1997 FIAT PUNTO Chapter 12

2D*10 Engine removal and overhaul procedures
4.44a Disconnecting tho radiator top hose from the thermostat housing
4.45b ... and expansion tank hose
lofi-nand side of the cylinder head, From the top ot the radiator and from the expansion tank (see Illustrations). 46 Disconnect the radiator bottom hose from the elbow on the cylinder head.
4.49e ... and the adjustment lockbolt...
4.44b Disconnecting the heater hose st the engine
4.49a Remove the front bracket bolt...
47 On models with a speedometer cable, disconnect the cable from the transmission. 48 On models with an electronic speedometer, if necessary disconnect the winng connector on the support bracket. The cable may be left
4.49f ... and tie the power steering pump to the bulkhead
. m " • V;
<4
4.45a Disconnecting the heater return hose...
4.49b ... the belt adjustment bolt...
attached if Ihe transmission Is not being detached from the engine. 49 On models fitted with power steering, unbolt the power steering pump from the rear right-hand side of the engine without disconnecting the hydraulic fluid lines then tie it to one side on the bulkhead so that it will not obstruct the removal of the engine. To do (his first remove the front bracket bolt, remove the belt adjustment bolt, remove the rear through-bolt, lift away the cover and remove the adjustment lockbolt (see illustrations). On models with air conditioning, similarly unbolt the air conditioning compressor and position It clear of the engine. Do not disconnect the air conditioning refrigerant pipes/hoses. 50 Disconnect the coolant purge hoses from the top of the radiator and expansion tank (seo illustrations). 51 Disconnect the accelerator cable from the injection pump (see Chapter 4Q.
4.50a Disconnecting the coolant purge hoses from the radiator...

2D*10 Engine removal and overhaul procedures
4.70 Lowering the engine/transmission assembly to Ihe floor
4.79a Withdraw the Intermediate shaft...
Separation 71 Rest Ihe engine and transmission assembly on a firm, flat surface, and use wooden blocks as wedges to keep the unit steady. 72 Note the routing and location of the wiring
4.77 Removing the transmission lower cover
4.79b ... and recover the dust boot
harness on the engine/transmission assembly, Ihen methodically disconnect It. 73 Remove the starter motor (Chapter 5A). Petrol engines 74 Noto the location of the earth loads on the
4.78 Removing the bolts securing the intermediate shaft to the bracket on the rear of the cylinder block
transmission support bracket on the rear of the cylinder block, then unscrew the securing bolts and move the leads to one side. 75 Unscrew the bolts on the transmission and remove the support bracket. 78 Unscrew tho remaining bolts and remove the transmission lower cover. Diesel engines 77 Unscrew the bolts and remove the transmission lower cover (see Illustration). 78 Unscrew the bolts securing the Intermediate shaft to the bracket on Ihe rear of the cylinder block (see illustration). 79 Withdraw the Intermediate shaft through the bracket and recover the dust boot from tho inner end (see illustrations). 80 Unscrew the mounting bolts and remove the rpm sensor from the transmission (see illustrations). Manual transmission models 81 Support the transmission with blocks ol wood. 82 Unscrew the transmission-to-engine bolts. Also unscrew Ihe nut securing the transmission to the rear ot the cylinder block (see illustrations). 83 Lift the transmission complete with driveshafts directly from the roar of Ihe engine, taking care to keep It level so that the transmission input shaft does not hang on the clutch (see illustration), Automatic transmission models 84 Support the transmission with blocks of wood.
4.83 Separating the engine from tho transmission (petrol engine)

2D*10 Engine removal and overhaul procedures
05 Remove the brush holder assembly from the automatic transmission as described in Chapter 7B, Section 4. The brushes bear on the slip rings at the rear of the electro-magnetic clutch housing and they may be damaged when the transmission is removed. 86 Unscrew and remove the transmission-to-engine bolts then carefully draw the transmission away from the engine, resting It securely on wooden blocks. Collect the locating dowels If they are loose enough to be extracted, 87 If the oil pump driveshaft remains engaged with the crankshaft, remove it and reert Into the transmission to protect It from damage.
