (The same as prior to
dismantling.) The measurement must be carried out with a
new gasket. Set the control at full throttle. Press down the
plunger to bottom position. Note that the cold start must not
be engaged during measurement. The exact amount
injected can only be determined when checking in a test
70. Fit the oil pump. Note the different screw lengths.
73. Release the plunger 8 mm (0,3150 in.) and measure the 75. If the engine smokes abnormally, the centre screw on
distance from the transmission cover face to the adjusting the cover can be loosened and the adjusting screw can be
screw's contact point on the control arm. adjusted until the engine runs smoke free. See the technical
data for the correct injection amount.
74. Measure the adjusting screw's length and adjust any 76. Fit a new gasket and fit the flywheel cover. Be careful so
eventual deviation so that the plunger stops when released 8 that the sealing ring is not damaged. Trim the excessive
mm. Screw down the cover afterwards. gasket.
77. Fit a p lane packing and then fit the sump. Note! On 79. Replace the tappet rods and fit the rocker mechanism.
earlier engines a rubber seal was used. This is to be Check that the guide pin in the cylinder head goes into the
replaced by a plane packing. hole in the rocker mechanism.
80. Lubricate the oil filter rubber seal. Screw in the oil filter
78. Lubricate and replace the valve lifters. Fit a new cylinder so far that the rubber seal first contacts the engine body.
head gasket and then the cylinder head. Place the washers Afterwards screw in the filter a further half turn. Note!
under the nuts and tighten the nuts in three stages to 70 Nm Tighten by hand. Then fit the feeder pump. Use a new 0-ring
between the pump and the engine.
(7 kpm) (50Lbft.). See the tightening sequence.
First stage: 10 Nm (1 kpm) (7Lbft.).
Second stage: 40 Nm (4 kpm) (29Lbft.).
Third stage: 70 Nm (7 kpm) (50Lbft.).
81. Fit the fuel filter. Place sealing rings on both sides of the 83. Connect the injector pipe, the temperature and oil
fuel pipe unions. pressure transmitters.
82. Fit the injector. The tightening torque = 10 Nm (1 kpm) 84. Lower the thermostat into hot water and check with a
(7Lbft.). Then connect the fuel drain pipe. Note! Place thermometer if the thermostat opens and closes correctly at
sealing rings on both sides of the pipe unions. the right temperature. It should start to open at 600C 140 0F
and should be fully open at 900C 194 0F. If the thermostat is
defective it must be replaced. Clean the thermostat and fit a
new gasket 1. Place the thermostat in the engine and fit the
thermostat housing. Then fit the water pump and connect the
coolant water hose.
85. Place the key for the gearbox connecting drive on the 87. Fit the starter motor and the alternator. Note! Place the
crankshaft on the gearbox side. Heat the connecting drive spacer tube correctly and assemble the belt tensioner. Fit
and fit it onto the crankshaft. Lock the drive with the large and tension the drive belt so that it can be depressed 3--4
washer and the lockwasher. Tighten the screw with a torque mm (0,1181--0,1575 in) with normal thumb pressure.
wrench. The tightening torque is 70 Nm (7 kpm) (50Lbft.).
Use a counter force. Bend the lockwasher up against the
screw head afterwards.
88. Turn the flywheel until both tappets function. Turn the
86. Place the key for the flywheel in the crankshaft's key flywheel a further complete turn and adjust the tappets. The
slot. Fit and tighten the flywheel. Use a counter force in the clearance is 0,30 mm (0,0118 in.) for the inlet valve (nearest
flywheel) and 0,35 mm 10,0138 in.) for the exhaust valve
spokes of the flywheel. The tightening torque is 500 Nm (50
when the engine is hot. Fit the rocker box cover and a new
kpm) (362Lbft.). Spanner jaw width is 55 mm (2 5/32").
INJECTION ANGLE CONTROL 91. Open the level valve 1 on the measuring apparatus so
89. A Wilbär tube is used when checking the injection angle. that the level lies 25 - 30 mm (1" - 2 3/16") from the bottom.
Fit the Wilbär tube on the pressure pipe nipple. Turn the engine in the rotation direction until compression is
90. Rotate the engine in the correct direction until the level 92. If the injection angle does not meet the prescribed
tube 1 is full with air-free fuel. value, the number of washers 1 between the pump housing
and the transmission cover is increased or decreased until
the correct value is obtained. One washer gives a difference
in injection angle of approximately 1°.
