1998 FIAT PUNTO Exhaust

ib-4 Component location - diesel models
Underbonnet view - turbo diesel model
1 Engine oil filter
cap
2 Engine oil dipstick 3 Oil
tilter
4 Brake/clutch fluid
reservoir
5 Air cleaner
cover
6 Power steering pump 7 Coolant expansion
tank
8 Windscreen washer
fluid
reservoir 9 Front suspension strut upper mounting 10 Fuel filter/heater
housing
11
Fuel
injection pump 12 Battery 13 Power steering fluid reservoir
Front underbody view - turbo diesel model
1 Oil
fitter
2 Sump drain plug 3 Transmission drain plug 4 Electric cooling fan unit 5 Left-hand
driveshaft
6 Intermediate
shaft
7 Bight-hand
driveshaft
8 Front suspension lower arms 9 Front anti-roll
bar
10 Exhaust downpipe 11 Front brake calipers 12
Rear
engine mounting 13 Radiator bottom hose
expert22 fl/ia http://rutracker.org

Component location - diesel models ib-s
Rear underbody view - turbo diesel model
1
Fuel tank
2
Exhaust
tailpipe
and
silencer 3 Fear axle 4 Coil springs 5
Rear anti-roll bar
€
Handbrake cables
7
Rear brake pressure regulating valve
8
Rear shock
absorber
lower
mountings
Maintenance procedures
1 Introduction
This Chapter Is designed to help the home mechanic maintain his/her vehicle for safety, economy, long life and peak performance. The Chapter contains a master maintenance schedule, and Sections dealing specifically with each task in the schedule. Visual checks, adjustments, component renewal and other helpful items are included. Refer to the accompanying illustrations of the engine compartment and the underside of the vohicle for the locations of the various components. Servicing your vehicle in accordance with ihe mileage/time maintenance schedule and the following Sections will provide a planned maintenance programme, which should result in a long and reliable service life. This is a comprehensive plan, so maintaining some items but not others at the specified service internals, will not produce the same results. As you service your vehicle, you will ctecover that many of the procedures can. and should, be grouped together, because of the particular procedure being performed, or because of the proximity of two otherwise-unrelated components to one another. For example, if the vehicle is raised for any reason, the exhaust can be inspected at the same time as the suspension and steering components. The first step in this maintenance programme is to prepare yoursetf before the
actual work begins. Read through all the Sections relevant to the work to be carried out. then make a list and gather all the parts and tools required. If a problem is encountered, seek advice from a parts specialist, or a dealer service department.
2 Regular maintenance
1 If, from the time Ihe vehicle is new, the routine maintenance schedule is followed closely, and frequent checks are made of fluid levels and high-wear Items, as suggested throughout this manual, the engine wifl be kept in relatively good running condition, and the need for additional work will be minimised. 2 It is possible that there will be times when the engine is running poorly due to the lack of regular maintenance. This is even more likely if a used vehicle, which has not received regular and frequent maintenance checks, is purchased, in such cases, additions! work may need to be carried out, outside of the regular maintenance intervals. 3 If engine wear is suspected, a compression test {refer to Chapter 2C} will provide valuable information regarding the overall performance of the main internal components. Such a test can be used as a basis to decide on the extent of the work to be carried out. If, for example, a compression test indicates serious Internal engine wear, conventional maintenance as
described in this Chapter will not greatly improve the performance of the engine, and may prove a wa3te of time and money, unless extensive overhaul work Is carried out first. 4 The following series of operations are those usually required to Improve the performance of a generally poor-running engine:
Primary operations a,I Clean, Inspect and test the battery (See Weekly checks). b) Check all the engine-related fluids (See Weekly checks). c) Drain the water from the fuel filter (Section 4) d) Check the condition and tension of the auxiliary dnvebeft(s) (Section 16). e) Check the condition of the air fitter, and renew if necessary (Section 13). f) Check the condition of all hoses, and check for fluid leaks (Section 8). g) Check the engine idle speed setting {Section 11). h) Check the exhaust gas emissions (Section 25). 5 If the above operations do not prove fully effective, carry out the following secondary operations:
Secondary operations All items listed under Pnmary operations, plus the following: a) Check the charging system (Chapter 5A, Section 4). b) Renew the fuel filter (Section 12) and check the fuel system (see Chapter 4Q.