Connection 86 If the engine and transmission have not been separated, go to paragraph 104. Manual transmission models 89 Smear a little high-melting-point grease
on
the splines of the transmission input shaft. Do not use an excessive amount as there Is the risk of contaminating the clutch friction plate. 90 Carefully offer up the transmission to the engine cylinder block, guiding the input shaft through the clutch friction plate. 91 Refit the transmission-to-engine bolts and
the
single nut. hand^jghtenlng 1hem to secure the transmission in position. Note: Do not hghten them to force the engine and transmission together. Ensure that the beilhousing and cylinder block mating faces will butt together evenly without obstruction, before finally tightening the bolts and nut securely. Automatic transmission models 92 Check that the oil pump driveshaft is correctly engaged with the oil pump in the transmission. 93 Carefully offer up the transmission to Ihe rear of the engine and insert the oil pump driveshaft In the centre of the electro-magnetic clutch housing. Locate the transmission on the locating dowels then Insert the bolts and tighten them securely. 94 Refit the brush holder assembly to the automatic transmission with reference to Chapter 7B, Section 4. Petrol engines 96 Refit the transmission lower cover and tighten the bolts. 96 Locate the support bracket on the lower cover, then insert the bolts hand-tight. Also Insert the bolts securing the bracket lo the rear of Ihe cylinder block. With all the bolts Inserted, tighten them securely. 97 Refit the earth leads and tighten the bolts. Diesel engines 98 Refit the rpm sensor and tighten the bolts. 99 Insert the Intermediate shaft through the bracket then locate the dust boot on it and insert the Inner end in the transmission.
100 Refit and tighten the bolts securing the Intermediate shaft to the bracket on the rear of the cylinder block. 101 Refit the transmission lower cover and tighten the bolts. Ail models 102 Refit the starter motor (see Chapter 5A). 103 Refit the wiring harness to the components on the engine/transmission assembly making sure it is routed correctly.
Refitting 104 Locate the engine/transmission assembly beneath the engine compartment and attach the hoist to the lifting eyes. 105 Carefully lift the assembly up into the engine compartment taking care not to damage the surrounding components. 106 Reconnect the left-hand engine/trans-mission mounting to the body and tighten the bolts. 107 Reconnect Ihe right-hand engine mounting to the body and tighten the bolts. 108 Working beneath the vehicle, refit the rear engine mounting and tighten the bolts. 109 Disconnect the hoist from the engine and transmission lifting eyes and remove the hoist from under the vehicle. 110 The remainder of the refitting procedure is the direct reverse of the removal procedure, noting the following points:
a) Ensure that alf sections of the wiring harness follow their original routing; use new cable-ties to secure the harness In position, keeping it away from sources
of
heat and abrasion. b) On vehicles with manual transmission check and if necessary adjust the gearchenge cable and rod with reference to Chapter 7A. c) On vehicles with automatic transmission use new ro//p/ns fo secure the driveshafts to the transmission output stubs. Also check and if necessary adjust the kickdown end selector cables with reference to Chapter 78. d) Ensure that afi hoses are correctly routed and are secured with the correct hose clips, where applicable. If the hose clips cannot be used again; proprietary worm drive clips should be fitted
In
their place. e) Refill the cooling system as described in Chapter 1A or 18. f) Refill the engine with appropriate grades and quantities of oil (Chapter
1A
or 1B). g) Refit and adjust the auxiliary drivebelt(s) wfth reference fo Chapter 1A or 1B. h) Check and If necessary adjust the accelerator cable with reference to Chapter
AA,
48 or
AC.
i) When the engine is started for the first time, check for
air,
coolant, lubricant and fuel leaks from manifolds, hoses etc. If
the
engine has been overhauled, read
the
notes In Section 13 before attempting to starlit.
