Fiat Uno Manual
Cooling systemSupplement: Revisions and information on later models / Cooling system
999 AND 1108 CC ENGINES
1 The operation and function of the cooling system is essentially as described in Chapter 2 but note the location of the various components and the routing of the coolant hoses in Fig. 13.26.
2 Topping-up, draining and refilling procedures are as for 1116 and 1301 cc engines in Chapter 2, but note that the coolant capacity is different (see Specifications).
removal and refitting
3 The thermostat is located on the left-hand end of the cylinder head, below the distributor.
4 The thermostat cannot be renewed independently of its housing and if faulty the complete assembly must be renewed.
5 Drain the cooling system.
6 Although the thermostat housing can be removed directly from the cylinder head, better access is provided if the distributor is first withdrawn as described in Section 10 of this Chapter (photo).
8A.6 The thermostat housing (shown with distributor removal) on the 999 cc engine
7 Disconnect the coolant hose from the thermostat housing and unscrew the housing flange bolts. Remove the assembly. Note that it may be necessary to tap it free with a plastic-faced or wooden mallet if stuck in place.
8 Remove the gasket and clean the mating surfaces.
9 Use a new gasket and bolt the assembly into position (photo).
8A.9 Fitting the thermostat housing. Note the new gasket
10 Reconnect the coolant hose, then fill and bleed the cooling system.
Coolant pump -
removal and refitting
11 The coolant pump is located on the crankshaft pulley end of the engine and is driven by the timing belt.
12 The pump cannot be repaired and must be regarded as disposable.
13 Drain the cooling system.
14 Remove the timing belt cover and then set No. 1 piston to TDC. To achieve this, turn the crankshaft pulley bolt until the camshaft sprocket timing mark is aligned with the one on the cylinder head.
15 Release the belt tensioner and slip the timing belt off the camshaft and coolant pump sprockets.
16 Unbolt and remove the coolant pump and clean the mounting face of all old gasket material.
17 Apply a continuous bead of RTV silicone sealant (instant gasket) to the mounting face of the coolant pump and bolt it into position (photos).
8A.17A Fitting the coolant pump to the 999 cc engine
8A.17B Tightening the coolant pump bolts
18 Check that the camshaft sprocket and the crankshaft have not been moved and fit the timing belt to the camshaft and coolant pump sprockets. The pump sprocket does not require setting in any particular position before connecting the timing belt.
19 Tension the belt as described in Section 5B of this Chapter.
20 Fit the timing belt cover.
21 After allowing one hour for the gasket material to cure, refill and bleed the cooling system.
Fig. 13.26 Cooling system circuit - 999 and 1108 cc engines (Sec 8A)
1 Coolant pump
3 Heater matrix
Fig. 13.27 Cooling system thermostat in open and closed positions - 999 and 1108 cc engines (Sec 8A)
Fig. 13.28 Sectional view of the coolant pump on the 999 and 1108 cc engines (Sec 8A)
1301 CC TURBO IE ENGINE
1 The cooling system on this model has flow and return connections to the turbocharger, and is an essential means of cooling the turbocharger.
2 The radiator cooling fan is of two-speed type, being controlled by a two-stage thermostatic switch screwed into the radiator side tank.
3 According to the coolant temperature level, the fan speed is regulated to provide the most effective cooling.
4 The remote cooling system expansion tank is mounted in the left-hand rear corner of the engine compartment (photo).
8B.4 Topping up the expansion tank with antifreeze on the 1301 cc engine
1372 CC IE AND 1372 CC
TURBO IE ENGINES
1 The cooling system layout and components for the 1372 cc engines is shown in Figs. 13.29 and 13.30.
2 The system on each engine operates in essentially the same manner as that described for the other models in Chapter 2, but the location of components and the coolant hose routings differ according to model. The cooling system expansion tank location differs according to model, being either located on the side of the radiator or mounted separately on the side of the inner wing panel.
3 On Turbo models, the cooling system also assists in cooling the turbocharger.
4 The maintenance procedures are essentially the same as those described for the other models in Chapter 2.
Cooling system - draining,
flushing and refilling
Warning: Wait until the engine is cold before starting this procedure. Do not allow
antifreeze to come into contact with your skin or 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. Antifreeze is fatal if ingested.
5 Disconnect the battery negative lead.
6 Working inside the vehicle, turn the heater temperature control knob fully to the right, which will fully open the heater coolant valve.
7 With the expansion tank cap removed, place a suitable container beneath the radiator bottom hose.
8 Loosen the clip and ease the bottom hose away from the radiator outlet (photo). Allow the coolant to drain into the container.
8C.8 Bottom hose connection to the radiator
9 Reposition the container under the front of the cylinder block, and unscrew the cylinder block drain plug (photo). Allow the coolant to drain into the container.