ib.6 Maintenance procedures - diesel models
Every 5000 miles (7500 km) or 6 months
3 Engine oil and filter renewal it-
1 Frequent oil and filter changes are the most important preventative maintenance procedures which can be undertaken by the OlY owner. As engine oil ages, if becomes diluted and contaminated, which leads lo premature engine wear. 2 Befote starting this procedure, gather ail the necessary tools and materials. Also make sure that you have plenty of clean rags and newspapers handy, to mop up any splits. Ideally, the engine oil should be warm, as it will drain better, and more built-up sludge will be removed with it. Take care, however, not to touch the exhaust or any other hot parts of the engine when working under the vehicle. To avoid any possibility of scalding, and to protect yourself from possible skin irritants and other harmful contaminants in used engine oils, it is advisable to wear gloves when carrying out this woik. Access to the underside of the vehicle will be greatly improved if it can be raised on a lilt, driven onto ramps, or jacked up and supported on axle stands {see Jacking and vehicle support). Whichever method Is chosen, make sure that the vehicle remains level, or If it is at an angle, that Ihe drain plug is at the lowest point. 3 Slacken the drain plug about half a turn using a 12 mm Allen key (see Illustration) Position the draining container under the drain plug, then remove the plug completely (see Haynes Hint), 4 Allow some time for the oid oil to dram, noting that it may be necessary to reposition the container as the oil (tow slows to a trickle. 5 After all the oil has drained, wipe off the drain plug wilh a clean rag, then clean the area around the drain plug opening and refit the plug. Tighten the ptug securely. 6 If the filter is also to be renewed, move the container Into position under the oil filter, which Is located on the front right-hand side of the engine. 7 Using an oil filter removal tool if necessary, slacken the filter initially, then unscrew It by hand the rest of the way (see illustrations).
3.3 Using a 12 mm Allen key to loosen the engine oil drain plug
Empty the oil In (he old filter Into Ihe container. 8 Use a clean rag to remove all oil, dirt and sludge from the filter sealing area on the engine. Check the old lilter to make sure thai the rubber sealing ring has not stuck to the engine. If it has. carefully removo it. 9 Apply a light coating of clean engine oil to the sealing ring on the new filter, then screw it into position on the engine. Tighten the filter firmly by hand only • do not use any tools (see Illustration), 10 Remove Ihe old oil and all tools from under the vehicle then lower Ihe vehicle to the ground (If applicable). 11 Remove tho dipstick, then unscrew (he oil liiler cap from the cylinder head cover. Fill the engine, using Ihe correct grade and typo of oil (see Weekly checks). An oil can spout or funnel may help to reduce spillage Pour in half the specified quantity of oil first, then wait a few minutes for the oil to fall to the sump. Continue adding oil a smalt quantity at a time until Ihe level Is up to the MAX mark on the dipstick. Refit the filler cap. 12 Start the engine and run it for a tew minutes; check for leaks around the oil filter seal and the sump drain plug. Note that there may be a delay of a few seconds before the oil pressure warning light goes oul when the engine is first started, as the oil circulates through the engine oil galleries and the new oil filter before the pressure builds up.
Keep the drain plug pressed Into the sump while unscrewing It by hand the lost couple of turns. As the plug releases, move It away sharpty so that the stream of oil issuing from the sump runs Into the container, not up your sieeve.
13 Switoh off the engine, and wait a few minutes for Ihe oil to settle in the sump once mora. With the new oil circulated and the fitter completely full, recheck the level on Ihe dipstick, and add more oil as necessary. 14 Dispose ot the used engine oil safely, wilh reference lo General repair pioceduros In Ihe reference Sections of this manual.
