Preheating system - diesel models FIAT PUNTO 1995 176 / 1.G Workshop Manual

Contents
REPAIRS AND OVERHAUL
Engine and associated systems SOHC (8-valve) petrol engine in-car repair procedures Page 2A«1 DOHC (16-valve) petrol engine in-car repair procedures Page 2B«1 Diesel engine in-car repair procedures Page 2C«1 Engine removal and overhaul procedures Page 2D«1 Cooling, heating and ventilation systems Page 3»1 Fuel system - single-point petrol injection models Page 4A«1 Fuel system - multi-point petrol injection models Page 4B«1 Fuel system - diesel models Page 4C»1 Exhaust and emission control systems Page 4D*1 Starting and charging systems Page SA«1 Ignition system - petrol models Page SB«1 Preheating system - diesel models Page 5C>1
Transmission Clutch Page 6»1 Manual transmission Page 7A«1 Automatic transmission Page 7B*1 Driveshafts Page 8*1
Brakes and suspension Braking system Page 9*1 Suspension and steering Page 10-1
Body equipment Bodywork, trim and Fittings Page 11«1 Body electrical systems Page 12*1
Wiring diagrams Page 12»13
REFERENCE
Dimensions and weights Page REF«1 Conversion factors Page REF*2 Buying spare parts Page REF»3 Vehicle identification Page REF«3 General repair procedures Page REF«4 Jacking and vehicle support Page REF»5 Disconnecting the battery Page REF«5 Tools and working facilities Page REF-6 MOT test checks Page REF»8 Fault finding Page REF»12 Glossary of technical terms Page REF»20
index Page REF»24
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2D*10 Engine removal and overhaul procedures
12.18 Angle-tightening the main bearing cap bolts (petrol engine)
12.Ida Application area for silicone Instant gasket on crankshaft rear oil seal housing (petrol engine) 12.19b Refitting the crankshaft rear oil seal housing (petrol engine)
19 Fit a new oil seal to the crankshaft rear oil seal housing. Apply grease to the seal lips. On 1108 cc petrol engines a conventional gasket Is not used at the oil seal retainer joint face, but a 3 mm diameter bead of RTV (Instant) silicone gasket must be applied as shown -allow at least one hour 1or the gasket to cure before oil contacts it. On all other engines a gasket Is fitted Securely tighten the housing bolts (see Illustrations). 20 Check that Ihe crankshaft rotates freely by turning It by hand. If resistance Is fell, re-check the running clearances, as described above. 21 Carry out a check of the crankshaft endfloat as described at the beginning of Section 8. If the thrust surfaces of the crankshaft have been checked and new thrust washers hove been fitted, then the endfioat should be within specification.
22 Refit the pistons and connecting rods as described in Section 7. 23 Refit the flywheeVdriveplate, and-vibration plate (16-valvo engines), oil pump and pick-up tube, and sump with reference to the relevant Sections of Parts A, B or C of this Chapter.
13 Engine -initial start-up after overhaul and reassembly
1 With the engine refitted In the vehicle, double-check the engine oil and coolant levels. Make a final check that everything has been reconnected, and that there are no tools or rags left In the engine compartment.
Petrol engine models 2 Remove the spark plugs, then disable the
ignition system by disconnecting the LT wiring plug to the ignition colls. 3 Turn the engine on the starter until Ihe oi pressure warning light goes out. Refit ihe spark plugs, and reconnect the LT wiring.
Diesel engine models 4 Disconnect tho wiring from the stop solenoid on the Injection pump, then turn the engine on the starter motor until the oil pressure warning light goes out. Reconnect ihe wire to the stop solenoid. 6 Fully depress the accelerator pedal, turn tho ignition key to its first position and wait tor HHJ preheating warning light to go out.
All models 6 Start the engine, noting that this may take i little longer than usual, due to the fuel system components having been disturbed.
12.19c On diesel engines use a screwdriver to prise out the rear oil seal 12.19d Locate the new oil soalln the housing (diosel engine)... 12.19e ... and use a block of wood to drive it in
12.19f On Diesel engines fit the gasket to the cylinder block ... 12.19g ... then locate the rear oli seal housing... 12.19h ... and Insert the bolts

