Temperature FIAT PUNTO 1994 176 / 1.G User Guide

2B*7 DOHC (16-valve) petrol engine in-car repair procedures
35 Slacken the tensioner pulley retaining nut and reposition the tensioner to align the
mobile
indicator with the fixed reference mark
on the
pulley face (see illustration). Hold the
pdley in
this position and tighten the retaining
nut to the
specified torque. 36 Turn the crankshaft through a further two complete turns In the normal direction of rotation. Check that the timing is correct by alining Ihe piston positioning tools and
camshaft
locking tools as described previously. 37 When all is correct, remove the setting rri
locking
tools and refit the sealing plugs to 1ft© cylinder head extension, using new 0-
nr^s if
necessary. Tighten the plugs securely. 38 Refit the spark plugs as described in Chapter 1A. 39 Refit Ihe ECU and secure with Ihe mooning bolts. 40
Renew the
injector O-ring seals, smear them Kith
8 little
Vaseline then locate the injectors and tef rail onto the inlet manifold lower section.
Saute Ihe fuel rail
with the two retaining bolts. 41 Relit the inlet manifold upper section using new sealing O-rlngs If necessary and
sectre
with the two bolts. 42 Reconnect the wiring connectors for the tot injector harness and the intake air temp-erature/pressure sensor, then connect the fuel pressure regulator vacuum hose and tha
EVAP
purge valve hose. 43 Reconnect the wiring connectors for the ihrottls potentiometer, idle control stepper motor and coolant temperature sensor. Reconnect the brake servo vacuum hose. 44 Refit and adjust the accelerator cable as described in Chapter 4B. 46 Refit the upper and lower timing belt
covers
together with the TDC sensor wiring. 46 Refit the crankshaft pulley and tighten the
three
retaining bolts securely. 47 Refit the air cleaner. Inlet air duct and resonator as described in Chapter 4B. 48
Refit
tha auxiliary drivebelt(s) as described i/t Chapter 1A, then reconnect the battery
S Timing belt tensioner
and
sprockets -
removal
and refitting

Timing
belt tensioner
Removal I
Remove
the timing belt as described in
Section
4. 1 Completely unscrew the tensioner nut and Wiethe tensioner off the mounting stud-Inspection
3 Wipe
the tensioner clean but do not use Kfrents that may contaminate the bearings.
Spin
the tensioner pulley on its hub by hand.
Sfcfl
movement or excessive freeplay is an rcfceticn of severe wear: the tensioner is not 3 serviceable component, and should be nnewsd.
4.33 Holding the camshaft sprocket with the tool described previously while tightening the sprocket bolt Refitting 4 Slide the tensioner pulley over the mounting stud and fit the securing nut. 5 Refit the timing belt as described in Section 4. Camshaft sprocket Removal 6 Remove the timing belt as described in Section 4. 7 Unscrew the bolt and slide the sprocket from the end of the camshaft. Inspection 8 With the sprocket removed, examine the camshaft oil seal for signs of leaking. If necessary, refer to Section 6 and renew it. 9 Check the sprocket teeth for damage. 10 Wipe clean the sprocket and camshaft mating surfaces. Refitting 11 Locate the sprocket on the end of the camshaft, then refit the retaining boll finger tight only at this stage. 12 Refit the timing belt as described in Section 4.
Crankshaft sprocket Removal 13 Remove the timing bell as described In Section 4. 14 Working beneath the engine, unbolt and remove the flywheel lower cover, then hold the flywheel stationary preferably using a tool which engages the flywheel starter ring
<

