Cylinder Compression Check Nissan Primera 2001-2007

Tools:

• Compressometer

• Pen (office)

Parts and consumables:

• Paper

Note :

Compression (pressure at the end of the compression stroke) in the cylinders is the most important indicator for diagnosing the condition of the engine without disassembling it. By its average value - and by the difference in value in individual cylinders, it is possible to determine with a sufficient degree of accuracy the degree - of the general wear of the parts of the connecting rod and piston group of the engine, to identify malfunctions of this group and parts of the valve mechanism.

They check the compression with a special compression tester, which can now be freely purchased at large auto parts stores.

An important condition for the correctness of the readings when checking the compression is the serviceability of the starter and its electrical circuits, as well as the full charge of the battery.

1.  Start the engine and warm it up to operating temperature.

2. Reduce the pressure in the supply system. After depressurizing - do not replace the fuel pump fuse to shut off the fuel pump.

Z.  Remove the ignition coils and turn out all the candles. More details here .

4. Insert and hold the compression tester by hand or screw it into the spark plug hole of the cylinder being checked.

5.  Fully depress the accelerator pedal to fully open the throttle.

6.  Turn on the starter and rotate the engine crankshaft until the pressure in the cylinder stops increasing. This corresponds to about four compression strokes.

Note:

To obtain the correct readings - the compression gauge, the crankshaft must rotate at a frequency of 180-200 rpm or higher, but not more than 350 rpm.

7. We write down the readings of the compression gauge.

8. Set its pointer to zero by pressing the air release valve.

Note:

For compression meters of a different design, readings can be reset in other ways in accordance with the instructions for the device.

9.  Repeat steps. 4-8 for other cylinders. The pressure should not be lower than 1.0 MPa and should not differ in different cylinders by more than 0.1 MPa.

10. Reduced compression in individual cylinders can result from loose valves in the saddles, damaged cylinder head gaskets, broken or burned piston rings. Low compression in all cylinders indicates worn piston rings.

11. To find out the causes of insufficient compression, pour about 20 ml of clean engine oil into the cylinder with reduced compression and measure the compression again. If the readings of the compression gauge have increased, the most likely malfunction of the piston rings. If the compression remains unchanged, it means that the valve plates do not fit snugly against their seats or the cylinder head gasket is damaged.

USEFUL TIPS

The cause of insufficient compression can also be found out by supplying compressed air to the cylinder in which the piston is previously set to TDC of the compression stroke. To do this, remove the tip from the compression gauge and attach the compressor hose to it. Insert the tip into the spark plug hole and inject air into the cylinder at a pressure of 0.2 - 0.3 MPa. To prevent the engine crankshaft from turning, engage a higher gear and brake the vehicle with the parking brake. The exit (leakage) of air through the throttle assembly indicates that the intake valve is not tight, and through the muffler - that the exhaust valve is not tight. If the cylinder head gasket is damaged, air will escape through the neck of the expansion tank in the form of bubbles or into an adjacent cylinder, which is detected by a characteristic hissing sound.

The article is missing:

• Tool photo
• Photo of parts and consumables
• High-quality repair photos

Source: Nissan Primera P12 Operation, Maintenance and Repair Manual. Publishing house "Third Rome".