4 Fuel filter water draining ^
1 A water drain screw is provided at the base of the fuel filter. 2 Position a suitable container under ihe fuel filter, Loosen Ihe bleed screw on the lop ol the filter, and open the drain screw at the base of tne filter by turning it anti-clockwise Allow fuel and water to drain until fuel, free from water, emerges from tho drain screw outlet. Close tne drain and bleed screws and tighten them securely 3 Dispose of the drained fuel safely. 4 Start tho onglno. II difficulty is experienced, Weed the fuel system (see Chapter 4C).
3.7a Using an oil fitter removal chain strap 3.7b Removing the oil filter 3.9 Now oil filter tightened by hand

ib-8 Every 10 000 miles - diesel models
10.1 Checking the condition of a driveshaft gaiter
9 Exhaust system check
1 With the engine cold {at least an hour after tho vehicle has been driven), check ihe complete exhaust system from the engine to the end of the tailpipe. The exhaust system Is most easily checked with the vehicle raised on a hoist, or suitably supported on axle stands (see Jacking and vehicle support), so that the exhaust components are readily visible and accessible. 2 Check the exhaust pipes and connections for evidence of leaks, severe oorrosion and damage. Make sure that all brackets and mountings are In good condition, and that all relevant nuts and bolts are tight, Leakage at any of the joints or in other parts of tho system will usually show up as a black sooty stain in the vicinity ot the leak. 3 Rattles and other noises can often be Iracod to the exhaust system, especially the brackets and mountings. Try to move the pipes and silencers. If the components are able to come into contact with the body or
suspension parts, secure the system with new mountings. Otherwise separate the joints (if possible) and twist the pipes as necessary to provide additional clearance.
10 Driveshaft gaiter check
I
1 With the vehicle raised and securely supported on stands (see Jacking and vehicle support), turn the steering onto lull lock, then slowly rotate the roadwheel. Inspect the condition ol the outer constant velocity (CV) joint rubber gaiters, squeezing the gaiters to open out the folds. Check for signs ot cracking, splits or detenoration of the rubber, which may allow the grease to escape, and lead to water and grit entry into the joint. Also check the security and condition of the retaining clips. Repeat these checks on the Inner CV joints (see illustration). If any damage or deterioration is found, the gaiters should be renewed (see Chapter 8. Section 3). 2 At the same time, check the general condition of the CV joints themselves by first holding the driveshaft and attempting to rotate the wheel. Repeat this check by holding the inner joint and attempting to rotate the driveshaft. Any appreciable movement indicates wear in the joints, wear in Ihe driveshaft splines, or a loose driveshaft retaining nut.
11 Idle speed check and adjustment
1 The usual type of tachometer (rev counter), which works from ignition system pulses, cannot be used on diesel engines. A
diagnostic socket is provided for the use of Flat test equipment, but this will not normally be available to the home mechanic. If it Is not felt that adjusting the Idle speed by ear 19 satisfactory, It will be necessary to purchase or hire an appropriate tachometer, or else leave tho task to a Fiat dealer or other suitably equipped specialist, 2 Before making adjustments, warm up the engine to normal operating temperature. Make sure that the accelerator cable is correctly adjusted (see Chapter 4C). 3 The adjustment must be made with all electrical components (Including the cooling fan) switched off. It the fan comes on dunng the adjustment, wait until it switches off automatically before proceeding. 4 The idle adjustment screw Is located on the top of the fuel injection pump (see illustration). To adjust the idie speed loosen the locknut and turn the screw as required then tighten the locknut. 5 On completion switch off the engine.
12 Fuel filter renewal i
1 The fuel filter is located on the bulkhead in the engine compartment. An electrically-operated heater is located between the filter and tlw housing, 2 Position a suitable container under the fuel filler. Loosen tho bleed screw on the top of the filter, then disconnect the wiring from Ihe water sensor and loosen the water drain screw on the bottom of the filter. Allow the fuel to drain completely (see illustration). 3 Tighten the drain and bleed screws, then Use an oii niter strep to loosen the fuel filter {see illustration).