Alternatively have an assistant engage a wide-bladed screwdriver with the starter ring gear. 15 Unscrew the crankshaft sprocket retaining bolt and slide the sprocket off the end of the crankshaft. The sprocket may have an integral location key on its inner face, or a separate key which locates In a groove in the crankshaft nose may be fitted. Inspection 16 With the sprocket removed, examine the crankshaft oil seal for signs of leaking. If necessary, refer to Section 7 and renew it. 17 Check the sprocket teeth for damage. 18 Wipe clean the sprocket and crankshaft mating surfaces. Refitting 19 Slide the sprocket onto the crankshaft making sure
11
engages the integral key or separate key, then refit the bolt and washer and tighten the bolt to the specified torque while holding the crankshaft stationary using the method described in paragraph 14. 20 Refit the timing belt as described in Section 4.
6 Camshaft
oil
seal -renewal
1 Remove the timing belt and camshaft sprocket as described in Sections 4 and 5. 2 Punch or drill a small hole in the oil seal. Screw a self-tapping screw into the hole, and pull on the screws with pliers to extract the seal. 3 Clean the seal housing, and polish off any burrs or raised edges, which may have caused the seal to fall in the first place. 4 Lubricate the lips of the new seal with clean engine oil, and drive it into position until It seats on its locating shoulder. Use a suitable tubular drift, such as a socket, which bears only on the hard outer edge of the seal. Take care nof to damage the seal lips during fitting. Note that the Seal lips should face inwards. 5 Refit the camshaft sprocket and timing belt as described in Sections 5 and 4.
7 Crankshaft oil seats -renewal I
4.35 Position the tensioner so that the mobile Indicator (1) is aligned with the fixed reference mark (2)
Front (right-hand side) oil seal 1 The front oil seal is located in the oil pump on the front of the crankshaft. Remove the timing belt as described in Section 4 and the crankshaft sprocket as described in Section 5. 2 Using a hooked Instrument, remove the oil seal from the oil pump casing taking care not to damage the surface of the crankshaft. 3 Clean the seating in the housing and the surface of the crankshaft. To prevent damage to the new oil seal as it is being fitted, wrap some adhesive tape around the end of the crankshaft and lightly oil it.

DOHC (16-valve) petrol engine in-car repair procedures 2B*11
camshaft cover plate... 25 Locate the cam follower retaining tools in position and refit the cylinder head extension
as
described In Section 8.

10
Cylinder head - &
removal and
refitting S
Removal Note; The cylinder head bolts are of special
sekned
design and a Fiat tool should be
obtained
to unscrew them. A Ton key will not
JSt however
in practise It was found that a dose-httlng Alien key could be used as an itemative. 1 Drain the cooling system as described in Chapter 1A. 2 Remove the cylinder head extension as oescAbed
m
Section 8. 3 Disconnect the radiator hose from the thermostat housing on the left-hand end of
Ihe
cylinder head. 4 Disconnect the heater hose from the outlet
at the
rear of the cylinder head. 5 Disconnect the coolant temperature sensor md temperature gauge sensor wiring plugs
torn
the left-hand end of the cylinder head. 9 Undo the engine oil dipstick tube bracket retaining bolt and the two bolts securing the wing harness support clips to the inlet marriold lower section. 7 Undo Ihe retaining nuts and separate the ixhaust system front pipe from the exhaust manifold flange.
8
Check that nothing remains attached to the cinder head likely to impede removal. It Is assumed that the head will be removed complete with exhaust manifold and inlet manifold lower section. 9 Unscrew the cylinder head bolts half a turn K
