Engine

The Fiat Bravo/Brava is powered by liquid-cooled in-line engines installed transversely in the engine bay. All engine versions have a cast-iron engine block. The cylinder head is made of light alloy. The advantages of a light-alloy cylinder head over a cast-iron one are better thermal conductivity and lower specific weight.

The cylinder bores are machined into the engine block.

In case of heavy wear or scoring in the cylinder walls, the cylinders can be honed, i.e. bored out, by a specialist workshop. Oversize pistons must then be fitted. In the lower part of the engine block is the crankshaft, which is supported by the main bearings. The connecting rods, which link the pistons to the crankshaft, are connected via plain bearings. Coolant flows through the engine block. The coolant pump is flanged onto the side of the engine block. Please note that the cooling system must be filled year-round with a mixture of antifreeze coolant and low-lime water.

The engine is closed off at the bottom by the oil sump, in which the engine oil required for lubrication and cooling collects. Oil drawn in from the oil sump passes through bores and passages to the crankshaft and camshaft bearings and into the cylinder bores.

The cylinder head is bolted onto the engine block. It is made of aluminium alloy with pressed-in steel valve seat inserts and valve guides. The cylinder head is designed on the cross-flow principle. This means that fresh fuel-air mixture is drawn in on one side of the cylinder head, and burnt gas is expelled on the other side through the exhaust system. The cross-flow arrangement ensures rapid gas exchange through the intake and exhaust valves. Using several intake and exhaust valves per cylinder speeds up gas exchange further.

At the top of the cylinder head are two camshafts (1.4 L engine and diesel: one camshaft), which are driven by the crankshaft via a timing belt. The camshafts actuate the vertically hanging intake and exhaust valves. On petrol engines, hydraulic valve lash adjusters maintain a constant valve clearance between camshaft and valve, so the valve clearance cannot be adjusted. Only the diesel engine has bucket tappets with adjusting shims, and the valve clearance must be adjusted as part of maintenance.

Five different engine types are used:

The 1.4 L engine belongs to the new "modular" engine family. It is essentially based on the "Fire" engine, which was first used in various Fiat models in 1985.

The most significant change is the cylinder head, which has two intake valves and one exhaust valve per cylinder. The camshaft actuates the 12 valves via rocker arms, which are supported on maintenance-free valve lash adjusters.

An oil pump located at the end of the crankshaft and driven by it provides engine lubrication. The coolant pump is driven by the timing belt, which also drives the camshaft.

The base engine for this unit is the 1.6 L "Torque" engine from the predecessor model, the Fiat Tipo, which has been revised. It now has two overhead camshafts, which actuate the 16 valves directly via hydraulic bucket tappets.

In addition to the camshaft, the timing belt also drives an auxiliary shaft, which drives the oil pump via helical gearing. The coolant pump is driven by the poly-V belt, which also drives the alternator.

The 1.8 L engine belongs to the new "modular" engine family. Its design is defined by the two overhead camshafts, which actuate the 16 valves directly via hydraulic bucket tappets. As with the 1.4 L engine, the coolant pump is driven by the timing belt, which also drives the camshafts. The oil pump is located at the end of the crankshaft.

The newly developed 2.0 L engine has 5 cylinders and 20 valves, which are actuated by 2 camshafts via maintenance-free hydraulic tappets. Depending on engine speed, the intake camshaft is rotated relative to the timing belt sprocket by an adjustment unit, so that optimum valve timing is achieved. The adjustment unit is controlled by the engine control unit. In addition to the camshafts, the timing belt also drives the coolant pump.

The crankshaft drives the oil pump and a counter-rotating balance shaft via a chain. The balance shaft turns at the same speed as the crankshaft, and targeted imbalance largely avoids unwanted engine vibrations across all speed ranges.

To remove the timing belt, the 5-cylinder engine must be removed completely, as there is not enough space in the engine bay for disassembly. Work such as removing the cylinder head or the coolant pump also cannot be carried out without first removing the engine.

The camshaft timing belt tension is kept constant by an automatic tensioner, so it does not need to be retensioned. The poly-V belt driving the auxiliary units (alternator, power steering pump, etc.) is also tensioned automatically, except on the 1.6 L engine.

Maintenance-free, electronically controlled systems are fitted for mixture preparation and ignition of the petrol-air mixture. The electronic ignition and fuel injection systems guarantee long-term stable exhaust emission values.

The "static ignition system" with individual ignition coils has no moving parts, so it operates wear-free.

The diesel engine has a single overhead camshaft. Valve clearance must be checked as part of maintenance. The coolant pump is driven by the V-belt, and the oil pump is located directly at the end of the crankshaft. A distributor-type fuel injection pump flanged to the side of the engine block provides diesel injection. The injection pump is driven by the timing belt, which also drives the camshaft. Electronically controlled fuel injection ensures low exhaust values and low consumption.

Each repair instruction states which engines it applies to. Where possible, the work steps have been combined.