5 Engine overhaul • dismantling sequence
1 It is much easier to dismantle and work on the engine if it is mounted on a portable engine stand. These stands can often be hired from a tool hire shop. Before the engine is mounted on a stand, the flywheel should be removed, so that the stand bolts can be tightened Into the end of the cylinder block/crankcase. 2 If a stand Is not available, it Is possible to dismantle the engine with it blocked up on a sturdy workbench, or on the floor, Be very careful not to tip or drop the engine when working without a stand. 3 If you intend to obtain a reconditioned engine, all anclllarles must be removed first, to be transferred to the replacement engine (just as they will If you are doing a complete engine overhaul yourself). These components Include the following:
Petroi engines a) Power steering pump if removed with the engine (Chapter
10).
b) Alternator fmcluding mounting brackets) and starter motor (Chapter
SA).
c) The Ignition system and HT components including ail sensors, HT leads and
spark
plugs (Chapters 1A and
SB).
d) The fuel injection system components (Chapters A A and
AB).
e) All electrical switches, actuators and sensors, and the engine wiring harness (Chapters 4A, AB, SB). f) Inlet and exhaust manifolds (Chapters 4A, AB end
AD).
g) Engine oil dipstick and tube. h) Engine mountings (Chapter
2A).
i) Flywheef/driveptate (Chapter
2A).
j) Clutch components (Chapter
6)
- manual transmission. k) Electro-magnetic clutch components (Chapter 7B) - automatic transmission. I) Cooling system components (Chapter
3).

Diesei engines a) Power steering pump //removed with the engine (Chapter
10).
b) Alternator (Including mounting brackets) and starter motor (Chapter 5A). c) The glow plugfpre-heatlng system components (Chapter
SC).
d) Ait fuel system components, including the fuel injection pump, all sensors and actuators (Chapter
AC).
e) The vacuum pump. f) Ail electrical switches, actuators and sensors, and the engine wiring harness (Chapter 4C and 5C). g) Inlet and exhaust manifolds and, where applicable, the turbocharger (Chapter
AC
and 4D). h) The engine oil level dipstick and its tube. i) Engine mountings (Chapter
2C).

2D*10 Engine removal and overhaul procedures
6.5s Prising out the feed stub of the camshaft lubricating pipe J) Flywheel (Chapter 2C). k) Clutch components (Chapter
6).
I) Cooling system components (Chapter
3).
Note: When removing trie external components from the engine, pay close attention to details that may be helpful or important during refitting. Note the fitted position of gaskets, seals, spacers, pins, washers, bolts, and other small components. 4 If you are obtaining a short engine (the engine cylinder block/crankcase, crankshaft, pistons and connecting rods, all fully assembled), then the cylinder head, sump, oil pump, timing belt (together with its tensloner and covers), coolant pump, thermostat housing, coolant outlet elbows, oil filter housing and where applicable oil cooler will also have to be removed. 5 If you are planning a full overhaul, the engine can be dismantled in the order given below: $) Ftywhaoi/drivoplate.
6.5d When removing the camshaft bearing caps, note the position of the (ong and short locating dowels
bearing/banjo union bolt b) Timing belt, sprockets, and tensioner. c) Inlet and exhaust manifolds. d) Cylinder head. e) Sump. f) Oil pump. g) Pistons and crankshaft.
6 Cylinder head - % dismantling, cleaning, inspection and reassembly ^
Note: Now and reconditioned cylinder heads are available from the manufacturer or engine overhaul specialists. Be aware that some specialist tools are required for the dismantling and inspection procedures, and new com-ponents may not be readily available. It may therefore be mors practical and economical for the home mechanic to purchase a reconditioned head, rather than dismantle, inspect and recondition the original head.