e
time in the reverse order to that shown in (lustration 10.20a. When the bolts are free. «mwe them from their locations.. Id Lift the cylinder head from the block. If it is stuck tight rock the head to break the joint by mans of the manifolds. On no account drive
levers
into the gasket Joint, nor attempt to tap tf« head sideways, as it is located on positioning dowels. 11 Remove and discard the cylinder head gasket.
JK'
l^. 9.22b ... then apply RTV gasket sealant to the cover plate contact face 12 Refer to Chapter 20 for cylinder head dismantling and inspection procedures. Preparation for refitting 13 The mating faces of the cylinder head and cylinder block must be perfectly dean before refitting the head. Use a hard plastic or wooden scraper to remove all traces of gasket and carbon; also clean the piston crowns, Take particular care when cleaning the piston crowns as the soft aluminium alloy is easily damaged. Make sure that the carbon is not allowed to enter the oil and water passages -this Is particularly important for the lubncahon system, as carbon could block the oil supply to the engine's components. Using adhesive tape and paper, seal the water, oil and bolt holes in the cylinder block. To prevent carbon entering the gap between the pistons and bores, smear a little grease In the gap. After cleaning each piston, use a small brush to remove all traces of grease and carbon from the gap. then wipe away the remainder with a clean rag. Clean all the pistons in the same way. 14 Check the mating surfaces of the cylinder block and the cylinder head for nicks, deep scratches and other damage. If slight, they may be removed carefully with a file, but If excessive, machining may be the only alternative to renewal. If warpage of the cylinder head gasket surface Is suspected, use a straight-edge to check it for distortion. Refer to Part 0 of this Chapter if necessary. 15 Check the condition of the cylinder head bolts, and particularly their threads, whenever they are removed. Wash the bolts In a suitable
sequence
9.24 Lubricate the cam followers and place them in position in their respective bores solvent, and wipe them dry. Check each bolt for any sign of visible wear or damage, renewing them if necessary.
Refitting 18 Before refitting the assembled cylinder head, make sure that the head and block mating surfaces are perfectly clean, and that the bolt holes in the cylinder block have been mopped out to clear any oil, 17 The now gasket should not be removed from its nylon cover until required for use. Fit Ihe gasket dry, and make sure that the mating surfaces on the head and block are perfectly clean. 18 Place the gasket on the cylinder block so that the word ALTO can be read from above. 19 Lower the cylinder head onto the block so that it locates on the positioning dowel. 20 The cylinder head bolt threads must be clean and lightly lubricated. Screw the bolts in finger-tight then working progressively and in the sequence shown, lighten all the cylinder head bolts to the Stage 1 torquo setting given In the Specifications, using a torque wrench and a suitable socket. With all the bolts tightened to their Stage 1 setting, working again in the specified sequence, first angle-tighten the bolts through the specified Stage 2 angle, then again through the Stage 3 angle, using a socket and extension bar. It Is recommended that an angle-measuring gauge Is used during this stage ot tightening, to ensure accuracy (see Illustrations). 21 Reconnect the exhaust system front pipe to the manifold using a new flange gasket.
10.20b Tighten the cylinder head bolts to the Stago 1 torque setting ...

