The cylinder bores are bored in the cylinder block made of gray cast iron. For a 6-cylinder engine, designated 6VR, the cylinders, like an in-line engine, are located in one block, but in a V-shape, with an angle between the planes of the cylinders equal to 15". In case of significant wear or unevenness of the cylinder walls, the cylinders can be honed and ground in a specialized workshop. Of course, after this, pistons of increased diameter should be installed. At the bottom of the cylinder block is the crankshaft, which is attached to the block by means of five (for the 6VR engine - by means of seven) main bearings. Plain bearings are installed between the connecting rod journals of the crankshaft and the connecting rods connected with the pistons. An oil pan closes the lower part of the engine, in which the engine oil necessary for lubrication and cooling is collected. From above, a cylinder head made of light alloy is attached to the cylinder block. Compared to cast iron, the aluminum alloy of the cylinder head has a higher thermal conductivity and a lower specific gravity.
In 4-cylinder engines with two valves per combustion chamber, there is one camshaft at the top of the cylinder head to control the valves. In 4-cylinder engines with four valves per combustion chamber, as well as in 6VR engines, there are 2 camshafts. The camshaft is driven from the crankshaft by a toothed belt (in 6VR engines - using a chain). The camshaft controls the vertical intake and exhaust valves via hydraulic poppets. Hydraulic tappets automatically equalize valve clearances, eliminating the need to adjust valve clearances for service.
Engine lubrication is provided by an oil pump located in the oil pan and driven from the crankshaft through the intermediate shaft. The oil taken from the oil pan is fed through channels to the bearings of the crankshaft and camshaft, as well as to the working surfaces of the cylinders.
The coolant pump is located on the side of the cylinder block and is driven by a V-belt or V-ribbed belt, which also drives the generator. An additional V-belt drives the power steering pump. It must be borne in mind that the coolant, regardless of the season, should be a mixture of soft water with antifreeze and anti-corrosion additives.
To prepare a combustible fuel-air mixture, a carburetor or fuel injection system is installed, which, as a rule, does not require maintenance during operation.
The electrical spark is generated by a transistorized ignition system that keeps the ignition timing constant. The ignition distributor is attached to the side of the cylinder block and is driven by an intermediate shaft with splined engagement. In turn, the intermediate shaft is driven by a gear from the crankshaft.
In the presentation of the material in each chapter, it is indicated which engines this applies to, 4-cylinder engines have a great similarity in design, the differences relate primarily to the design of cylinder heads with eight and sixteen valves. For this reason, it is first necessary to establish, using the table on the following page, which design the given motor has.
Warning: The radiator fan may also come on when the engine is stopped and the ignition is off. This is caused by heat buildup in the engine compartment and can happen multiple times. Therefore, when working in the engine compartment and a warm engine, always take into account the possibility of unexpected activation of the radiator fan.
The engine number and letter designation for 4-cylinder engines are embossed on the left side of the cylinder block (2).
The engine number and letter designation for 6VR engines are stamped on the side of the cylinder block opposite the gearbox.
Nameplate with product model designation (1) located in the engine compartment on the right side. The chassis number is stamped on the right next to the plate on the rear cross wall.
Chassis number decoding
- 1 - international designation of the manufacturer (WVW = VW AG - VW joint-stock company)
- 2 - execution designation, except for models for delivery to the USA
- 3 is a two-digit abbreviated designation of the model, made up of the first two positions of the official designation of the model. 31 = PASSAT4.88-7.93, FOR = PASSAT from 8.93
- 4 - designation of another version
- 5 - year of manufacture of the model: J = 1989, K = 1990, etc.
- 6 - place of production within the VW concern: W - Wolfsburg, E - Emden, A - Ingolstadt, N - Neckarsulm, K - Osnabrueck, B - Bruessel.
- 7 - serial number of the product; each model year starts with 000001.
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