Dismantling Note: On 8-valve petrol engines and diesel engines, the camshaft and cam followers are /oca fed In the cylinder head assembly and the relevant dismantling and reassembly procedures are contained in this Section. On 1$-valve petrol engines, the camshafts and cam followers are /oca fed In a separate housing (cylinder head extension) which is bo/fed fo the top of the cylinder head. All procedures relating to the camshafts and cam followers on 16-valve engines are therefore contained in Chapter 2B. Proceed fo paragraph 15 for cylinder head dismantling
6.8a Unscrew and remove the bolts from the thermostat housing, noting the location of the bracket
6.5c Removing the camshaft lubricating pipe procedures on /6-vafve engines, and ignore any references to camshafts, cam followers and oil seals in the paragraphs that follow. 1 Remove the cylinder head as described in Part A. B or C of this Chapter (as applicable). 2 If not already done, remove the inlet and exhaust manifolds with reference to the relevant Part of Chapter 4. Also remove the spark plugs, glow plugs and injectors as applicable. 3 Remove the camshaft sprocket with reference to Chapter 2A or 2C. Petrol engines 4 Mark the positions of the camshaft bearing caps, numbering them from the timing end. 5 Unbolt and remove the lubrication pipe (prise the oil feed stub out with a screwdriver). Unscrew the remaining bolts and take off the bearing caps (see illustrations). 6 Lift the camshaft carefully from the cylinder head, checking lhat the valve clearance shims and cam followers are not withdrawn by the adhesion of the oil (see Illustration). 7 Remove the shims and cam followers, but keep them In their originally fitted order. Diesel engines 8 Unbolt the thermostat housing and gasket, and vacuum pump from the left-hand end of the cylinder head. Also if necessary unbolt the coolant cover and gasket from the right-hand end of the head. Note the location of brackets (see illustrations) 9 Using a soft metal drift, carefully lap out the left-hand side mount and recover the gasket (soe illustrations). 10 At tho timing bait end of the cylinder head.
6.8b Removing the thermostat housing ... 6.6 Removing the camshaft

2D*10 Engine removal and overhaul procedures
6.25 Checking the cylinder head for distortion 6.27 Checking the valve guides and valves for wear B.29a Diesel swirl chamber protrusion can be checked using a dial gauge...
scrape off the majority of the deposits with a blunt biade first, then use the wire brush. Caution: Do not erode the sealing surface ot the valve face. 23 Thoroughly clean the remainder of the components using solvent and allow them to dry completely. On 6-valve petrol and diesel engines, discard the oil seals, as new items must be fitted when the cylinder head is reassembled.
Inspection
Cylinder head 24 Inspect the head very carelully for cracks, evidence of coolant leakage, and other damage. If cracks are found, a new cylinder head should be obtained. 25 Use a straight-edge and feeler blade to check that the cylinder head gasket surface is not distorted (see illustration). If it is, it may
be
possible to have it machined, provided that Ihe cylinder head thickness is not excessively reduced. As no specifications as to permissible distortion limits or cylinder head thickness tolerances are given by ihe manufacturer, seek the advice of an engine overhaul specialist if distortion Is apparent. 26 Examine the valve seats In each of the combustion chambers, If they are severely pitted, cracked, or burned, they will need to be renewed or re-cut by an engine overhaul specialist. If they are only slightly pitted, this can be removed by grinding-in the valve heads and seats with fine valve-grinding compound, as described below.
