What is the cylinder pressure of diesel q7 and how high is the water temperature of diesel version Q

1. Cylinder wear and failure phenomenon.

There is a noticeable clicking knocking sound during the cold start, and the temperature increases, and the sound is weakened or disappears.

The cylinder pressure is low. Sometimes blue smoke is emitted from the exhaust pipe, and blue smoke is emitted from the oil port.

Reduced engine dynamics.

Increased fuel consumption. Fault diagnosis and elimination of cylinder wear.

Second, the wear law of the cylinder and its causes.

1) Cylinder wear law.

From the longitudinal section of the cylinder (along the axis of the cylinder): irregular "cone" or "cone" with large upper and lower size. Wear the most areas:

When the piston is located at the top dead center, the cylinder wall corresponding to the first piston ring, the upper mouth that the piston ring cannot touch is not worn, forming a "cylinder step". In special cases, the greatest wear of the cylinder is in the middle (waist drum shape). On the same engine, the wear of different cylinders is not the same, and the wear of the front wall of the first cylinder and the rear wall of the last cylinder of the water-cooled engine is more serious.

From the cylinder cross-section: uneven wear, worn into an irregular oval. The maximum wear part of each cylinder along the circumferential direction: generally the most wear of the cylinder wall near the opposite side of the intake valve.

2) Causes of cylinder wear.

Under normal conditions, the wear of the cylinder along the working surface in the piston ring movement area is an irregular cone with a large top and a small bottom along the height direction. The largest part of wear is the cylinder wall corresponding to the first piston ring when the piston is in the top dead center position. However, the upper mouth of the piston ring, which is not in contact with the cylinder wall, is almost not worn, resulting in a noticeable cylinder shoulder.

The reasons why the top is big and the bottom is small:

Mechanical wear: When the piston is located at the top dead center, the high-temperature gas burst pressure is the largest, resulting in the positive pressure of the piston ring on the cylinder wall increases, the friction also increases, the lubricating oil film is destroyed, and the cylinder wall wear corresponding to the first piston ring is the most serious.

Corrosion wear: organic acids and acidic oxides (dissolved in water to form mineral acids) from the combustion of gas mixtures. It has a corrosive effect on the surface of the cylinder, resulting in corrosion and wear. The upper part of the cylinder block cannot be completely covered by the lubricating oil film, and the corrosion effect is more serious.

Abrasive wear: Dust in the air, mechanical impurities in the lubricating oil, and abrasive debris in the engine enter the cylinder walls to cause abrasive wear. The dust in the air is sucked into the upper part of the cylinder, which has sharp edges and corners, so the upper part of the cylinder is also the most worn.

The reason for the waist drum shape: in areas with severe wind and sand, after a large amount of dust enters the cylinder, the abrasive wear is the most serious due to the maximum movement speed of the piston in the middle of the cylinder.

3. Cylinder wear fault diagnosis method.

Detection of faulty cylinder pressure.

Inspect cylinder diameter and cylindricity.

Diesel cylinder pressures range from 16 to 22

1. The cooling water in the engine water tank reaches the boiling point, and produces a large amount of water vapor, which will produce a large number of bubbles, and a part of the cooling system is occupied by bubbles, which will make the cylinder wall around the serious water deficit, so that the engine lacks cooling, and will reduce the strength of the piston, piston ring, connecting rod and other components, and even deform, and can not bear the normal load, and at the same time, it will also destroy the normal gap between the parts, so that the normal oil film can not be maintained between the parts, and the engine will pull the cylinder and pull the swag. In other cases, the entire engine can be damaged or even scrapped.

2. Selection of antifreeze: the freezing point of antifreeze is 10 lower than the minimum temperature in winter in the place of residence. The mainstream brand products of antifreeze are basically 40-60 yuan a barrel, with a capacity of 4 liters (the volume of the general car water tank is almost 4L).

The ** of the original concentrated antifreeze may be slightly more expensive, generally about 80 yuan a bottle, and the capacity is about that. When replacing the antifreeze, it is necessary to add it in proportion, and in general, the ratio of antifreeze to water is 1:1 or 1:

A ratio of 2 is sufficient.

3. The replacement cycle and replacement method of antifreeze.

The recommended replacement cycle of the original antifreeze will vary from manufacturer to manufacturer, but the vast majority of them recommend that car owners replace the vehicle antifreeze every 2 years, and some manufacturers show that their original antifreeze replacement cycle is 4 or 5 years. But no matter what, in short, it has to be replaced, which is nothing more than the length of the replacement cycle.

4. When replacing the antifreeze, the first and most important thing is to wait for the vehicle to cool down, and do not replace the antifreeze when the engine is at a high temperature. First, there will be a risk of burns, and secondly, the release of antifreeze during the "hot car" will also affect the cooling of the vehicle.

5. When filling with new antifreeze, you can directly pour about about (depending on the model) of antifreeze into the storage tank, and stop filling after the liquid level height reaches the upper limit max position. At this time, unscrew the drain screw next to the "water pipe", and continue to start filling the antifreeze, see the antifreeze gushing out of the drain screw continuously and without bubbles, and then tighten the drain screw, so far the first time to fill the antifreeze and release the air The work is basically completed.

After starting the vehicle, idle for 3-5 minutes to let the vehicle enter the normal working temperature, and make the new antifreeze can be fully circulated in the waterway in the car, and then turn off the engine, open the reservoir will find that the liquid level height has decreased, then only need to add an appropriate amount of antifreeze to keep the liquid level between max and min.