Contents: Motor housing 🠛 Crankshaft 🠛 Connecting rod 🠛 Cylinders 🠛 Cylinder head gasket 🠛 Cylinder head 🠛 Valves 🠛 Valve drive 🠛 1.4-liter C-engine 🠛 F-engine: petrol and diesel 🠛 16-valve engine 🠛 Pushrod function with hydraulic…🠛 Camshaft drive chain (C-engine) 🠛
Before starting work on engine repair and maintenance, find and remember the designations of its most important parts and components.
Rear view of C-engine (if you look in the direction of movement)
1 - air filter; 2 - rocker arm of the valve timing mechanism; 3 - valve with spring; 4 - push rod; 5 - valve tappet; 6 - camshaft; 7 - flywheel; 8 - connecting rod; 9 - main bearing; 10 - oil pump oil inlet pipe; 11 - cylinder liner; 12 - pistons; 13 - exhaust manifold of the muffler; 14 - intake manifold; 15 - carburetor (on the C-engine considered in the book it is replaced by an injection system).
Sectional view of the 1.8-liter F-engine
1 - intake manifold pipes; 2 - carburetor (on the F-engine considered in the book it is replaced by an injection system); 3 - air supply and exhaust pipes from the engine; 4 - exhaust manifold of the muffler; 5 - flywheel; 6 - camshaft; 7 - inlet valve; 8 - Timing belt pulley of the camshaft; 9 - Timing belt tension roller; 10 - generator; 11 - toothed belt drive roller; 12 - servo pump pulley; 13 - coolant pump pulley; 14 - crankshaft pulley; 15 - connecting rod; 16 - additional shaft of the oil pump.
Sectional view of a 16-valve engine
1 - ignition distributor; 2 - camshaft with hydraulic compensators; 3 - spark plugs; 4 - exhaust valve; 5 - exhaust manifold; 6 - piston; 7 - crankshaft; 8 - oil pan; 9 - intake manifold; 10 - intake camshaft pulley; 11 - intake air temperature sensor; 12 - toothed belt; 13 - generator; 14 - V-belt; 15 - coolant pump pulley; 16 - suction neck of the oil pump.
Sectional image of a diesel engine
1 - intake manifold; 2 - brake booster vacuum pump; 3 - camshaft; 4 - valve with spring and plate tappet; 5 - pistons; 6 - connecting rod; 7 - flywheel with clutch; 8 - crankshaft; 9 - generator; 10 - high pressure fuel pump (HPFP); 11 - toothed drive belt casing.
[This article is taken from the website RENAULTBOOK.ru]
Motor housing
The body of all the engine types discussed in this book is made of cast iron. The crankshaft is located in its lower part; above - cylinders (four in a row). The cylinders are surrounded by coolant passages. These passages are also present in the upper part of the engine.
Crankshaft
It converts the reciprocating motion of the cylinders into rotary motion. It is connected to the cylinders by means of connecting rods, each of which is attached to the corresponding "knee" of the shaft by means of replaceable liners. The mass of the eccentric knees and connecting rods is equalized by counterweights.
Connecting rod
To regulate combustion, the pistons have, depending on the engine type, different recesses in the upper part of the piston. In the upper third of each piston there are piston rings, which are elastically fixed in grooves on the piston. They press on the cylinder wall. The two upper piston rings close the path of the gas mixture from the combustion chamber down into the engine crankcase, and the lower oil scraper ring prevents oil from the crankcase from getting into the piston chamber.
Cylinders
On the 1.4-liter C-type engine, piston liners are mounted in the engine cylinder bores. They are washed with coolant. Therefore, they are called "wet" cylinder liners. Worn-down liners can be replaced, although in this case, it is also necessary to replace the pistons.
Both the 1.7-/1.8-liter, 16-valve engines and the diesel (F-engine) the cylinders are part of the engine body. The cylinders are fitted with liners that are adjusted to the piston diameter. When repairing an engine, the holes are bored out by several tenths of a millimetre to eliminate traces of wear. Pistons must be selected for bored cylinders. This is not difficult to do, as there is a wide range of sizes.
Cylinder head gasket
It protects the oil and coolant channels from the high pressure from the combustion chambers. One of the most important parts in diesel engines is the cylinder head gasket. Since the gasket separates the cylinder block and the cylinder head, it is possible, depending on its thickness, to vary the height of the combustion chamber and thus compensate for the difference in piston height.