12.2 Loosening the bleed screw on the top of the fuel filter
11.4 fdie speed adjustment 1 Locknut 2 Adjustment screw

Every 20 000 miles - diesel models ib.h
18
Valve clearance check and
adjustment
1 The Importance of having the valve clearances correctly adjusted cannot be Distressed, as they vitally affect the performance of the engine. Adjustment should only be necessary when the valve gear nas become noisy, after engine overhaul, or when trying to trace the cause of power loss. The clearances are checked as follows. The engine must be cold for the check to be ttcurate. 2 Apply the handbrake then jack up the right-hand front of the vehicle and support on an axle stand (see Jacking and vehicle support). Engage 4th gear. The engine can now be rotated by turning the right-hand front roadwfteei. 3 Remove ail four glove plugs as described In Chapter 5C. 4 Remove the air cleaner cover and air duct
then
remove the camshaft cover as described
in
Chapter 2C. 6 Each valve clearance must be checked wnen the high point of the cam is pointing directly upward away from the cam follower. 6 Check the clearances in the firing order 1-3-4-2, No 1 cylinder being at the timing belt end of the engine. This will minimise the amount of crankshaft rotation required. 7 Insert the appropriate feeler blade between
the heel
of the cam and the cam follower shim of the First valve (see Illustration). If necessary alter the thickness of the feeler blade until it is a stiff, sliding fit. Record the thickness, which will, of course, represent the
vafve
clearance tor Ihis particular valve. 8 Turn the engine, check the second valve devance and record it. t Repeat the operations on all the remaining valves. recording their respective clearances. 10 Remember that the clearance for inlet and exhaust valves differs - see Specifications. Counting from the timing cover end of the
engine,
the valve sequence is: Wef 2-4-5-7 Etfiat/sf 7-3-6-8
11 Where clearances are incorrect the particular shim will have to be changed. To remove the shim, turn the crankshaft until the high point of the cam is pointing directly upward. The cam follower will now have to bo depressed so that the shim can be extracted. Special tools are available from your Fiat dealer to do the job. otherwise you will have to make up a forked lever to locate on the rim of ihe cam follower. This must allow room for the shim to be prised out by means of the cut-outs provided in the cam follower rim (see illustration). 12 Once Ihe shim is extracted, establish Its thickness and change it for a thicker or thinner one to bring the previously recorded clear-ance within specification, For example, if the measured valve clearance was 1.27 mm too great, a shim thicker by this amount will be required. Conversely, if the clearance was 1.27 mm too small, a shim thinner by this amount will be required. 13 Shims have their thickness (mm) engraved on ihem; although the engraved side should be fitted so as not to be visible, wear still occurs and often obliterates the number. In this case, measuring their thickness with a metric micrometer is the only method to establish their thickness (see illustration). 14 In practice, if several shims have to be changed, they can often be interchanged, so avoiding the necessity of having to buy more new shims than is necessary. 15 If more than two or three valve clearances are found to be incorrect, it will be more convenient to remove the camshaft lor easier removal of the shims. 16 Where no clearance can be measured, even with the Ihinnest available shim in position, the valve will have to be removed and the end of its stem ground off squarely. This will reduce its overall length by the minimum amount to provide a clearance. This job should be entrusted to your dealer as it is important to keep the end of the valve stem square. 17 On completion, refit the camshaft cover and gasket, air cleaner and duct, and glosvplugs. 18 Lower the vehicle to the ground.
19 Hinge and lock lubrication
I
1 Lubricate the hinges of the bonnet, doors and tailgate with a light general-purpose oil. Similarly, lubricate all latches, locks and lock stnkers. At the same time, check the security and operation of all the locks, adjusting them if necessary (see Chapter 11). 2 Lightly lubricate the bonnet release mechanism and cable with a suitable grease.
