Author: pawel

Engine knocks

The knocking knocks from under the hood just after starting are not cause for concern, however, if they persist after the engine has warmed up, their most common cause is damage to the crankshaft bushings. Much less often they can be the bearings of the main journals. Bearing failure generally entails quite costly engine repair, if the symptoms were noticed in time, it is enough to replace the connecting rod half shells.

Recognition of damage to the shaft bearings.

■ Bring the engine to moderate speed and take your foot off the accelerator pedal. If a slight knocking noise is heard when reducing the engine speed (similar to „nak-nak-nak”) and you can hear similar sounds also when you accelerate vigorously, it should not be delayed with repair.

■ Stop driving. The damage will get worse and then the repair will be much more difficult and more expensive.

■ If there is a loud rattling noise when increasing engine speed (“Clack-clack-clack”), which becomes weaker or inaudible after removing the leg from the accelerator pedal, this is evidence of complete damage to the placenta.

Timing belt and camshaft.

The toothed belt is an important component of the timing system. Its task is to drive the timing thread. It is located outside the crankcase and is located on the camshaft and crankshaft gears. The gear ratio of the drive is 2:1, i.e. the camshaft rotates twice as slowly as the crankshaft. The belt is made of plastic reinforced with steel wires and requires neither lubrication, nor tightening. Volkswagen requires replacement of the timing belt on the engines 1,9 TDI co 90000 km, and in the V6 engine co 120000 km. Replacing the toothed belt is not only laborious, but also a very difficult activity. After replacement, it is necessary to adjust the timing system. It requires, beyond knowledge, many specialized tools (m.in. GMP setting device, setting ruler, gripper with feet, Matra nut wrench). In diesel engines, it is also necessary to set the injection start in the injection pump, as the toothed belt also drives the pump. Incompetent replacement of the toothed belt leads to the most severe damage to the engine. Therefore, this task must be entrusted to a workshop.

 

Belt replacement

Replacing the serpentine belt is quite a laborious activity, especially in the V6 engine, in which you even have to remove the shock absorber and set the front belt in the service position. In a gasoline engine 1,8 Turbo, in which it is necessary to replace the belt every 120000 km, it is better to entrust this operation to a workshop.

Next steps:

1. On all engines, remove the top engine casing (some models also include the lower engine cowl and the right-hand noise-reducing hood). In the engines 1,9 TDI (AGR, AHF, ASV i ALH) the air intake pipe between the air cooler and the turbocharger must be removed.

2. Before removing the poly V-belt, mark the direction of rotation with chalk or a felt-tip pen. If the same belt is put back on, but it will rotate in the opposite direction, this may damage it, and certainly for faster wear. Pay attention when attaching the strap, so that it goes well on the pulleys. Crankshaft rotates clockwise (viewed from the right side of the car).

3. To loosen the belt, tilt the tensioner pulley in the direction of the arrow and, on some engines, the tensioner mechanism with a ring spanner or a spanner 16 mm.

4. Remove the strap. In some solutions, the tensioner mechanism must be locked with a metal pin (diameter 4,5 mm, length 55 mm), inserting it into the locking hole. On cars without headlamp washers, the tensioner crank bracket can be locked with a special V.A.G tool 3090 (see drawings).

5. When refitting the V-belt, place it carefully on the pulleys. Pay attention to the correct installation of the generator, power steering pumps and air conditioning compressors.

6. In diesel engines, in cars without air conditioning, start removing the belt from the alternator pulley (it is located to the right of the tensioner wheel). Also start attaching the strap from this point. On cars with air conditioning, first remove the belt from the reversing pulley and start installing it there as well.

7. After attaching the strap, check its orientation.

8. Start the engine and check for proper belt operation.

Checking the condition of the poly V-belt.

Once a simple V-belt has become a wider, much longer multi-ribbed V-belt. It drives the alternator, power steering pump, radiator fan i (if present) air conditioning compressor.

At first glance it seems, that the belt, routed through a very complicated path, is an integral part of the engine. The serpentine belt is designed to match the engine type. A broken belt means a big complication for the engine, therefore it is extremely durable.

Mandatory belt replacement after each 120 000 kilometers are provided for engines only 1,8 Turbo. It is not compulsory to check the condition of the belt, but it certainly won't hurt him.

Next steps:

1. Check the outside of the belt.

2. Turn the crankshaft several times. This will allow you to see the entire strip. Most often, the bar has only one, but deep damage. To view them, slide the damaged spot over the pulley.

3. Replace the belt when damaged as follows:

■ uneven wear on the side of the belt,

■ a porous or ragged surface of the strip,

■ broken belt.

Checking the belt tension

A belt tensioned too weakly will slide and transmit too little power (or not at all). The belt-driven components will malfunction. Excessive belt tension is also harmful. It places an unnecessary stress on the component bearings.

The engines of Golf and Bora cars feature automatic belt tension adjustment. The tightness is checked as follows.

Press very hard on the stretched belt. It must give way under pressure and the tensioner pulley should swing sideways. When you release the pressure, the pulley should return to its starting position and tighten the belt. If the belt starts to hang loose, this indicates that the tensioner is damaged or the multi-wedge pin locking the tensioner has not been pulled out.