93. Fit the exhaust elbow and the gearbox. Use new
gaskets. Check that the rubber damper is not damaged. ELECTRICAL SYSTEM
The following applies to engines fitted with alternators:
1. Do not break the electrical circuit between the
alternator and the battery when the engine is running.
If a main switch is fitted it must therefore not be
turned off until the engine is stopped.
No lead must be disconnected when the engine is
running since this can irreparably damage the charging
2. The battery, battery cable and cable terminals are to be
checked regularly. The battery poles are to be properly
clean and the cable terminals are to be tight and well
greased so that a break in the circuit cannot occur. All
other cables are to be properly connected, no loose
connections must occur. The battery's positive and
negative connections must on no condition be exchanged
when the battery is connected.
3. When starting with an auxiliary battery, check first that it
BLEEDING THE FUEL SYSTEM has the same rated voltage as the standard battery.
94. Fuel system bleeding is always carried out in the Connect the auxiliary battery with positive to positive and
following cases: When the microfilter is changed - when negative to negative. Remove the auxiliary battery when
draining via the drain plug - when cleaning the gauze in the the engine has started. Notel The cables to the standard
fuel pump - when the fuel tank has run dry - when fitting an battery must on no condition be disconnected.
injector pump - after leaks in or repairs on, the fuel piping -
when the engine has been out of use for a long time. 4. When carrying out electrical welding on the engine or
Bleeding is carried out as follows: associated installation parts the charging regulator's
Open the air bleed screw 1 in the microfilter. Pump up fuel cable must be disconnected and insulated first. After-
using the hand pump 2 until clean air-free fuel runs out. wards both the battery cable terminals can be removed.
Close the air bleed screw. If the pump effect is poor rotate 5. When carrying out repairs on the generator, both battery
the engine until the pump's drive cam assumes another cable terminals must always be disconnected. The same
position. If the injector pump has been dismantled or, when applies if the battery is given a quick charge.
the engine is to be started for the first time after renovation,
the injection pump must be bled. Open the air bleed screw 3 6. Never test a connection with a screwdriver or similar tool
on the injection pump. Pump the hand pump 2 until air-free to see if it sparks.
fuel runs out. Loosen the pressure connection 4 and rotate
the engine with the starter motor until fuel runs out from the
pressure pipe. Tighten the pressure connection and start the
Designation Colour mm2 A.W.G. Circuit explanation
A White 6 9 1. Extra switch
B Black 1.5 15 2. Charging control lamp
B' Black 0.6 19 3. Temperature warning lamp
B" Black 0.75 18 4. Oil pressure warning lamp
C Red 6 9 5. Key switch
C' Red 35 1 6. Warning unit
C" Red 0.6 19 7. Screw
F Yellow 1.5 15 8. Charging control lamp (for secondary battery
G Brown 1.5 15 circuit, extra equipment)
H' Blue 35 1 9. Place for instruments, extra equipment.
I Green/Red 1.5 15 10. Snap connection
I' Green/Red 0.75 18 11. Starter motor
J Green 1.5 15 12. Alternator
J' Green 0.6 19 13. Fusebox
J" Green 0.75 18 14. Main switch
K Blue/Yellow 0.75 18 15. Battery
L White/Red 0.75 18 16. Temperature sender
M Blue/Red 0.75 18 17. Oil pressure sender
The fault finding chart given below only covers the most common faults which occur.
The engine does not reach
The engine runs rough or
the correct speed at full
The engine becomes
Engine will not start
X Main switch not connected, flat battery, cable See para A
X X Empty fuel tank, fuel tap closed, blocked fuel See para B
X X X Water, air or impurities in the fuel. See para B
X X X X Faulty injector. See para C
X Boat abnormally loaded, boat bilge fouled with See para C
X X Propeller damaged. See para E
X Clogged coolant water intake, cooling vanes, See para F
defective pump wheel or thermostat.
A. Check the charge state of the battery with the help of a
hydrometer which shows the specific gravity of the D. To obtain the best operational economy, the engine
battery acid. This varies according to the state of the speed should be at least 300 r.p.m. less that the
charge, (see the technical data). (See furthermore maximum obtainable during extended running periods.