5A«2 Starting and charging systems
1 General information and precautions
General information The engine electrical system consists mainly of the charging and starting systems. Because of their engine-related functions, these components are covered separately from the body electrical devices such as the Ilght3, Instalments, etc (which are covered In Chapter 12). On petrol engine models refer to Part B for information on the ignition system, and on diesel models refer to Part C for information on the preheating system. The electncal system Is of 12-volt negative earth type. The battery fitted as original equipment is of maintenance* free (sealed for life} type and Is charged by the alternator, which is belt-driven from the crankshaft pulley. If a non-original battery is fitted It may be of standard or low maintenance type. The starter motor is of the pre-engaged type Incorporating an integral solenoid. On starting, the solenoid moves the drive pinion into engagement with the flywheel ring gear before the starter motor is energised. Once the engine has started, a one-way clutch prevents the motor armature being driven by the engine until the pinion disengages from the flywheel.
Precautions Further details of the various systems are given In the relevant Sections of this Chapter. While some repair procedures are given, the usual course of action is to renew the component concerned. The owner whose interest extends beyond mere component renewal should obtain a copy of the Automobile Electrical & Electronic Systems Manual, available from the publishers of this manual It Is necessary to take extra care when working on the electrical system to avoid damage to semiconductor devices (diodes and transistors), and to avoid the risk of personal injury. In addition to the precautions given in Safety first! at the beginning of this manual, observe the following when working on the system: Always remove rings, watches, etc before working on the electrical system. Even with the battery disconnected, capacitlve discharge could occur If a component's live terminal is earthed through a metal object. This could cause a shock or nasty bum. Do not reverse the battery connections. Components such as the alternator, electronic control units, or any other components having semi-conductor circuitry could be irreparably damaged. If the engine is being started using jump leads and a slave battery, connect the batteries positive-to-posibve and negative-to-
negative (see Jump starting). This also applies when connecting a battery charger but In this case both of the battery terminals should first be disconnected. Never disconnect the battery terminals, the alternator, any electrical wiring or any test Instalments when the engine Is running. Do not allow the engine to turn the alter-nator when the alternator Is not connected. Never test for alternator output by flashing the output lead to earth. Never use an ohmmeter ot the type Incorporating a hand-cranked generator for circuit or continuity testing. Always ensure that the battery negative lead is disconnected when working on the electrical system. Before using electric-arc welding equipment on the car, disconnect the battery, alternator and components such as the fuel Injection/ignition electronic control unit to protect them from the risk of damage. Several systems fitted to the vehicle require battery power to be available at all times, either to ensure their continued operation (such as the clock) or to maintain control unit memories or security codos which would be wiped if the battery were to be disconnected. To ensure that there are no unforeseen consequences of this action. Refer to Disconnecting the battery In the Reference Section of this manual for further Information.
2 Battery- % testing and charging
Standard and tow maintenance battery - testing 1 If the vehicle covers a small annual mileage, it is worthwhile checking the specific gravity of the electrolyte every three months to determine the state of charge of the battery. Use a hydrometer to make the check and compare the results with the following table, Note that the specific gravity readings assume an electrolyte temperature of 15*C (60'F); for every 10*C (18°f) below 158C (60aF) subtract 0.007, For every 108C (16'F) above 15"C (60'F) add 0.007. Ambient temperature Above 26"C Below 25DC Charged 1,210 to 1£30 1,270 to 1.290 70% charged 1.170to1.l90 1.230to1.250 Discharged 1.050toJ.070 1.110 to 1.130 2 If the battery condition is suspect, first check the specific gravity of electrolyte In each cell. A variation of 0.040 or more between any cells indicates loss of electrolyte or deterioration of the internal plates. 3 If the specific gravity variation is 0.040 or more, the battery should be renewed. If the cell variation Is satisfactory but the battery is discharged, it should be charged as described later in this Section.
Maintenance-free battery -testing 4 In cases where a sealed tor life maintenance-free battery is fitted, topplng-up and testing of the electrolyte in each cell Is not possible. The condition of the battery can therefore only be tested using a battery condition Indicator or a voltmeter. 5 Certain models may be fitted with a maintenance-free battery with a built-in charge condition Indicator. The indicator Is located in the top of the battery casing, and indicates the condition of the battery from its colour. If the Indicator shows green, then the battery is In a good state of charge. If the Indicator turns darker, eventually to black, then the battery requires charging, as described later in this Section. If Ihe indicator shows clear/yellow, then the electrolyte level in Ihe battery is too low to allow further use, and tho battery should be renewed. Do not attempt to charge, load or Jump start a battery when the indicator shows dear/yellow. 6 If testing the battery using a voltmeter, connect the voltmeter across the battery and compare the result with those given In the Specifications under 'charge condition'. The test is only accurate if the battery has not been subjected to any kind of charge for the previous six hours. If this is not the esse, switch on the headlights for 30 seconds, then wait four to five minutes baforo testing the battery after switching off the headlights. All other electrical circuits must be switched off, so check that the doors and tailgate are fully shut when making the test, 7 It the voltage reading Is less than 12.2 voHs, then the battery Is discharged, whilst a reading of 12.2 to 12.4 volts indicates 8 partially discharged condition. 6 If the battery Is to be charged, remove It from the vehicle (Section 3) and charge it as described later In this Section.
Standard and low maintenance battery - charging Note: The following is Intended as a guide only. Always refer to the manufacturer's recommendations (often printed on a label attached to the battery) before charging a battery. 9 Charge the battery at a rate of 3.5 to 4 amps and continue to charge the battery at this rate until no further rise In specific gravity Is noted over a four hour period. 10 Alternatively, a trickle charger charging at the rate of 1.5 amps can safely be used overnight. 11 Specially rapid boost charges which are claimed to restore the power of the battery in t to 2 hours are not recommended, as they can cause serious damage to the battery plates through overheating, 12 While charging the battery, note that the temperature of the electrolyte should never exceed 37.8*C(100°F),