20 Headlight beam adjustment
I
1 Accurate adjustment of the headlight beam Is only possible using optical beam-setting equipment, and this work should therefore be carried out by a Fiat dealer or service station with the necessary facilities. In an emergency, however, the following procedure will provide an acceptable light pattern. 2 Position the car on a level surface with tyres correctly inflated, approximately 10 metres in front of, and at right-angles to, a wall or garage door. 3 Draw a horizontal tine on the wall or door at headlamp centre height. Draw a vertical line corresponding to the centre line of the car. then measure off a point either side of this, on the horizontal line, corresponding with the headlamp centres. 4 Switch on the main beam and check that the areas of maximum Illumination coincide with the headlamp centre marks on the wall. If not, turn the adjustment screw located on the upper Inside edge of the headlight unit to adjust the beam laterally, and the adjustment screw located on the upper outside edge of the headlight unit to adjust the beam vertically. On models with electric headlight adjustment, make sure that it Is set at its basic setting before making the adjustment,

1B«12 Every 20 000 miles - diesel models
21 Road test
Instruments and electrical equipment 1 Check the operation of atl instruments and electrical equipment. 2 Make sure that all instruments read correctly, and switch on all electrical equipment rn turn, to check that It functions properly. Steering and suspension 3 Check for any abnormalities in the steering, suspension, handling or road feel. 4 Drive the vehicle, and check that there are no unusual vibrations or noises. 5 Check that the steering feete positive, with no excessive sloppiness, or roughness, and check for any suspension noises when cornering and driving over bumps. Drivetrain 6 Check (he performance of the engine, clutch, transmission and driveshafts.
7 Listen for any unusual noises from the engine, clutch and transmission. 8 Make sure that the engine runs smoothly when Idling, and that there is no hesitation when accelerating. 9 Check that the clutch action is smooth and progressive, that tho drive is taken up smoothly, and that the pedal travel Is not excessive. Also listen for any noises when the clutch pedal is depressed. 10 Check that all gears can be engaged smoothly without noise, and that the gear lever action Is not abnormally vague or notchy. 11 Listen for a metallic clicking sound from ihe front of the vehicle, as the vehicle « driven slowly In a circle with the steering on full-lock. Carry out this check In both directions, if a clicking noise is heard, this Indicates wear in a driveshaft |oinl, in which case renew the joint if necessary.
Check the braking system 12 Make sure that the vehicle does not pull to one side when braking, and that the wheels do not lock prematurely when braking hard.
13 Check that there Is no vibration through the steering when braking. 14 Check that the handbrake operates correctiy without excessive movement of th« lever, end that it holds the vehicle stationery on a slope. 15 Test the operation of the brake servo unit as follows. With the engine off, depress the footbrake four or five times to exhaust the vacuum. Hold the brake pedal depressed, then start the engine. As the engine starts, there should be a noticeable give In the brake pedal as vacuum builds up. Allow the engine to run for at least two minutes, and then switch it off. If the brake pedal is depressed now, it should be possible to detect a hiss from the servo es the pedal is depressed. After about four or five applications, no fimher hissing should be heard, and the pedal should feel considerably harder. Note: The vacuum for the servo unit is provided by the vacuum pump mounted on the left-hand end of t/ie cylinder head.
Every 30 000 miles (45 000 km) or 3 years
22 Manual transmission oil level check ;5§
1 Park the vehicle on a level surface. If possible over an inspection pit or on a ramp as the filler/level plug is best reached from under Ihe engine compartment. The oil level must be checked before the car Is driven, or at least 5 minutes after the engine has been switched off. If the oil is checked Immediately after driving the car. some of the oil will remain distnbuted around the transmission compo-nents, resulting In an inaccurate level reading. 2 Wipe clean the area around the filler/level plug, which is situated on tho front of the
transmission (see illustration). Using an Allen key. unscrew the plug and clean it. 3 The oil level should reach the lower edge of the filler/level hole. A certain amount of oil will have gathered behind the filler/level plug, and will trickle out when it is removed; this does not necessarily Indicate that the level Is correct. To ensure that a true level Is established, wait until the Initial trickle has stopped, then add oil as necessary until a trickle of new oil can be seen emerging. The level will be correct when the flow ceases; use only good-quality oil of the specified type-Make sure that the vehicle Is completely level when checking the level and do not overfill. 4 When the level is correct refit and tighten the plug and wipe away any spilt oil.