27 Check the valve guides for wear by inserting the relevant valve, and checking for side-to-side motion of the valve (see illustration) A very small amount of movement Is acceptable. If the movement seems excessive, remove the valve. Measure the valve stem diameter at several points, and renew the valve if it is worn. If the valve stem is not worn, the wear must be In the valve guide, and the guide must be renewed. The renewal of valve guides should be earned out by an engine overhaul specialist, who will have the necessary tools required. 26 If renewing the vaive guides, the valve seats should be re-cut or re-ground only after the new guides have been fitted. 29 On diesel engines, inspect the swirl chambers for burning or damage such as cracking. Smalt cracks in the chambers are acceptable: renewal of the chambers will only be required if chamber tracts are badly burned and disfigured, or if they are no longer a tight fit in the cylinder head. If there is any doubt as to the swirl chamber condition, seek the advice of a Flat dealer or a suitable repairer who specialises in diesel engines. Swirl chamber renewal should be entrusted to a specialist. Using a dial test indicator, check that the difference between the swirl chamber and the cylinder head surface is within the limits given in Ihe Specifications. Alternatively feeler blades and a straight-edge may bo used (see illustrations). Zero the dial test indicator on the gaskel surface of tho cylinder head, then measure the protrusion of the swirl
chamber, if the protrusion is not within the specified limits, the advice of a Fiat dealer or suitable repairer who specialises in diesel engines should be sought. Camshaft 30 Inspect the camshaft for wear on the surfaces of the lobes and journals. Normally their surfaces should be smooth and have a dull shine: look for scoring and pitting. Accelerated wear will occur once the hardened exterior of the camshaft has been damaged. 31 Examine the bearing cap and journal surfaces for signs of wear. 32 To measure the camshaft endfloat, temporanly refit the camshaft then push the camshaft lo one end of the cylinder head as far as It will travel. Attach a dial test indicator to the cylinder head and zero it, then push the camshaft as far as It will go to the other end of the cylinder head and record the gauge reading. Verify the reading by pushing the camshaft back to its original position and checking that the gauge indicates zero again (see Illustration). 33 The camshaft bearing running clearance may be checked using Plastigauge as described later in this Chapter. 34 Where the camshaft and bearings are worn excessively consider renewing the complete cylinder head together with camshaft and cam followers. A reconditioned head may be available from ongine repairers. Wear of cam followers may be checked using a micrometer (see illustration).
6.29b ... or feeler blades 6.32 Chocking the camshaft endfloat with a dial gauge 6.34 Checking the wear of the cam followers

2D*10 Engine removal and overhaul procedures
65 On diesel engines. (It new O-ring seals to the vacuum pump then refit it to the left-hand end of the cylinder head and tighten the nuts (see illustrations). 96 Refit the camshaft sprocket with reference to Chapter 2A or 2C. 57 Refit the spark plugs, glow plugs and nfectors as applicable. 58 If required, refit the inlet and exhaust manifolds at this point. The valve clearances can also be checked now. The cylinder head is now ready for refitting as described In Part A, B or C of this Chapter (as applicable).
7 Pistons and connecting rods -removal, Inspection, and big- ^ end running clearance check ^
7.6a Unscrew the bolts.
8.54a Fitting a new oil seal to the right-hand side mount 6.54b Coolant cover gasket
Removal 1 Remove the sump and gasket with reference to Chapter 2A, 2B or 2C. 2 Unbolt and remove the oil pump pick-up/lilter screen assembly. On 16-valve engines, unbolt ond remove the anti-vibration ptate from the main bearing caps. 3 The big-end bearing shells can be renewed without having to remove the cylinder head, If the caps are unbolted and the piston/ connecting rod pushed gently up the bore slightly (the crankpin being at Its lowest point). It ihe3e shells are worn, however, the main bearing shells will almost certainly be worn as well. In this case. Ihe crankshaft should be removed for inspection. 4 To remove the pistons and connecting
6.55a Fitting a now large O-ring on the vacuum pump rods, remove the cylinder head first with reference to Chapter 2A, 2B or 2C. 5 Check to see if the big-end caps and connecting rods are numbered. If no numbers are visible, use a hammer and centre-punch, paint or similar, to mark each connecting rod and big-end cap with its respective cylinder number on the flat machined surface provided. 6 Turn the crankshaft as necessary to bring the first crankpin to its lowest point, then unscrew the bolts and remove the big-end cap and shell bearing (see illustrations). 7 Push the piston/rod assembly up the bore and out of the cylinder block. There is one reservation; if a wear ndge has developed at the top of the bores, remove this by careful scraping before trying to remove the piston/rod assemblies. Tho ridge will otherwise prevent removal, or wilt broak the piston nngs during the attempt.
