Checking oil pressure and changing it

Engine oil pressure can be checked using a pressure gauge with an adapter that can be screwed in instead of the oil pressure switch.

The engine has a second oil pressure switch connected to the warning signal. If the oil pressure drops below 0.3 bar, the 0.3 bar oil pressure switch closes and the low oil pressure warning light in the engine lubrication system lights up. If the oil pressure drops below 0.2 bar and the speed remains at 2000 min for more than a second^–1, the oil pressure switch is activated at 0.9 bar. The indicator lamp for insufficient oil pressure in the engine lubrication system lights up and an audible signal sounds. The 0.3 bar oil pressure switch is located in the cylinder block and has brown insulation; The 0.9 bar oil pressure switch is located on top of the filter base.

When checking, both switches should be checked, but it is only possible to establish whether these switches work at all or not. Checking the operation of both oil pressure switches is carried out at the service station.

• check and, if necessary, correct the oil level;
• turn on the ignition. The oil pressure warning light should flash
• start the engine, the oil pressure warning lamp should go out;
• disconnect the cable from the oil pressure switch to 0.3 bar [30 kPa] (brown insulated oil pressure switch) and attach the end of the cable to «mass». The oil pressure warning light should come on;
• install the plug;
• disconnect the plug from the oil pressure switch to 0.9 bar [90 kPa] (oil pressure switch with white insulation).
• let the engine run for more than 1 second at a speed of more than 2000 rpm^–1. The oil pressure warning light should come on and the horn should sound.

The oil pressure switch test procedures described above make it possible to establish that the oil pressure switches are in good working order. To check the oil pressure, use the recommended Volkswagen pressure gauge 1342. The procedure for this or a similar device is shown in fig. 458:

• disconnect the oil pressure switch to 0.9 bar [90 kPa] (with white insulation) and install a manometer;
• connect a pressure gauge instead of an oil pressure switch to the filter base;
• disconnect the brown wire from the 0.9 bar [90 kPa] oil pressure switch and connect the blue wire 1;
• connect test lamp 2 to cable 1 and to terminal «+» AB;
• connect the brown cable 3 of the manometer to ground;
• turn on the ignition;
• start the engine. As soon as the pressure gauge shows a pressure of 0.15-0.45 bar [15-45 kPa], the indicator lamp should go out. Otherwise, replace the oil pressure switch with a new one.

To check the oil pressure switch at 0.9 bar [90 kPa]:

• disconnect wire 1 (pic. 458) from the oil pressure switch to 0.3 bar [30 kPa] and connect it to the oil pressure switch to 0.9 bar [90 kPa] (oil pressure switch with white insulation).
• start the engine, and gradually increase the speed. If at a pressure of at least 0.75-1.05 bar [75-105 kPa] the indicator lamp does not light up, replace the oil pressure switch;
• increase the engine speed to 2000 min^–1 — the pressure must be at least 2.0 bar [200 kPa]. Replace or repair the oil pump if the oil pressure is less than or falls below 0.2 bar [20 kPa].

Engine oil change

Changing the oil is carried out in a similar way to changing the oil in gasoline engines.