501
Chapter 5 PartC:
Preheating system - diesel models
Contents
Glow plugs - removal, inspection and refitting 2 Preheating system - description and testing 1 Preheating system control unit - removal and refitting 3
Degrees of difficulty

Ea3y, suitable
for &
novice with little
|| experience ^

Fairty easy,
suitable for beginner with
some experience
jQ
Fairty diffctit, ^
suitable
for competent
DIY
mechanic

Difficult, suitable for
experienced DIY JR mechanic ^
Very difficult, ^ suitable fbrexpertDfY JR or professional ^
Specifications
Torque wrench setting Nm ibf ft Heater glow plugs 15 11
1 Preheating system -description and testing
Description 1 Each swirl chamber has a heater plug (commonly called a glow plug) screwed into it. The plugs are electrically-operated before and during start-up when the engine is cold. 2 Electrical feed to the glow plugs Is controlled by a relay/timer unit. The coolant temperature determines the period of heating that takes place. 3 A warning light in the instnjment panel tells the driver that preheating is taking place. When the light goes out, the engine is ready to be started. The voltags supply to the glow plugs continues for several seconds after the light goes out, If no attempt is made to start, the timer then cuts off the supply, In order to avoid draining the battery and overheating the glow plugs.
Testing 4 If the system malfunctions, testing is ultimately by substitution of known good units, but some preliminary checks may be made as follows. 5 Connect a voltmeter or 12-volt test lamp between the glow plug supply cable and earth (engine or vehicle metal). Make sure that the live connection is kept clear of the engine and bodywork. 6 Have an assistant switch on the ignition, and check that vottage is applied to the glow plugs. Note the time for which the warning light Is lit. and the total time for which voltage Is applied before the system cuts out. Switch off the ignition. 7 At an under-bonnet temperature of 20°C. typical times noted should be 5 or 6 seconds for warning light operation, followed by a further 10 seconds supply after the light goes out. Warning light time will increase with lower temperatures and decrease with higher temp-eratures.
8 If there Is no supply at all, the relay or associated winng is at fault. 9 To locate a defective glow plug, disconnect the main supply cable and the interconnecting strap from the top of the glow plugs. Be careful not to drop the nuts and washers. 10 Use a continuity tester, or a 12-voH test lamp connected to the battery positive terminal, to check for continuity between each glow plug terminal and earth. The resistance of a glow plug in good condition is very low (less than 1 ohm), so if the test lamp does not light or the continuity tester shows a high resistance, the glow plug is certainly defective. 11 If an ammeter is available, the current draw of each glow plug can be checked. After an initial surge of 15 to 20 amps, each plug should draw approximately 12 amps. Any plug which draws much more or less than this is probably defective. 12 As a final check, the glow plugs can be removed and Inspected as described in the following Section.

5C«2 Preheating system - diesel models
2.3 No 4 glow plug showing the main supply lead end the interconnecting strap 2.5 Removing a glow plug
2 Glow plugs -removal, Inspection and refitting
Removal Caution: If the preheating system has just been energised, or If tho engine has been running, the glow plugs will be very hot
1 Disconnect the battery negative terminal (refer to Disconnecting the battery in the Reference Section of this manual), 2 Remove Ihe air Inlet ducting from the front of the engine with reference to Chapter 4C, Section 2. 3 Unscrew the nut from the relevant glow plug lerminai(s). and recover the washer(s). Note that tho main supply cable is connected to Number 4 cylinder glow plug and an interconnecting strap lis fitted between the four plugs (see Illustration). 4 Where applicable, carefully move any obstructing pipes or wires lo one side to enable access to the relevant glow plug(s). 5 Unscrew the glow plug(s) and remove from the cylinder head (see illustration).
Inspection 8 Inspect each glow plug for physical damage. Burnt or eroded glow plug tips can bo caused by a bad Injector spray pattern. Have the Injectors checked if this sort of damage is found. 7 If Ihe glow plugs are In good physical condition, check them electrically using a 12 volt test lamp or continuity tester as described in the previous Section. 8 The glow plugs can be energised by applying 12 volts to them to verity that they heat up evenly and In the required time. Observe the following precautions. a) Support the glow plug by clamping it carefully in a vice or selNocking pliers. Remember it will become red-hot. b) Make sura that the power supply or test lead incorporates a fuse or overload trip to protect against damage from a short-circuit. c) After testing, allow the glow plug to cool for several minutes before attempting to handle it. 9 A glow plug In good condition will start to glow red at the tip after drawing current for 5 seconds or so. Any plug which takes much longer to start glowing, or which starts
glowing in the middle instead of at the lip, « defective. Refitting 10 Refit by reversing the removal operations. Apply a smear of copper-based anti-seize compound to the plug threads and tighten Ihe glow plugs to Ihe specified torque. Do not overtighten, as this can damage the glow plug element.
3 Preheating system control unit -removal
and
refitting I
Removal 1 Disconnect the battery negative terminal (refer to Disconnecting the baffery In Ihe Reference Section of this manual). 2 Unscrew the screws and remove the relay cover located at the left-hand end of the engine. 3 Disconnect the wiring then remove the control unit from the bracket. Refitting 4 Refitting is a reversal of removal.