2B*12 DOHC (16-valve) petrol engine in-car repair procedures
... then through the Stage 2 end Stage 3 angle
22 Refit the engine oil dipstick tube bracket retaining bolt and the two bolts securing the wiring harness support clips to the inlet manifold lower section. 23 Connect the coolant temperature sensor and temperature gauge sensor wiring plugs. 24 Connect the radiator hose lo the thermostat housing and the heater hose to the cylinder head outlet. 25 Refit the cylinder head extension as described in Section 8. 26 On completion, refill tha cooling system as described In Chapter 1A.
11 Flywheel -removal, Inspection arid refitting
12 Engine mountings -inspection and renewal
Refer to Chapter 2A, Section 11.
13 Sump -removal and refitting
R6fer to Chapter 2A. Section 12.
14 Oil pump and pick-up tube -removal, Inspection and refitting
Refer to Chapter 2A, Section 10. Refer to Chapter 2A. Section 13.

2C*2 Diesel engine in-car repair procedures
4.4a Unbolt the engine oil dipstick tube...
3 Cylinder compression test
Note: A compression tester specifically designed for diesef engines must be used for this test. 1 When engine performance Is down, or if misfiring occurs, a compression test can provide diagnostic clues as to the engine's condition, If the lest is performed regularly, it can give warning of trouble before any other symptoms become apparent. 2 A compression tester specifically Intended for diesel engines must be used, because of the higher pressures involved. The Ie6ter is connected to an adapler which screws Into the glow plug or injector hole. It is unlikely to be worthwhile buying such a tester for occasional use. but it may be possible to borrow or hire one • if not. have the test performed by a garage. 3 Unless specific instructions to the contrary are supplied with the tester, observe the following points: 9) The battery must bo in a good state of charge, the air titter must be clean, end the engine should be at normal operating temperature. b) AH the in/actors or glow plugs should be removed before starting the lest. If removing the injectors, also remove the flame shield washers, otherwise they may be blown out. c) The stop solenoid must be disconnected.
4.4b ... and remove it from the rubber grommet in the oil pump housing
fo prevent the engine from running or fuel from being discharged. 4 There is no need to hold the accelerator pedal down during the test, because the diesel engine air inlet is not throttled. 5 The cause of poor compression Is less easy to establish on a diesel engine than on a petrol one. The effect of introducing oil into the cylinders (wet testing) Is not conclusive, because there is a risk that the oil will sit in the recess on the piston crown, instead of passing to the rings. However the following can be used as a rough guide to diagnosis. 6 All cylinders should produce very similar pressures; a difference of more than 5 bars between any two cylinders Indicates the existence of a fault. Note that the compression should build up quickly In a healthy engine; low compression on the first stroke, followed by gradually-increasing pressure on successive strokes, indicates worn piston rings. A low compression reading on the first stroke, which does not build up during successive strokes, indicates leaking valves or a blown head gasket (a cracked hoad could also be the cause). 7 A low reading from two adjacent cylinders Is almost certainly due to the head gasket having blown between them: the presence of coolant In the engine oil will confirm this,
Leakdown test 8 A leakdown test measures the rate at which compressed air fed into the cylinder Is lost. It is an alternative to a compression test, and in many ways it is better, since the escaping air provides easy identification of where pressure loss is occurring (piston rings, valves or head gasket). 9 The equipment needed for leakdown testing is unlikely to be available to the home mechanic. If poor compression Is suspected, have the test performed by a suitably-equipped garage.
4 Timing belt and covers -removal
and
refitting
Note: Fiat specify the use of a spec/a/ timing belt tension measuring tool to correctly set the timing belt tension. If access to this equipment cannot be obtained, an approximate setting can be achieved using the method described below. If the method described is used, the tension must be checked using the special tool at the earliest possible opportunity. Do not drive the vehicle over large distances, or use high engine speeds, until the belt fens/on rs known to be correct. Refer to a Fiat dealer for advice.
General Information 1 The function of the timing belt is to drive the camshaft and fuel injection pump. Should the belt slip or break in service, the valve timing will be disturbed and piston-to-valve contact
will occur, resulting In serious engine damage. 2 The timing bolt should be renewed at the specified intervals (see Chapter 1B), or earlier If It is contaminated with oil. or If It is at al noisy In operation (a scraping noise due to uneven wear),
Removal 3 Set the engine at TDC on No 1 cylinder
as
described in Section 2. 4 Unbolt and remove tho engine oil dipstick tube and remove It from the rubber gromme! in the oil pump housing (see illustrations), 5 Before removing the timing belt check rts tension by turning the belt through 90" with finger and thumb midway between u* injection pump and camshaft sprockets. This will give you an Idea of the tension to apply when refitting, assuming the tension is already correct. Also note the position of the tensions pulley as a reference mark. 6 Release tho nut on the timing bea tensioner, move the tensioner pulley away from the belt and retlghten the nut to hold the pulley in the retracted position. 7 If the timing belt is to be re-used, use white paint or chalk to mark the direction of rotation on the belt (if markings do not already exist), then slip the belt off the camshaft, crankshaft and injection pump sprockets, and the idler and tensioner pulleys. Caution: If the belt appears to be In good condition and can be re-used, it fs essential that It Is refitted the same
wsy
round, otherwise accelerated wear will result, leading fo premature failure. 8 Check the timing belt carefully for any signs of uneven wear, splitting, or oil contamination. Pay particular attention to the roots of the teeth. Renew it if there is the slightest doutt about its condition. If the engine is undergoing an overhaul, renew the belt as a matter of course, regardless of its apparent conditio*. The cost of a new belt Is nothing compa/ed with the cost of repairs, should the belt freak in service. If signs of oil contamination art found, trace the source of the oil leak and rectify It. Wash down the engine timing baft area and all related components, to remove
sd
traces of oil.
Refitting 9 Before refitting, thoroughly clean the tknmg belt sprockets. Check that the tensioner and idler pulleys rotate freely, without any sign ol roughness. If necessary, renew them as described in Section 5. 10 Ensure that the crankshaft, camshaft and injection pump sprockets are still at their TDC positions as described In Section 2. 11 Engage the timing belt with the crankshaft sprocket, then locate it around the idler pufiey and onto the Injection pump sprocket making sure that it is kept taught. Continue to locate! around the camshaft sprocket and finally around Ihe tensioner pulley (see Illustration) Ensure the belt teeth seat correctly on Ihe sprockets.