.55b Fitting the vacuum pump • note the small O-ring on the end of the shaft 6 Remove the remaining pistons/rods In a similar way. If the boaring shells are to be used again, tape them to their respective caps or rods (see illustrations).
Inspection 9 Before the inspection process can begin, the piston/connecting rod assemblies must be cleaned, and the original piston rings removed from the pistons. 10 Carefully expand the old rings over the top of the pistons. The use of two or three old feeler blades will be helpful In preventing the rings dropping into empty grooves. Be careful not to scratch the piston with the ends of the nng. The rings are brittle, and will snap if they are spread too tar. They are also very sharp -protect your hands and fingers. Always remove the rings from the top of the piston. Keep each set of nngs with its piston If the old rings are to be re-used.
.. and remove the big-end cap and shell bearing
7.8a Connecting rod and cap (diesel engine) showing cylindor numbering (A) and shell location tags (B) 7.8b Connecting rod and cap numbers (petrol engine)

Apply a smear of clean engine oil to the gudgeon pin. Slide it Into the piston and through the connecting rod small-end. Check that the piston pivots freely on the rod. then secure the gudgeon pin in position with two new circlips. Ensure that each circlip is correctly located In Its groove in the piston.
Refitting and big-end bearing running ciearance check 27 Prior to refitting the piston/connecting rod assemblies, it Is recommended that the big-end bearing running clearance is checked as follows. Big-end bearing running clearance check 28 Clean the backs of the bearing shells, and the bearing locations in both the connecting rod and bearing cap. 29 Press the bearing shells into their locations, ensuring that the tab on each shell engages in the notch In the connecting rod and cap. Take care not to touch any shell's bearing surface with your fingers. If the onginal bearing shells are being used for the check, ensure that they are refitted in their original locations. The clearance can be checked in either of two ways. 30 One method is to refit the big-end bearing cap to Ihe connecting rod, ensuring that they are litted the correct way around, with the bearing shells in place. Wilh the cap retaining bolls correctly tightened, use an internal micrometer or vernier caliper to measure the internal diameter of each assembled pair of bearing shells. If the diameter of each corresponding crankshaft journal is measured and Ihen subtracted from the bearing internal diameter, the result will be the big-end beanng running clearance. 31 The second, and more accurate method is to use a product called Plasligauge. Ensure that the bearing shells are correctly fitted then place a strand of Plastlgauge on each (cleaned) crankpin journal. 32 Refit the (clean) piston/connecting rod assemblies to the crankshaft, and refit the bg-end bearing caps, using the marks made or noted on removal to ensure that they are fitted the correct way around. 33 Tighten the beanng cap bolts taking care not to disturb the Plastlgauge or rotate the connecting rod dunng the tightening sequence. 34 Dismantle the assemblies without rotating the connecting rods. Use the scale pnnted on the Plastigauge envelope to obtain the big-end bearing running clearance. 35 If the clearance is significantly different from that expected, the bearing shells may be Ihe wrong size (or excessively worn. If the original shells are being re-used). Make sure mat no dirt or oil was trapped between Ihe bearing shells and the caps or block when the clearance was measured. If the Plastigauge was wider al one end than at the other, the crankshaft journal may be tapered.
2D*10 Engine removal and overhaul procedures
7.40a The arrow on the piston crown must point towards the timing belt end of the engine (petrol engine) 36 On completion, carefully scrape away all traces of the Plastigauge material from the crankshaft and bearing shells. Use your fingernail, or some other object which is unlikely to score the beanng surfaces.