8C.9 Cylinder block drain plug
10 Apply suitable sealant to the threads of the drain plug, then refit and tighten the plug.
11 Dispose of the drained coolant safely, or keep it in a covered container if it is to be re-used.
12 If required, the system can be flushed through as described in Section 2 of Chapter 2.
13 Before attempting to refill the cooling system, make sure that all hoses have been reconnected, that the hoses and clips are in good condition, and that the clips are tight.
Also ensure that the cylinder block drain plug has been refitted and tightened. Note that an antifreeze mixture must be used all year round to prevent corrosion of the engine components - refer to Section 3, Chapter 2.
14 Open the bleed screw in the top of the expansion tank (photo).
8C.14 Bleed screw location on top of the expansion tank (arrowed)
15 Remove the expansion tank cap, and fill the system by slowly pouring the coolant into the expansion tank to prevent air locks from forming.
16 Top up the coolant until liquid free from air bubbles emerges from the radiator bleed screw orifice, then close the bleed screw.
17 Continue topping up until the coolant reaches the Maximum mark on the expansion tank.
18 Start the engine and run it until it reaches normal operating temperature, then stop the engine and allow it to cool. Normal operating temperature is reached when the cooling fan cuts into operation. Feel the radiator top hose to ensure that it is hot. If cool, it indicates an air lock in the system.
19 Check for leaks, particularly around disturbed components. Check the coolant level in the expansion tank, and top up if necessary. Note that the system must be cold before an accurate level is indicated. There is a risk of scalding if the expansion tank cap is removed whilst the system is hot.
Radiator (and cooling fan)
- removal and refitting
20 Disconnect the battery negative lead.
21 Detach the wiring connectors from the cooling fan and the fan switch located in the radiator (photos).
8C.21A Cooling fan and wiring connector
8C.21B Cooling fan switch wiring connector
22 If preferred, the cooling fan unit can be removed separately from the radiator, by undoing the attachment bolts and carefully withdrawing the unit upwards from the vehicle. Take care not to damage the radiator core as it is lifted clear (photo).
8C.22 Cooling fan to radiator securing bolt
23 Drain the cooling system as described earlier in this part of the Section, but note that it will not be necessary to remove the cylinder block drain plug.
24 Undo the retaining screws and remove the front grille panel.
25 Loosen off the retaining clips and detach the upper coolant hose and the expansion hose from the radiator.
26 Note their direction of fitting, then prise free the radiator retaining clips. Carefully lift the radiator from the car.
27 Refitting is a reversal of the removal procedure. Ensure that as the radiator is lowered into position, it engages in the two rubber location grommets.
28 With the radiator (and cooling fan) refitted, top up the cooling system as described earlier in this Section (photo).
8C.28 Topping up the radiator coolant level on the 1372 cc ie engine. Note orientation of radiator retaining clip (arrowed)
removal and refitting
Note: A new thermostat cover gasket must be used on refitting.
29 Drain the cooling system as described earlier in this Section, but note that there is no need to drain the cylinder block.
30 Disconnect the coolant hoses from the thermostat cover (situated at the gearbox end of the cylinder head).
31 Unscrew the two thermostat cover securing bolts, noting that the left-hand bolt may also secure the HT lead bracket, and remove the thermostat/cover assembly.
Recover the gasket (photo).
8C.31 Thermostat unit removal on the 1372 cc ie engine (distributor removed for clarity)
32 If faulty, the thermostat must be renewed complete with the housing as an assembly.
33 If desired the thermostat can be tested as described in Chapter 2.
34 Refitting is a reversal of removal, bearing in mind the following points.
35 Clean the mating faces of the thermostat cover and cylinder head, and use a new gasket when refitting the cover.
36 Refill the cooling system as described earlier in this Section.
Coolant pump -
removal and refitting
Note: A new coolant pump gasket must be used on refitting. If the pump is found to be worn it must be renewed as a complete unit as dismantling and repair is not possible.
37 Disconnect the battery negative lead.
38 Drain the cooling system as described earlier in this Section.
39 Remove the coolant/alternator drivebelt as described in the next sub-Section.
40 Unscrew the four coolant pump securing bolts, noting that two of the bolts also secure the alternator adjuster bracket, and withdraw the pump from the housing (photo). Recover the gasket.
8C.40 Coolant pump/alternator bracket bolt removal
41 Refitting is a reversal of removal, bearing in mind the following points.
42 Use a new gasket between the pump and the housing.
43 Refit and tension the coolant pump/alternator drivebelt as described in the next sub-Section.
44 On completion, refill the cooling system as described earlier in this Section.
drivebelt - checking,
renewal and tensioning
45 At the intervals specified in Section 3 or “Routine maintenance” at the beginning of this manual (as applicable), the drivebelt should be checked and if necessary re-tensioned.
46 Access to the drivebelt is made from the underside of the car on the right-hand side.
Loosen off the front right-hand roadwheel retaining bolts, then raise and support the car on axle stands at the front. Remove the front roadwheel on the right-hand side.
47 Remove the underwing shield from the right-hand wheel arch by drifting the compression pins out from the retaining clips. Prise free the clips and remove the shield.