Diesel engine in-car repair procedures
2C*11

9.15 Short coolant hose from the cylinder head outlet to the coolant pump 19 Where applicable, unscrew the bolts retaining the bracket to the turbocharger and thecrankcase (see illustration). 20 Unscrew the nut and slide the timing belt tensioner off Its stud.
9,17 Disconnecting the return hose from the thermostat housing
9.18a Metal coolant rotum pipe mounting bolt
injection pump
9.16a Disconnecting the oil delivery pipe from the turbocharger 21 Release the fuel supply and return hoses from the supports on the cylinder head. 22 Unscrew the union bolt and disconnect the fuel supply hose from the filter on the bulkhead. 23 Loosen the clip and disconnect the fuel return hose from the injection pump. 24 Unscrew Ihe union nuts while holding insert fiats, and disconnect the fuel supply lines from the Injectors and injection pump (soo illustration). Cover tho apertures to prevent dust entry. 25 Disconnect the glow plug supply wiring from the terminal on No 4 glow plug heater on the front left-hand side of the engine. 26 Disconnect the wiring from the maximum coolant temperature connector on the front of the engine. 27 Disconnect the fuel return line from No 1 Injector.
9.18b Removing the metal coolant return pipe from the coolant pump
9.31a Bolts securing the inner timing cover to the cyllndor head
9.16b Oil delivery pipe location on the crankcase 28 Unscrew the nuts securing the exhaust front pipe to the exhaust manifold. Where necessary, use a screwdriver to bend back the lock tabs. Lower the front pipe and recover the gasket. 29 Where applicable, remove the clip and disconnect the oil return hose from the turbocharger to the sump. 30 Remove the camshaft sprocket as described in Section 5. 31 Unscrew the bolts securing the timing belt inner cover to the cylinder head and injection pump bracket, then remove the inner cover (see illustrations). 32 Unbolt and remove the camshaft cover and recover the gasket. Note the location of the support brackets. 33 Unscrew and remove the bolts and washers located on the front of the cylinder head, alongside the injectors (see illustration),
9.19 Unbolt the bracket retaining the turbocharger and manifold to the crankcase
9.31b Removing the bolts securing the Inner timing cover to the injection pump/oll Alter bracket

2D*10 Engine removal and overhaul procedures
4.50b ... and expansion tank 4.S2 Disconnecting the radiator coolant temperature sensor wiring plug
4.53b One of tho wheel arch liner retaining screws is hidden in a recess 52 On the radiator cooling fan housing, disconnect the wiring plug for tho coolant temperature sensor (see illustration). 53 Unscrew the four front screws on each side retaining the wheel arch liners in order to
4.53c Bolt securing the front bumper to the valance access the front bumper mounting bolts • one of lite screws is hidden in a recess. Pull back the liners and use an extension and socket to unscrew the bolts securing the front bumper to tho valance (see illustrations).
4.55 Releasing the retaining clips from the rear of tho indicator lights 4.56a Side bumper retaining screw
4.56b Centre bumper retaining screw 4.57a Radiator lower mounting bracket bolt
4.54 One of the front bumper lower retaining screws 54 Unscrew and remove the front bumper lower retaining screws (see Illustration). 55 From inside the engine compartment, disconnect the wiring from the rear of the Indicator lights and release the retaining clips (see illustration). 56 Unscrew the upper retaining screws and withdraw the front bumper from the body (see Illustrations). 57 Unscrew the bolts socunng the radiator lower mounting bracket to the body then prise the bracket from the rubbers on the bottom ol the radiator (see Illustrations). 58 Unscrew the upper mounting bolt securing the engine oil cooler then lower the cooler and support on an axle stand (see illustrotion). Take care not to damage the hoses. 59 Support the radiator then unscrew the radiator upper mounting bolts, and remove the radiator from the vehicle (see illustrations).
4.57b Removing the bracket from the rubbers on the bottom of the radiator

