Checking the compression in the cylinders (VW Transporter T4)

Compression testing allows you to draw conclusions about the engine condition. Based on the results of the test, you can determine the degree of wear of the valves or pistons (piston rings), and also the need for engine repair. To check, you need a compression gauge, which for gasoline engines can be bought in auto stores.

Attention! For a diesel engine, a compression tester with a large measuring scale is required.

The difference in pressure between individual cylinders must not exceed 3.0 bar (diesel engine 5.0 bar). If one or more cylinders have a pressure difference of more than 3.0 bar (diesel engine 5.0 bar), then this indicates defective valves, wear of piston rings or cylinder walls. When the wear limit is reached, the engine must be overhauled or replaced.

Engine type	Compression pressure, bar
	New	Wear limit
Gasoline engine	9 – 12	7,0
Diesel engine	34,0	26,0

Gasoline engine

1. When checking compression, the engine must be at operating temperature. Oil temperature must be at least 30°C.

2. Turn off the ignition.

3. Disconnect the plug from the Hall sensor on the ignition distributor.

4. Remove fuse #15 from the fuse box.

5. Disconnect all spark plug connectors. There are special pliers for this, for example HAZET 1849. They grip the connector only by the metal sleeve.

6. Blow dirt out of the spark plug recesses in the cylinder head with compressed air and remove all spark plugs with a suitable spark plug wrench.



7. Turn the engine over several times with the starter to remove combustion products.

Attention! Gearbox in neutral position, handbrake applied.

8. Fix or screw the compression gauge into the spark plug hole in the cylinder, according to the instructions for use.

9. Press the gas pedal all the way down and hold it in this position during the entire test. An assistant is needed for this.

10. Crank the engine approximately 8 revolutions until the compression gauge shows a constant pressure.

11. Check all cylinders in sequence and compare the readings with the required values.

12. Tighten the spark plugs and connect the high-tension wires.

13. Connect the plug to the Hall sensor.

14. Install fuse #15.

Diesel engine

Compression measurement

Thermal insulator

1. Warm up the engine while driving until the coolant temperature reaches 80°C.


2. Disconnect the electrical wire from the fuel injection pump switch, insulate it and set it aside.

3. Clean the injection pipes with cold cleaning agent and remove without changing their curved shape.

4. Remove the injectors (see subsection 2.17.7.5).

5. Screw the compression gauge in place of the injector, while installing an old heat insulator between the compression gauge and the cylinder head.

Attention! The pressure data given are valid only when measured with the VW-1381 compression tester with the VW1323/2A adapter. Other devices can only measure the pressure difference between individual cylinders (see fig. Compression measurement).

(The original can be viewed on the portal: «vwmanual.ru»)

6. Turn the engine over approximately 8 revolutions until the instrument reading stabilizes.

7. Screw in the injectors and tighten to a torque of 70 Nm.

Caution! Always replace the heat insulators between the cylinder head and the injectors. The recess must be installed upwards (see fig. Thermal insulator).

8. Tighten the injection pipes to 25 Nm.

9. Connect the wire to the fuel supply switch.