Final piston/connecting rod refitting 37 Ensure that the bearing shells are correctly fitted. If new shells are being fitted, ensure that alt traces of the protective grease are cleaned off using paraffin. Wipe dry the shells and connecting rods with a lint-free cloth. 38 Lubricate the cylinder bores, the pistons, and piston rings, then lay out each piston/con-necting rod assembly in its respective position. 39 Start with assembly No 1. Position the piston ring gaps 120° apart, then clamp them in position with a piston nng compressor. 40 Insert Ihe piston/connecting rod assembly into the top of cylinder making sure it is Ihe correct way round. On petrol engines, ensure that the arrow on the piston crown is pointing towards the timing belt end of the engine and on diesel engines, ensure that the cloverleaf-shaped cut-out on the piston crown is towards the front (oil filter side) of the cylinder block. Using a block of wood or hammer handle against the piston crown, tap the assembly into the cylinder until the piston crown is Hush with the top of the cylinder (sea illustrations). 41 Ensure that the bearing shell is still correctly Installed. Liberally lubricate the crankpin and both bearing shells. Taking care not to mark the cylinder bores, pull the piston/connecting rod assembly down the bore and onto the crankpin.
7.40b Inserting the piston/connecting rod assembly into the cylinder bore using a hammer handle (diesel englno) 42 Refit the big-end beanng cap, tightening Its retaining bolts finger-tight at first, Note that Ihe faces with the identification marks must match (which means that the bearing shell locating tabs abut each other). 43 Tighten the bearing cap retaining bolts evenly and progressively to the specified torque setting. On diesel engines tighten the bolts to the Stage 1 torque then angle-tighten them to the specified Stage 2 angle using an angle-measuring gauge, (see illustrations) 44 Once the bearing cap retaining bolts have been correctly tightened, rotate the crankshaft. Check that il turns freely; some stiffness is to be expected if new components have been fitted, but there should be no signs of binding or tight spots. 45 Refit the remaining three piston/ connecting rod assemblies in the same way. 46 Refit the cylinder head, anti-vibration plate (16-valve engines), oil pump pick-up/filter screen assembly and sump with reference to Chapter 2A, 2B or 2C.
8 Crankshaft -removal and inspection 35
Removal 1 Remove the
sump,
oil pump and pick-up tube, and flywheel/driveplate with reference to the relevant Sections of Chapter 2 Parts A, 8 or C. On 16-valve engines, unbolt and remove the anti-vibration plate from the main bearing caps.
7.43a Torque-tightening the big-end bearing cap bolls (diesel engine) 7.43b Angle-tightening the big-end bearing cap bolts (diesel engine)

2D*10 Engine removal and overhaul procedures
failure, (he cause must be corrected (where applicable) before the engine is reassembled, to prevent it from happening again. 3 When examining the bearing shells, remove them from the cylinder block/crankcase, Ihe main bearing caps, the connecting rods and the connecting rod big-end bearing caps. Lay them out on a clean surface in the same general position as their location in the engine. This will enable you to match any bearing problems with the corresponding crankshaft journal. Do not touch any shell's bearing surface with your fingers while checking it. 4 Din and other foreign matter gets into the engine in a variety of ways. It may be left in the engine during assembly, or It may pass through fillers or the crankcase ventilation system. It may get into the oil, and from there into the bearings. Metal chips from machining operations and normal engine wear are often present. Abrasives are sometimes left In engine components after reconditioning, especially when parts are not thoroughly cleaned using the proper cleaning methods. Whatever the source, these foreign objects often end up embedded In the soft bearing material, and are easily recognised. Large particles will not embed in the bearing, and will score or gouge the bearing and journal. The best prevention for this cause of bearing failure Is to clean all parts thoroughly, and keep everything spotlessly-clean during engine assembly. Frequent and regular engine oil and filter changes are also recommended. 5 Lack of lubrication (or lubrication breakdown) has a number of interrelated causes. Excessive heat (which thins the oil), overloading (which squeezes the oil from the bearing face) and oil leakage (from excessive bearing clearances, worn oil pump or high engine speeds) all contribute to lubrication
breakdown. Blocked oil passages, which can be the result of misaligned oil holes in a bearing shell, will also oil-starve a bearing, and destroy it. When lack of lubrication is the cause of bearing failure, the bearing materiel is wiped or extruded from the steel backing of Ihe bearing. Temperatures may increase to the point where the steel backing turns blue from overheating. 6 Driving habits can have a definite effect on bearing life. Full-throttle, low-speed operation (labouring ihe engine) puts very high loads on bearings, tending to squeeze out the oil film. These loads cause the beanngs to flex, which produces fine cracks in the bearing face (fatigue failure). Eventually, the bearing material will loosen in pieces, and tear away from Ihe steel backing. 7 Short-distance driving leads to corrosion of bearings, because insufficient engine heat is produced to drive off the condensed water and corrosive gases. These products collect in the engine oil, forming acid and sludge. As the oil Is carried to the engine bearings, the acid attacks and corrodes the bearing material. 8 Incorrect bearing installation during engine assembly will lead to bearing failure as well. Tight-fitting bearings leave insufficient bearing running clearance, and will result in oil starvation. Dirt or foreign particles trapped behind a bearing shell result in high spots on the bearing, which lead to failure. 9 Do not touch any shell's bearing surface with your fingers during reassembly: there is a risk of scratching the delicate surface, or of depositing particles of dirt on ft. 10 As mentioned at the beginning of this Section, the bearing shells should be renewed as a matter of course during engine overhaul; to do otherwise is false economy.