22.2 Transmission filler/level plug location
Every 40 000 miles (60 000 km) or 4 years
23 Rear brake shoe check
1 Chock the front wheels then jack up the rear of the car and support It on axle stands (see Jacking and Vehicle Support), Remove the rear roadwhecla. 2 Using the inspection hole at the edge ot the brake drum, check that the linings are not worn below the minimum thickness given In the Spec ifi cat Ions (see Illustration). If necessary use a torch. 3 If the friction material on any shoe is worn down to the specified minimum thickness or iess. all four shoes must be renewed as a set, 4 At the same time check for signs of brake fluid leakage. 5 For a comprehensive check, the brake
drum should be removed and cleaned. This will allow the wheel cylinders to be checked, and the condition of the brake drum itself to be fully examined (see Chapter 9). 8 Refit the rubber plugs then lower the car to the ground.
24 Timing belt renewal
Refer to Chapter 2C. Note: Although the normal interval for timing belt
ranees/a!
is 70 000
mHes
(105 000
km),
it is strong recommended that the interval is reduced on vehicles which are subjected to intensive use, ie, mainly short journeys or a lot of stop-start driving. The actual belt renewal interval is therefore very much up to tho individual owner.
That being said, it is highly recommended to err on the side of safety, and renew (he belt at
this
earlier interval, bearing in mind the drastic consequences resulting from belt fetfure.
23.2 Check the thickness of the shoe friction material through the hole on the edge of the drum (arrowed)

2A*10 SOHC (8-valve) petrol engine in-car repair procedures
Torque wrench settings Nm
IM
ft Camshaft cover 8 6 Camshaft sprocket 70 52 Cylinder head; Stage 1 30 22 Stage 2 Angle-lighten a further 90° Siege 3 Angle-tighten a further 90B Crankshaft sprocket centre bott 100 74 Engine mounting bolt: M10X1.25 69 44 MB 25 18 Engine mounting nut (M10x 1.25) 60 44 Flywheet/driveplate 44 32 Sump 10 7 Timing belt tensJoner 28 21
1 General information
Using this Chapter Chapter 2 is divided Into four Parts: A. 8. C and D. Repair operations that can be carried out with the engine in the vehicle are described in Part A. SOHC (8-valve) petrol engines, Part B. DOHC (18-valve) petrol engines and Part C, diesel engines. Part 0 covers the removal of the engine/transmission as a unit, and describes the engine dismantling and overhaul procedures. In Parts A, 9 and C, the assumption Is made lhat the engine is Installed in the vehicle, with sll ancillaries connected. If the engine has been removed for overhaul, the preliminary dismantling Information which precedes each operation may be ignored.
Engine description Throughout this Chapter, engines are identified by their capacities. A listing of all engines covered, together with their code letters, is given in the Specifications. The engines covered In this Part of Chapter 2 are water-cooled, single overhead camshaft, in-line four-cylinder units, with cast Iron cylinder Mocks and aluminium-alloy cylinder heads. All are mounted transversely at the front ot the vehicle, with the transmission bolted to the left-hand side of the engine, The cylinder head carries the camshaft which is driven by a toothed timing belt and runs In three bearings. It also houses the inlet and exhaust valves, which are closed by single coil springs, and which run in guides pressed Into the cylinder head. The camshaft actuates the vatves directly via cam followers mounted in the cylinder head. Adjustment of the valve clearances is by means of shims located on top of the followers. The cylinder head contains Integral oitways which supply and lubricate the tappets. The crankshafl Is supported by five main bearings, and endftoat is controlled by a thrust bearing fitted to the upper section of the centre main bearing.