Cylinder head
The cylinder head contains a labyrinth of coolant channels. The cylinder head on all Renault 19 engines is made of aluminum alloy. The cylinder head made of light metal has high thermal conductivity and therefore provides, especially on a gasoline engine, better cooling of the working mixture. A colder working mixture provides a higher compression ratio. At the same time, there is no detonation. Depending on the engine type, the combustion chambers have different shapes. Particularly important is the absence of protrusions and irregularities in the combustion chamber to ensure a high gas flow rate. This allows you to achieve an optimal ratio of air and fuel in the working mixture and achieve complete combustion of the fuel. The passage of the mixture on a 16-valve engine is arranged according to the principle of transverse scavenging, with an inlet at the front and an outlet at the rear of the engine. With transverse scavenging, the burnt fuel is removed from the combustion chamber faster during the power stroke, since it moves along the shortest path. As a result, the cylinders of the suction side are filled with the working mixture faster - which leads to an increase in engine power.
the 1.7-, 1.8-liter petrol engines and diesel are equipped with a counter-flow cylinder head. This type of cylinder head has the inlet and outlet channels on the same side. On the Renault 19, this side of the cylinder head faces the front wall of the body. This makes it difficult to bring in fresh air and release exhaust gas. However, this has significant advantages for the turbocharging of the diesel engine, since the air moves along the shortest path.
Valves
The 1.4-liter C engine has valves arranged in a row and actuated by pushrods and rocker arms from a camshaft located slightly to the side. On modern F engines, the camshaft, located at the top of the cylinder head, acts on the valves arranged in a row in the cylinder head directly by means of cup tappets. On a 16-valve engine, there are 2 exhaust and 2 intake valves per cylinder, which are pressed by paired cams, the cup tappets of which have hydraulic clearance adjustment, which makes it possible to do without adjustment of the clearance in the valve train on these engines.
Valve drive
All units involved in opening and closing the valves are called "valve drive". The function of the valves is to open and close the inlet and outlet ports in the cylinder head to admit the working mixture or release the exhaust gases. At a certain point, both cylinder valves are closed. In a short period of time, the mixture is ignited by a spark in a car with a gasoline engine or fuel is injected through an injector in a diesel. When the inlet and outlet valves work in concert with the movement of the pistons, the engine develops full power.
1.4-liter C-engine
In the C engine, the camshaft is located slightly to the side of the engine housing. It operates the valves via pushrods and valve levers. The camshaft is attached in four places and is driven by a short roller chain with a mechanical tensioner. In the center of the camshaft is a toothed wheel that drives the distributor and oil pump. High pushrods move along cam guides. They contain pushrods that, via valve levers, operate the valves located parallel in the cylinder head. The clearance in the valve train is set by tightening the rocker arm bolts.
F-engine: petrol and diesel
On these engines, the camshaft is located in the upper part of the housing and is attached in five places. It is driven by a toothed drive belt from the crankshaft. At the same time, the toothed belt rotates the intermediate shaft of the oil pump. In a diesel engine, the high-pressure fuel pump is also driven by this belt. The camshaft acts on the valves using cup tappets. The clearance in the valve drive is not adjustable, but is set by replacing the mounting plate in the cups of the valve tappets.
16-valve engine
The 16-valve engine has two camshafts in the upper part of the cylinder head. Each shaft is attached at five points. Both camshafts are driven by a toothed belt from the crankshaft. The toothed belt has a tensioner. At the same time, the toothed belt drives the intermediate shaft for the oil pump.
Each cylinder has 2 intake and 2 exhaust valves. The V-shaped valves are actuated by cup tappets with hydraulic clearance adjustment.
Note: Recommendation: for hydraulic (automatic) when adjusting the clearance in the valve drive, manual adjustment is not performed; the valve drive on a 16-valve engine is not serviced.
Pushrod function with hydraulic clearance adjustment
When the valve is closed, oil from the engine lubrication system flows through the annular groove into the plate tappet. After passing the check valve in the tappet, the oil flows into the high-pressure chamber and fills it. At the same time, the pressure spring moves the cup tappet toward the camshaft and locks the cylinder of the high-pressure chamber with the end of the valve stem. When the camshaft rotates and its eccentric cam presses on the cup tappet, the pressure in the high-pressure chamber increases. The check valve closes the inlet port and the oil cannot flow out. Since the oil is not compressed, a fixed joint is formed between the tappet and the cylinder. After the valve closes, a small gap in the valve train occurs due to the loss of oil, which, however, will be immediately compensated again by the pressure spring of the high-pressure chamber. Oil flows into the vacated volume of the chamber again with the check valve open. Thus, the hydraulic tappet is ready for operation again.
Camshaft drive chain (C-engine)
The crankshaft drives the camshaft via the drive chain. This chain is the "weakest" link in the valve train, as it is most susceptible to wear. As the mileage increases, the chain stretches, which is compensated to a certain extent by the chain tensioner. If a ringing sound is heard at idle on the 1.4-liter C-engine, the cause is the camshaft drive chain.
Toothed drive belt
An important part of the valve drive on Renault 19 F-engines is the toothed drive belt. The Renault engine designers chose this conventional drive mechanism because it has a longer service life and is also quiet.
The obvious advantage: the toothed belt is very flexible, so additional devices can be driven with it (water pump, oil pump, etc.).