2D*10 Engine removal and overhaul procedures
7.13 Positioning of piston rings (petrol engine) 11 Scrape away all traces of carbon from the top of the piston. A hand-held wire brush (or a piece of fine emery cloth) can be used, once the majority ot the deposits have been scraped away. 12 Remove the carbon from the ring grooves In the piston, using an old ring. Break the ring in half to do this (be careful not to cut your fingers - piston rings are sharp). Be careful to remove only the carbon deposits • do not remove any metal, end do not nick or scratch the sides of the ring grooves. 13 Once the deposits have been removed, clean the piston/connecting rod assembly with paraffin or o suitable solvent, and dry thoroughly. Make sure that the oil return holes In the ring grooves are clear. Fit the rings to their respective grooves meking sure they are positioned the correct way round where applicable (see illustration). 14 If the pistons and cylinder bores are not
7.22 Prising out the gudgeon pin retaining circilps damagea or worn excessively, and if the cylinder block does not need to be rebored. the original pistons can be refitted. Normal piston wear shows up as even vertical wear on the piston thrust surfaces, and slight looseness of the top ring In its groove. New piston rings should always be used when the engine is reassembled. 15 Carefully inspect each piston for cracks around the skirt, around the gudgeon pin holes, and at the piston nng lands (between the ring grooves). 16 Look for scoring and scuffing on the ptston skirt, holes in the piston crown, and burned areas at the edge of the crown. If the skirt is scored or scuffed, the engine may have been suffering from overheating, end/or abnormal combustion which caused excessively high operating temperatures. The cooling and lubrication systems should be checked thoroughly. Scorch marks on the sides of the pistons show that blow-by has occurred. A hole in the piston crown, or burned areas at the edge of the piston crown, Indicates that abnormal combustion has been occurring. If any of the above problems exist, the causes must be investigated and corrected, or the
7.26a Piston to connecting rod assembly (petrol engine) 1 Piston grade (A) end directional arrow on piston crown (towards timing belt end) 2 Connecting rod/cap matching numbers 3 Gudgeon pin offset in piston (0.9 to 1.1 mm) Arrow indicates direction of crankshaft rotation
7.26b Piston to connecting rod assembly (diesel engine) 1 Piston crown
damage will occur again. The causes may Include Incorrect Ignition/injection pump timing, or a faulty injector (as applicable). 17 Corrosion of the piston, in the form ol pitting, indicates that coolant has been leaking into the combustion chamber and/or the crankcase. Again, the cause must be corrected, or the problem may persist In the rebuilt engine. 16 Examine each connecting rod carefully for signs of damage, such as cracks around the big-end and small-end bearings. Check that the rod is not bent or distorted, Damage is highly unlikely, unless the engine has been seized or badly overheated. Detailed checking of the connecting rod assembly can only be earned out by an engine repair specialist with the necessary equipment. 19 Although not essential. It is highly recommended that the big-end cap bolts are renewed as a complete set prior lo refitting. 20 On petrol engines piston and/or con-necting rod renewal should be entrusted to an engine repair specialist, who will have the necessary tooling to remove and install the interference fit gudgeon pins. 21 On diesel engines, the gudgeon pins are of the floating type, secured in position by two circlips. On these engines, the pistons and connecting rods can be separated as follows. 22 Using a small fiat-bladed screwdriver, prise out ihe circlips, and push out the gudgeon pin (see illustration). Identify the piston and rod to ensure correct reassembly. Discard the circlips - new ones must be used on refitting. 23 Examine the gudgeon pin and connecting rod small-end bearing bush for signs of wear or damage. Bush renewal should be entrusted to an engine overhaul specialist. 24 The connecting rods themselves should not be In need of renewal, unless seizure or some other major mechanical failure has occurred. Check the alignment of the connecting rods visually, and if the rods are not straight, take ihem to an engine overhaul specialist for a more detailed check. 25 Examine all components, and obtain any new parts as necessary. If new pistons are purchased, they will be supplied complete with gudgeon pins and circlips. 26 On reassembly position the piston on the connecting rod as shown (see Illustrations),
Injection pump location Connecting rod/cap matching numbers 7.28c Piston crown on diesel engines