Engine coolant is circulated by 8 pump, driven by the timing belt. For details of the cooling system, refer to Chapter 3. Lubricant is circulated under pressure by a pump, driven from ihe front of the crankshaft. Oil Is drawn from the sump through a strainer, and then forced through an externally-mounted, replaceable screw-on filter. From there, It is distributed to the cylinder head, where It lubricates the camshaft journals and tappets, and also to the crankcase, where il lubricates the main bearings, connecting rod big and smell-ends, gudgeon pins and cylinder bores. On 1242 cc engines, oil jets are fitted lo the base of each cylinder bore -these spray oil onto the underside of the pistons, to Improve cooling.
Repair operations possible with the engine in the car The following work can be carried out with the engine in the car a) Compression pressure - testing b) Auxiliary drivebelt - removal and refitting (refer to Chapter 1A) c) Vatve clearances - checking and adjustment (refer to Chapter I A) d) Camshaft cover - removal and refitting e) Timing belt and covens - removal and refitting f) Timing belt tensioner and sprockets -removal and refitting g) Cylinder head - removal and refitting' h) Camshaft and cam followers • removal and refitting' t) Camshaft oil seal - renews/ j) Crankshaft oil seals - renewal k) Flywheel/dnvepfate • removal, inspection and refitting l) Engine mountings - inspection and renewal m)Sump - removal and refitting n) Oil pump and pick-up tube assembly
•
removai. inspection and refitting *Cylinder head dismantling procedures are detailed In Chapter SO, with details of camshaft and cam follower removal. Note: It is possible to remove the pistons and connecting rods (after removing the cylinder head and sump) without removing the engine. However, this is not recommended. Work of
this nature is more easily and thoroughly completed with the engine on the bench, as described In Chapter 2D.
2 Location of
TDC
on % No
1
cylinder
General Information 1 The camshaft Is driven by the crankshaft, by means of sprockets and a timing belt. Both sprockets rotate In phase with each other and this provides the correct valve timing as the engine rotates. When (he liming belt is removed during servioing or repair, it Is possible for the camshaft and crankshaft to rotate Independently of each other and the correct valve timing Is then lost. 2 The design of the engines covered In this Chapter are such lhat potentially damaging piston-to-valve contact may occur if the camshaft is rotated when any of the pistons are stationary at, or near, the top of their stroke. 3 For this reason it is important lhat Ihe correct phasing between the camshaft and crankshaft is preserved whilst the timing belt Is off the engine. This is achieved by setting the engine In a reference position (known as Top Dead Centre or TDC) before the timing belt Is removed and then preventing the camshaft and crankshaft from rotating until the belt is refitted. Similarly, if ths engine has been dismantled for overhaul, the engine can be set to TOC during reassembly to ensure that Ihe correct shaft phasing is restored. 4 TDC is the highest point In the cylinder that each piston reaches as the crankshaft turns. Each piston reaches TDC at Ihe end of the compression stroke and again at the end of the exhaust stroke. However, for the purpose of timing the ongine. TDC refers to the position of No 1 piston at the end of Its compression stroke. On ail engines In this manual, No 1 piston (and cylinder) Is at the timing belt end of the engine. 5 The camshaft sprocket Is equipped with a marking which, when aligned with a reference marking on the cylinder head, indicates that the camshaft is correctly positioned for cyl-inder No 1 al TDC on its compression stroke.

2A*10 SOHC (8-valve) petrol engine in-car repair procedures
2.11 Unscrewing the crankshaft pulley bolts
6 Itae crankshaft sprocket Is also equipped •nth a timing mark - when this is aligned with 3relarence marking on the oil pump cover.
Hie
engine is set with cylinders No 1 and 4 at
TDC.
Note that it is the camshaft positioning that determines whether a cylinder is on its comcression or exhaust stroke.