"Electrical system" p. 26.) Note! If the boat has been in the water a considerable
time, the maximum obtainable engine speed can
B. Change the microfilter by unscrewing the hexagonal decrease due to growth on the hull's underside. Use
head on the filter holder's base. The microfilter and its growth inhibiting bottom paint.
holder are of a discardable type which means that the old Check and clean the hull regularly.
filter is discarded and a new one fitted. Check that the
face of the cover is completely clean and that the filter E. Check that the propeller blades are whole. If any of the
packing is undamaged. Screw the new filter by hand until propeller blades are damaged, the propeller should be
the packing contacts the cover. Then tighten the filter a changed. A propeller blade can be out of line (twisted) --
further half turn. There is a drain plug in the bottom of the this is very difficult to detect. Place the propeller on a flat
filter holder for draining water and impurities in the fuel. surface and measure the blades. If any blade is twisted
Bleed the fuel system after draining and after a filter the propeller should be changed.
change and then check for tightness.
Remove the cover on the feed pump and clean the pre- F. Check the coolant system from the point of view of
filter in diesel oil. Refit the filter with the notches upward leakage, blockage etc.
and fit an undamaged packing and tighten the cover. Check that the thermostat opens at the correct tempera-
Bleed the fuel system. ture. The thermostat can be taken out when the
Check and drain when necessary the extra fuel filter if thermostat housing has been dismantled. See also
one is fitted. Look out for spilled fuel. paragraph 84.
The pump impeller in the sea water pump is made of
C. Check the injector with reference to opening pressure, neoprene rubber and can be damaged when the water
tightness and jet shape. It is recommended that these supply is cut off, for instance if there is a blockage in the
checks be carried out after a maximum operation time of sea water intake. Paragraphs 23--27 should be followed
400 hours or once per season. See also paragraphs 55 when changing a pump impeller and sealing rings. Note)
and 56. If the boat is in the water the sea cock must be closed
before the sea water is dismantled. Do not forget to open
the cock again.
Special tools for the MD5A
Part No Designation
884538 Drift for pressing out valve guides
884549 Drift for pressing in valve guides
884557 Drift for pressing in injector sleeve.
884541 Tool for removing injector sleeve.
884537 Drift for copper sleeve.
884551 + Tool for removing cylinder liner.
884560 Drift for removing rocker arm bush.
884497 Drift for fitting rubber valve seal.
884543 Nipple fixture
884535 Nipple for compression pressure
Effect (DIN) at 40 r/s (2500 r.p.m.) MD5A
No. of cylinders 5.5 kW (7.5 b.h.p)
Stroke 84 mm (3.31 in.)
Displacement, total 80 mm (3.15 in.)
Compression ratio 0,443dm 3 (27 cu. in.)
Compression pressure at starter motor speed 16,5:1
Direction rotation, viewed from flywheel 20 - 22kp/cm 2 11 (144 - 159 psi)
Idling speed Clockwise
9,2 - 10,8 r/s (550 - 650 r/m)
Cylinder liner, wet replaceable
Cylinder diameter, standard mm (in.)
84,000 - 84,015 (3.3071 - 3.3077)
Overall height mm (in.)
Height from gudgeon pin centre to piston crown mm (in.) 77(3,0315)
Piston clearance mm (in.) 49,0 - 49,05 (1.9291 - 1.9311)
Pistons available as standard mm (in.) 0,081 - 0,114 (0.0032 - 0.0045)
83,901 - 83,919 (3.3032 - 3.3039)
Diameter mm (in.)
Inner diameter of gudgeon pin bush mm (in.) 25,996 - 26,000 (1.0235 - 1.0236)
Clearance between gudgeon pin and bush mm (in.) 25,999 - 26,004 (1.0236 - 1.0237)
0,001 - 0,008 (0.00004 - 0.0003)
Number of compression rings
Number of oil rings 2
The upper compression ring has a chromium insert 1
Axial piston ring clearance
Upper compression ring mm (in.)
Lower compression ring mm (in.) 0,070 - 0,102 (0.0028 - 0.0040)
Oil scraper ring mm (in.) 0,050 - 0,082 (0.0020 - 0.0032)
0,030 - 0,062 (0.0012 - 0.0024)
Piston ring gap in cylinder
Upper compression ring mm (in.)