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

3*1
Chapter 3
Cooling, heating and ventilation systems
Contents
Air conditioning system - general Information and precautions .... 9 Mr conditioning system components * removal and refitting 10 Antifreeze mixture See Chapter 1A or 1B Auxiliary drivebell(s) check and renewal See Chapter 1A or IB Coolant level check See Weekly checks Coolant pump - removal, Inspection and refitting 7 Coolant renewal See Chapter 1A or 1B
Degrees of difficulty
Cooling fan switch - testing, removal and refitting 6 Cooling system hoses • disconnection and renewal 2 Electric cooling fan(s) - testing, removal and refitting 5 General information and precautions 1 Heater/ventilation components • removal and refitting 8 Radiator - removal, inspection and refitting 3 Thermostat - removal, testing and refitting 4

Easy,
suitable foe JS^, novice
with
little experience ^
Fairly
easy,
sutable for beginner witti
some experience
^
Faiilydifltctit,
suitable
for competent
DIY mechanic
^

Difficult,
sutable for & experienced DIY « mechanic ^
VerydMlcult, ^
suitable
for
expert DIY
« or professional
Specifications
General Expansion tank relief valve opening pressure 0.96 bar Coolant pump Impeller-to-casing clearance: Diesel engine models 0.53 to 1.37 mm Petrol engine models 0.4 to 0.9 mm
Thermostat Diesel engine models: Opening temperature: Starts to open 78 to 82*0 Fully open 88°C Maximum valve travel (approximate) 7.5 mm Petrol engine models: Opening temperature: 1108 cc and 1242 cc (8-valve) engines: Starts to open 85 to 89°C Fully open 100°C 1242 cc (16-valve) engines: Starts to open 81 to 85°C Fully open 103°C Maximum valve lift (approximate) 7.5 mm
Electric cooling fan Petrol engine models with single speed fan: Cut-in temperature 90to94°C Cut-out temperature B5 to 89°C Diesel engine models with twin speed fan: Cut-In temperature: Primary fan 86 to 90® C Secondary fan 90 to 94°C Cut-out temperature: Primary fan 81to85°C Secondary fan 85 to 89°C
Torque wrench settings Nm tbfft Coolant pump pulley securing bolts (diesel engine models) 23 17 Coolant pump securing bolts: Diesel engine models 23 17 Petrol engine models 8 6 Coolant pump securing nuts (petrol engine models) 10 7

3*2 Cooling, heating and ventilation systems
1 General information and precautions
Genera/ Information The engine cooling/cabin heating system is ol pressurised type, comprising a coolant pump driven by the camshaft timing belt (petrol engine models) or auxiliary drlvebelt (diesel engine models), a crossllow radiator, a coolant expansion tank, an electric cooling fan, a thermostat, heater matrix, and all associated hoses and switches. The system functions as follows: Ihe coolant pump circulates cold water around the cylinder block and head passages, and through the Inlet manifold, heater matrix and throttle body to the thermostat housing. When the engine Is cold, the thermostat remains closed and prevents coolant from circulating through the radiator. When the coolant reaches a predetermined temperature, the thermostat opens, and the coolant passes through the top hose to the radiator. As the coolant circulates through the radiator, it is cooled by the in-rush of air when the car is in forward motion. The airllow is supplemented by the action of the electric cooling fan. when necessary, As the temperature of the coolant in the radiator drops, it flows to the bottom of the radiator by convection, and passes out through the bottom hose to the coolant pump - the cycle is then repeatod, When the engine is at normal operating temperature, the coolant expands, and some of It is displaced into the expansion tank. Coolant collects In the tank, and ts returned to Ihe radiator when the system cools. On petrol engine models, the expansion tank is integrated into the side of the radiator. On diesel engine models, and certain petrol engine models with air conditioning, the tank is a separate unit, mounted on the right hand side of the engine compartment. On turbo diesel engine models, the coolant is also passed through a supplementary engine oil cooler, to assist In controlling the engine lubricant temperature. Tho electric cooling fan mounted in front of the radiator is controlled by a thermostatic switch. At a predetermined coolant temperature, the swilch/sensor actuates the tan lo provide additional airflow through the radiator, The switch cuts the electrical supply to the Ion when the coolant temperature has dropped below a preset threshold (see Specifications).
Precautions