48 Additional, though somewhat restricted, access can be obtained from above by removing the air cleaner unit on the non-Turbo ie-engine (photo).
8C.48 Top side view of water pump, alternator and drivebelt
49 Check the full length of the drivebelt for cracks and deterioration. It will be necessary to turn the engine in order to check the portions of the drivebelt in contact with the pulleys. If a drivebelt is unserviceable, renew it as follows (photo).
8C.49 Alternator/water pump drivebelt and tensioner viewed from the right-hand wheel arch
50 Loosen the alternator mounting and adjuster nuts and bolts and pivot the alternator towards the cylinder block.
51 Slip the drivebelt from the alternator, coolant pump and crankshaft pulleys.
52 Fit the new drivebelt around the pulleys, then lever the alternator away from the cylinder block until the specified belt tension is achieved. Lever the alternator using a wooden or plastic lever at the pulley end to prevent damage. It is helpful to partially tighten the adjuster nut before tensioning the drivebelt (photo).
8C.52 Fitting a new coolant pump/alternator drivebelt around the pulleys
53 When the specified tension has been achieved, tighten the mounting and adjuster nuts and bolts (photo).
8C.53 Tightening the alternator adjuster nut
Fig. 13.29 Cooling system circuit - 1372 cc ie engine (Sec 8C)
Fig. 13.30 Cooling system circuit - 1372 cc Turbo ie engine (Sec 8C)
1 Electric fan
4 Coolant supply hose (inlet manifold to heater matrix) 5 Heater matrix
6 Coolant return hose (heater matrix to the manifold pipe) 7 Coolant pump
8 Coolant manifold pipe
9 Coolant supply hose (cylinder block/crankcase to the turbocharger) 10 Coolant return hose (turbocharger to the expansion tank) 11 Coolant supply hose (expansion tank to the manifold pipe) 12 Expansion tank
13 Coolant return hose (radiator to the manifold pipe) 14 Fan thermostatic switch 15 Coolant supply hose (thermostat to the radiator) 16 Coolant return hose (radiator to the expansion tank)
PART D: HEATER UNIT- LATER
Heater unit -
removal and refitting
1 The heater unit is removed complete with the facia/control panel. Commence by draining the cooling system as described previously in this Section.
2 Disconnect the battery negative lead.
3 Refer to Section 15 of this Chapter for details and remove the ashtray/cigar lighter and the auxiliary control panel.
4 Undo the upper screw retaining the heater unit to the facia (see Fig. 13.31).
5 Remove the radio from the central facia.
6 Undo the retaining screw on each side at the front of the gear lever console. Prise free the trim cover, undo the retaining screw at the rear of the console. Prise free and release the gear lever gaiter and lift clear the central console.
7 Undo the retaining screws and remove the steering column upper and lower shroud.
8 Detach and remove the lower facia trim on the side of the central facia.
9 Referring to Fig. 13.32, unscrew and remove the four heater facia to main facia retaining screws from the points indicated.
10 Undo the two retaining nuts securing the heater to the body on the driver’s side.
11 Undo the retaining screws and remove the pipe shield from the side of the heater unit, then disconnect the coolant supply and return hoses from the heater. As the hoses are detached, be prepared to catch any remaining coolant as it flows from the hoses and heater connections.
12 Undo the remaining two heater unit securing nuts and withdraw the heater unit from the car. As the unit is removed, detach the wiring and position the hoses with their ends pointing upwards to avoid further coolant spillage.
13 Refit in the reverse order of removal.
Ensure that the hoses are securely reconnected. Top up the cooling system on completion.
Heater unit - dismantling
14 Remove the heater unit as described previously.
15 Pull free the heater/fresh air and blower control knobs (photo).
8D.15 Pull free the heater/fresh air and blower control knobs
16 Undo the two retaining screws and withdraw the control panel from the facia.
Detach the wiring connectors from the panel illumination lights and remove the panel.
17 Unscrew the retaining bolts and remove the centre panel from the heater unit.
18 Undo the retaining screws and remove the control lever mounting.
19 Loosen off the grub screws and detach the cables from the control levers.
20 Undo the retaining screws and remove the control valve.
21 Undo the two retaining screws and withdraw the heater matrix from the heater housing.
22 To separate the casing halves, drill out the pop rivet securing the mounting bracket, release the retaining clips and unscrew the securing bolts.
23 Reassemble in the reverse order of dismantling. Check that the control cables are correctly adjusted and that the controls operate in a satisfactory manner before refitting the heater unit to the car.
Fig. 13.31 Removing the heater unit-tofacia upper retaining screw (Sec 8D)
Fig. 13.32 Heater unit facia to main facia retaining screw locations (arrowed) (Sec 8D)
Fig. 13.33 Heater pipe shield securing screw positions on later models (Sec 8D)
Fig. 13.34 Heater unit components on later models (Sec 8D)
1 Coolant inlet tap
2 Centre panel
3 Side casings
4 Heater matrix
5 Blower fan