Lower compression ring mm (in.) 0,30 - 0,50 (0.0118 - 0.0197)
Oil scraper ring mm (in.) 0,30 - 0,50 (0.0118 - 0.0197)
0,25 - 0,50 (0.0098 - 0.0197)
Axial clearance (end float) mm (in.)
Main bearings radial clearance mm (in.) 0,05 - 0,30 (0.0020 - 0.0118)
Big end bearing radial clearance mm (in.) 0,040 - 0,096 (0.0016 - 0.0038)
0,040 - 0,096 (0.0016 - 0.0038)
Main bearing journals
Diameter, standard mm (in.)
Diameter, undersized, 0,250 mm (in.) . . 53,987 - 54,000 (2.1255 - 2.1260)
Diameter, undersized, 0,500 mm (in.) . . 53,737 - 53,750 (2.1156 - 2.1161)
53,487 - 53,500 (2.1058 - 2.1063)
Main bearing shells
Thickness, standard mm (in.)
Oversized, 0,250 mm (in.) 1,968 - 1,980 (0.0775 - 0.0780)
Oversized, 0,500 mm (in.) 2,093 - 2,105 (0.0824 - 0.0829)
2,218 - 2,230 (0.0873 - 0.0878)
1) Measured with a Moto Meter, nipple 884535 and fixture 884543.
Connecting rod journals
Diameter, standard mm (in.) 50,987 - 51,000 (2.0074 - 2.0079)
Diameter, undersized, 0,250 mm (in.) 50,737 - 50,750 (1.9975 - 1.9980)
Diameter, undersized, 0,500 mm (in.) 50,487 - 50,500 (1.9877 - 1.9882)
Big end bearing shells
Thickness, standard mm (in.) 1,768 - 1,780 (0.0696 - 0.0701)
Oversized, 0,250 mm (in.) 1,893 - 1,905 (0.0745 - 0.0750)
Oversized, 0,500 mm (in.) 2,018 - 2,030 (0.0794 - 0.0799)
Axial clearance (end float) at crankshaft mm (in.) 0,05 - 0,20 (0.0020 - 0.0079)
Axial clearance (end float) mm (in.) 0,54 - 0,82 (0.0213 - 0.0323)
Radial clearance in bearings mm (in.) 0,025 - 0,075 (0.0010 - 0.0030)
Camshaft diameter mm (in.) 39,975 - 40,000 (1 .5738 - 1 .5748)
Camshaft diameter mm (in.) 46,975 - 47,000 (1.8494 - 1.8504)
Lifting height mm (in.) 5,8 (0,2283)
Bearing diameter mm (in.) 40,025 - 40,050 (1.5758 - 1.5768)
Bearing diameter mm (in.) 47,025 - 47,050 (1.8514 - 1.8524)
Valve disc diameter mm (in.) 34,9 - 35,1 (1.3740 - 1.3819)
Valve stem diameter mm (in.) 7,955 - 7,970 (0.31 32 - 0.31 38)
Valve seat angle 45,5° (see fig. page 15)
Seat angle in cylinder head 45°
Seat width in cylinder. head mm (in.) ca 1 (0.0394)
Tappet clearance, hot mm (in.) 0,30 (0.0118)
Valve disc diameter mm (in.) 27,9 - 28,1 (1.0984 - 1.1063)
Valve stem diameter mm (in.) 7,925 - 7,940 (0.3120 - 0.3126)
Valve seat angle 44,5° (see fig. page 15)
Seat angle in cylinder head 45°
Seat width in cylinder head mm (in.) ca 1 (0.0394)
Tappet clearance, hot mm (in.) 0,35 (0.0 138)
Length, inlet valve mm (in.) 52 (2.0472)
Length, exhaust valve mm (in.) 52 (2.0472)
Inner diameter mm (in.) 8,000 - 8,015 (0.3150 - 0.3156)
Height above cylinder block's spring face mm (in.) 10,65 - 11,35 (0.4193 - 0.4469)
Clearance, valve stem-valve guide: inlet valve mm (in.) 0,030 - 0,060 (0.00 12 - 0.0024)
Clearance, valve stem-valve guide: outlet valve mm (in.) 0,060 - 0,090 (0 .0024 - 0 .0035)
Length unloaded mm (in.) 42,5 (1.6732)
Loaded with a force of 170 N (17 kp) (37,5 lb) mm (in.) 32 (1.2598)