A


Warning: Do not attempt to remove the expansion tank pressure cap, or to disturb any part of the cooling system, whlio the engine is hot, as then is a high risk of scalding, tf the expansion tank pressure cap must be removed before the
engine and radiator have fulty cooled (even though this is not recommended?, the pressure in the cooling system must first be relieved. Cover the cap with a thick layer of cloth, to avoid scalding, and slowly unscrew the pressuro cap until a hissing sound Is heard. When the hissing stops, indicating that the pressure has reduced, slowly unscrew the pressure cap until it can be removed; If more hissing sounds are heard, wait until they have stopped before unscrewing the cap completely. At all times, keep your face well away from the pressure cap opening, and protect your hands.

A


Warning: Do not allow antifreeze to come into contact with your skin, or with the painted surfaces of the vehicle. Rinse off spills immediately, with plenty of water. Never leave antifreeze lying around in an open container, or In a puddle In the driveway or on the garage floor. Children and pets are attracted by its sweet smell, but antifreeze can be fatal tf ingested.

A


Warning: If the engine is hot, the electric cooling fan may start rotating even if the engine and ignition are switched off. Be careful to keep your hands, hair, and any loose clothing well clear when working In the engine compartment.
2 Cooling system hoses - f&> disconnection and renewal ^
1 The number, routing and pattern of hoses will vary according to model, but the same basic procedure applies. Before commencing work, make sure that the new hoses are to hand, along wilh new hose clips if needed, it is good practice to renew the hose clips at the same time as the hoses. 2 Drain the cooling system, as described in Chapter 1A or 18, saving the coolant if it is fit for re-use. Apply a little penetrating oil onto the hose clips if they are corroded. 3 Release the hose clips from the hose concerned. Three types of clip are used; worm-drive. spring and 'sardine-can'. The worm-drive clip is released by turning its screw anti-clockwise. The spring clip Is released by squeezing Its tags together with pliers, at the same time working the cbp away from the hose stub. The sardine-can clips are not re-usable, and are best cut off with snips or side cutters. 4 Unclip any wires, cables or other hoses which may be attached to the hose being removed. Make notes for reference when reassembling If necessary. 5 Release the hose from its stubs with a twisting motion. Be careful not to damage the stubs on deltcate components such as the radiator, or thermostat housings. If the hose Is stuck fast, the best course is often to cut it off using a sharp knife, but again be careful not to damage the stubs.
6 Before fitting the new hose, smear the stubs with washing-up liquid or a suitable rubber lubricant to aid fitting. Do not use oil or grease, which may attack the rubber. 7 Fit the hose clips over the ends of the hose, then fit the hose over its stubs. Work the hose Into position. When satisfied, locate and tighten the hose dips. 6 Refill the cooling system as described In Chapter 1A or 1B. Run the engine, and chock that there are no leaks. 9 Recheck the tightness of Ihe hose clips on any new hoses after a few hundred miles. 10 Top-up the coolant level if necessary.
3 Radiator -
removal,
inspection and refitting
Removal Note: If leakage is the reason for removing
the
radiator, bear In mind that minor leaks can often be cured using proprietary radiator sealing compound, with the radiator in situ. 1 Disconnect the battery negative terminal (refer to Disconnecting the battery In the Reference Section of this manual). On diesel engine models, unbolt the relay bracket from the side of the battery tray. 2 Drain the cooling system as described In Chapter 1A or 1B. 3 On 1242 cc (16-valve) petrol engine models, remove the air cleaner and Inlet ducts as desenbed In Chapter 4B, 4 Slacken the clips and disconnect Ihe (op and bottom coolant hoses from the radiator. In addition on diesel engine models, and petrol engine models with a remotely-sited expansion tank, disconnect the expansion tank coolant hose from the right hand side ol the radiator (see Illustrations), 5 Unscrew the fixings and lift the plastic trim panel from above the front bumper Unscrew the bolt(s) securing tho radiator to the upper body panel (see Illustration). Note that the radiator and cooling fan assembly share the same upper mounting bolt. 6 Unbolt the cooling fan(e) and shroud assembly from Ihe rear ot the radiator, as described in Section 5.
3.4a Slacken the clip and disconnect the radiator bottom hose