Location
of TDC on cylinder No 1 7 Remove the air cleaner and ducting as descnbed in Chapter 4A or 4B. Remove the
spark
plug from No 1 cylinder as described in Chapter 1A. 8 Firmly apply the handbrake, then |ack up
the
front of the car and support it securely on iiia stands (see Jacking end vehicle support). 9 Remove the auxiliary drivebelt(s) as described in Chapter 1A. 10 Unbolt and remove the timing belt cover. Mole the bolt located at the bottom of the
coven
this can be easily overlooked. 11 Undo the three bolts and remove the crankshaft pulley from the sprocket (see {lustration). 12 Turn Ihe engine in its normal direction of rotation (using a socket or spanner on Ihe crankshaft sprocket centre bolt) until pressure an be felt at No
1
cylinder spark plug hole.
1 flfliyflg^ Remove all four spark plugs; "••"•1 this will make the engine HlNTl easier to turn; refer to Chapter 1A for details.
13 Continue turning the engine until the crahaft sprocket TDC timing mark is aligned with the mark on the cylinder head and the crankshaft sprocket timing mark is aligned with the mark on the oil pump cover (see ilustrations). 14 The engine is now set at TDC for No 1 cylinder on compression.
3 Cylinder compression test t ^
1 When engine performance Is down, or if misfiring occurs which cannot be attributed to tne ignition or fuei systems, a compression isst can provide diagnostic clues as to the
2.13a Camshaft sprocket and cylinder head TDC timing marks (arrowed) aligned -shown with timing belt removed engine's condition. II the test is performed regularly, it can give warning of trouble any other symptoms become apparent. 2 The engine must be fully warmed-up to normal operating temperature, the battery must be fufly charged, and all the spark plugs must be removed (Chapter 1A). The aid of an assistant will also be required. 3 Disable the ignition system by dis-connecting the LT wiring plug to the ignition coils. 4 Fit a compression tester to the No 1 cyl-inder spark plug hole - the type of tester which screws into the plug thread is to be preferred, 5 Have the assistant hold the throttle wide open, and crank the engine on the starter motor; after one or two revolutions, the compression pressure should build up to a maximum figure, and then stabilise. Record the highest reading obtained. 6 Repeat the lest on the remaining cylinders, recording the pressure in each. 7 All cylinders should produce very similar pressures; any excessive difference 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 head could also be the cause). 8 If the pressure in any cylinder is very low. carry out the following test to isolate the cause. Introduce a teaspoonful of clean oil into that cylinder through its spark plug hole and repeat the test. 9 If the addition of oil temporarily improves the compression pressure, this indicates that bore or piston wear Is responsible for the pressure loss. No improvement suggests that leaking or burnt valves, or a biown head gasket, may be to blame. 10 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. 11 If one cylinder is about 20 percent lower
2.13b Crankshaft sprocket and oil pump cover TDC timing marks (arrowed) aligned
than the others and Ihe engine has a slightly rough idle, a worn camshaft lobe could be the cause. 12 On completion of the test, refit the spark plugs and reconnect the ignition LT wiring plug.
4 Timing belt and covers -removal and refitting ^
Note: Fiat specify the use of a special timing belt fens/on measuring toot to correctly set tho timing belt tension. If access to this equipment cannot be obtained, an approximate setting can be achieved using the method described below. It 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 tension is known fo be correct. Refer to a Fiat dealer foradvSce.
General information 1 The function of the timing belt is to drive Ihe camshaft and coolant pump. Should the belt slip or break In service, the valve timing will be disturbed and piston-to-valvo contact will occur, resulting in serious engine damage, 2 The timing belt should be renewed ai the specified intervals (see Chapter 1A), or earlier if it is contaminated with oil. or if it is at all noisy in operation (a scraping noise due to uneven wear). 3 If the timing belt is being removed, it Is a wise precaution to check the condition of the coolant pump at the same time (check for signs of coolant leakage). This may avoid the need to remove the timing belt again at a later stage, should the coolant pump fall.
Removal 4 Firmly apply the handbrake, then jack up the front of the car and support it securely on axle stands (see Jacking and vehicle support). Remove the right-hand front road wheel. 5 Remove the air cleaner and air ducting as described in Chapter 4A or 46. 6 Remove the auxiliary drivebelt(s) and the spark plugs as described in Chapter 1A.
2A