Loaded with a force of 300 N (30 kp) (66 lb) mm (in.) 24 (0.9449)
Engine oil capacity ex. filter (Imp. qts. = US qts.) 2,0 din3 (1.7 = 2.1)
Engine oil capacity inc. filter (Imp. qts. = US qts.) 2,1 din3 (1.8 = 2.2)
Oil quality according to API system CD (DS)
1st alternative. Above + 100C (5Q0 F) Volvo Penta oil
Double grade SAE 20W/30
Below + 100C (500F) Volvo Penta oil Single grade SAE l0W
2nd alternative. Viscosity above + 100Cj500F) SAE 20
Viscosity below + 100 (50~ F) SAE 10
Oil pressure, hot engine, idling kplcm 2 (p.s.i.) 1,5 - 2,5 kplcm 2 (21 - 36)
Oil pressure, hot engine, full throttle kplcm 2 (p.s.i.) 4,0 - 5,0 kplcm 2 (57 - 71)
Lubrication oil filter
Designation MANN W 77 or FRAM PH3614
Lubrication oil pump
Type Gear pump
Spring for pressure reduction valve: Length unloaded
mm (in.) 40 (1.5748)
Loaded with 25 N (2,5 kp) (5,5 lb) mm (in). . 34 (1.3386)
Loaded with 35 N (3,5 kp) (7,7 lb) mm (in.) . 31,5 (1.2402)
Gear's axial clearance including packing mm (in.) 0,010 - 0,130 (0.0004--0.0051)
Injector pump, Bosch PFR 1K 70A 431/11
Injector, Bosch, holder KBAL 65
Nozzle DLLA 150
Hole diameter mm (in.) Four, 0,23 (0.0091)
Opening pressure (new nozzle) kp/cm 2 (p.s.i.) 185 (2631)
Nozzle angle 150°
Pre-injection angle 25 - 28°
Fuel quantity injected 31 min3/stroke at 33,3 r/s (2000 r.p.m)
Type Bosch 0 450 015 003
Filter element Bosch 1 457 431 324
Type Pierburg PE 15672
Feed pressure at 42 r/s (2500 r.p.in) kp/cm 2 (p.s.i) 0,65 - 0,85 (9.2 - 12.1)
Battery voltage 12 V
Battery capacity Max. 60 Ah
Alternator rating, max 35 A
Starter motor rating 0,81 kW (1.1 hp)
Battery electrolyte spec. gray: Fully charged battery 1,275 - 1,285 g/cm 3
Charging to be carried out at 1,230 g/cm 3
Thermostat Bellows thermostat
Starts to open at0C (0F) 60 (140)
Fully open at 0C (0F) 90 (194)
Replaced when worn (or if the engine has an abnormally
high oil consumption) mm (in.) 0,25 (0.0098)
Main and big end bearings
Permissible ovality mm (in.) 0,06 (0.0024)
Permissible conicity mm (in.) 0,05 (0.0020)
Max. axial clearance (end float) mm (in.) 0,36 (0.0142)
Bearing journals, permissible ovality tom (in.) 0,03 (0.0012)
Max. clearance between camshaft and bearings mm (in.) 0,15 (0.0059)
Max. clearance between valve guide and valve stem mm 0,16 (0.0063)
Valve disc edge mm. thickness mm (in.) 1,0 (0.0394)
Cylinder head nuts* 70 Nm (7 kpm) (50Lbft.)
Cylinder head studs 20 Nm (2 kpm) (14Lbft.)
Screw for a gearbox drive on crankshaft 80 Nm (8 kpm) (58 Lbft.)
Flywheel nut 500 Nm (50 kpm) (362Lbft.)
Big end (connecting rod) bearings 70 Nm (7 kpm) (50Lbft.)
Water pump drive 60 Nm (6 kpm) (43Lbft.)
Main bearings 70 Nm (7 kpm) (50 Lbtt.)
Nuts for injector holder 10 Nm (1 kpm) (7Lbft.)
Tightening torque for cylinder head nuts.
* Note! The tightening must be done in three stages.
First stage: 10 Nm (1 kpm) (7Lbft.)
Second stage: 40 Nm (4 kpm) (29Lbft.)
Final stage: 70 Nm (7 kpm) (50Lbft.)