Selection 11 Main and big-end bearings are available in standard sizes and a range of undersizes to suit reground crankshafts • refer to the Specifications for details. The engine reconditioner will select the correct bearing shells for a machined crankshaft. 12 The running clearances can be checked when the crankshaft is refitted with its new bearings.
11 Engine overhaul -reassembly sequence
1 Before reassembly begins, ensure that all new parts have been obtained, and that all necessary tools are available. Read through the entire procedure to familiariss yourself with the work Involved, and to ensure that ail items necessary for reassembly of the engine are at hand. In addition to all normal tools and materials, thread-locking compound will be needed. A tube of sealant will also be required for the joint faces that are fitted without gaskets.
2 In order to save time and avoid problems, engine reassembly can be carried out in the following order: a) Crankshaft (Section 12). b) Piston/connecting rod assemblies (Section 7). c) Oil pump (see Part A, B or C - as applicable). d) Sump (see Pan A, BorC-as applicable). e) Flywheel/driveplate (see Part A, B or C • as applicable). 1) Cylinder head (see Part A B or C - as applicable). g) Coolant pump (see Chapter
3)
h) Timing belt tensioner and sprockets, and timing belt (See Part A, B or C- as applicable). I) Engine external components, 3 At this stage, ail engine components should be absolutely clean and dry, with all faults repaired. The components should be laid out on a completely clean work surface.
12 Crankshaft- % refitting and main bearing S running clearance check ^
Crankshaft - initial refitting 1 Crankshaft refitting Is the first stage ol engine reassembly following overhaul. At this point, it is assumed that the crankshaft, cylinder block/crankcase and beanngs have been cleaned, inspected and reconditioned or renewed. 2 Place the cylinder block on a clean, level work surface, with the crankcase facing upwards. Where necessary, unbolt the bearing caps and lay them out in order to ensure correct reassembly. If they are still in place, remove the bearing shells from the caps and the crankcase and wipe out the inner surfaces wilh a clean rag - they musl be kept spotlessly clean. 3 Clean the rear surface of the new bearing shells with a rag and fit ihem on Ihe bearing saddles. Ensure that the orientation lugs on the shells engage with the recesses in the saddles and lhat the oil holes are correctly aligned. Do not hammer or otherwise force the bearing shells into place. It Is critically important that the surfaces of the bearings ore kept free from damage and contamination. 4 Give the newly fitted bearing shells and the crankshaft journals a final clean with a rag. Check that the oil holes In the crankshaft are free from dirt, as any left here will become embedded In the new bearings when Ihe engine is first started. 5 Carefully lay the crankshaft In the crankcase, taking care not to dislodge the bearing shells (see illustration}.
Main bearing running clearance check 8 When Ihe crankshaft and bearings are refitted, a clearance must exist between them