How to adjust the valve clearance of 4 cylinder, 6 cylinder, 8 cylinder gasoline and diesel vehicles

There are two ways to adjust the valve of a four-cylinder diesel car

Turning car, that is, pry belt disc to 1 cylinder top dead center, see the fuel injection pump and flywheel disc generally have marks, the specific judgment varies depending on the engine, at this time you can adjust 1 into 1 row, 2 into 3 rows, rotate the crankshaft 360 °, that is, the fuel injection pump 180 °, adjust the remaining valves.

Loosen the 4 high-pressure pipes of the high-pressure pump, and stop the cranking of the oil from the crank to the flange of the high-pressure pump as soon as it begins to fluctuate.

Adjusting the cylinder needs to be carried out in the cold state, the valve clearance varies from engine to engine, and the general exhaust is larger than the intake air, that is, the intake air, the exhaust is left and right, and the specific reference engine parameters are made.

Experienced masters generally use one method to adjust and another method to check it again to ensure that nothing goes wrong.

Using two adjustment methods, the work sequence of the 6-cylinder engine is generally to open the cylinder cover cover, rotate the crankshaft, see the movement of the 6-cylinder valve, when the intake and exhaust valves have overlapping movements, it is the exhaust top dead center of the 6 cylinders, at this time the 1 cylinder is in the compression top dead center, you can adjust the intake and exhaust valves of the 1 cylinder, the intake valve of the 2 cylinders, the exhaust valves of the 3 cylinders, the intake valves of the 4 cylinders, the exhaust valves of the 5 cylinders, these valves are absolutely closed. Then turn the crankshaft 360 degrees, find the compression top dead center of the 6 cylinders according to this method, and adjust the rest of the valves.

Most of the engines that come out now do not need to adjust the valves, all of them are hydraulically self-adjusting, and rarely use manual adjustment of the valves, and the easiest way is to turn the crankshaft to the top dead center, which is either a cylinder or a four-cylinder. If it is a cylinder, then adjust the intake and exhaust valves of one cylinder, the exhaust valve of one cylinder, the exhaust of four cylinders, and the intake of two cylinders according to the ignition order (e.g., 1-3-4-2).

Then the crankshaft turns around and the rest is done. You just need to remember a mantra (double rows do not enter), according to the ignition order, no matter how many cylinders the engine can be tuned twice.

Measure the valve clearance, the valve clearance is divided into cold and hot value, and the measurement should be carried out in accordance with the regulations of the car. Select the plug gauge that meets the specifications, insert it between the valve stem and the valve rocker arm (or cam), pull the plug gauge slightly, if there is a slight resistance, it means that the clearance is correct.

The advantages of diesel engines are high torque and good economic performance. The working process of a diesel engine has many similarities with a gasoline engine, and each working cycle also goes through four strokes: air intake, compression, work, and exhaust.

However, because the fuel used in diesel engine is diesel, its viscosity is greater than that of gasoline, it is not easy to evaporate, and its spontaneous ignition temperature is lower than that of gasoline, so the formation and ignition of combustible mixture are different from those of gasoline engine. The main difference is that the mixture in the cylinders of a diesel engine is compression-ignited, not ignited.

From the fan, the front end, the average engine is 1-3-4-2, and you can actually turn the crankshaft and look at the order in which the valves open, and you can get the firing order. Then use the legendary "double row does not enter the method" This method is simple The number of crankshafts that need to be rotated is the least, so the efficiency is the highest (double row does not enter double Both valves have to be adjusted on the exhaust valve Adjust the exhaust valve or not two do not need to be adjusted Just adjust the exhaust valve Use the feeler gauge In fact, the clearance of the adjustment is: intake valve exhaust valve 1 Turn the piston to turn the first cylinder to the top dead center, the first cylinder is calculated on the fan side The first cylinder, and then adjust the clearance of half of the valves according to the double row does not enter 2 The crankshaft rotates for a week, Adjust the last cylinder to the top dead center of the compression stroke, and still adjust the clearance of the remaining half of the valves in the double row Pure handmade watchtower master adopts If you don't understand, you can continue to ask me.

At the top dead center of the compression of one cylinder, adjust 1246, and then turn to the top dead center of the compression of the four cylinders, and adjust the top dead center of the four cylinders, and adjust to 3578.

How much clearance is generally adjusted for a 4-cylinder diesel engine.

1. When the top dead center of the compression of 1 cylinder (8120F is 5 cylinders) is found, according to the expression method, for the adjustable valve, plug the end of the valve stem and the head of the valve rocker arm with a feeler gauge, so that the feeler gauge moves back and forth, and gently blocks it, otherwise, it needs to be adjusted.

2. The specific adjustment method is: first loosen the lock nut on the rocker arm slightly, and then turn the adjustment screw with a screwdriver as needed, the lower (right) clearance becomes smaller, and the upper (left) clearance becomes larger, until the rocker arm and the valve are in contact with the thickness gauge and can still move, and then the screwdriver will be used to adjust the screw, tighten the lock nut, and then move the thickness gauge and rotate the crankshaft to re-check until the valve clearance values are all correct.

You can use the valve clearance two adjustment method, that is, turn the crankshaft twice to complete all the valve clearance adjustment, such as the work sequence is the 4-cylinder engine, open the cylinder cover head, rotate the crankshaft, see the 4-cylinder valve movement, when the intake and exhaust valves have overlapping movements, it is the exhaust top dead center of the 4 cylinders, at this time the 1 cylinder is in the compression top dead center, you can adjust the intake and exhaust valves of the 1 cylinder, the intake valve of the 2 cylinders, the exhaust valves of the 3 cylinders, these valves are absolutely closed. Then rotate the crankshaft 360 degrees, find the compression top dead center of the 4 cylinders according to this method, and adjust the rest of the valves. When adjusting, while tightening the adjustment screw, insert the valve stem end with a thick gauge and pull back and forth between the rocker arm to feel a slight resistance, and then check again until it fits.

This is the simplest and most practical method, and generally multi-cylinder machines can adjust all the valves in two times. In the 4-cylinder engine (1-3-4-2 work sequence), when adjusting the top dead center of 1-cylinder compression, 1 double, 2 intake, 3 rows, 4 no, the valve is absolutely closed: the valve clearance can be adjusted (1 cylinder) The compression stroke is over, and the power stroke starts [intake valve closing] [exhaust valve closing] Dual valve adjustable (2 cylinders) power stroke is finished, and the exhaust stroke starts (exhaust opens early) [intake valve close] Intake valve adjustable (3 cylinders) intake stroke ends, compression stroke begins (intake air closes late) [exhaust valve close] The exhaust valve is adjustable (4-cylinder) and the exhaust stroke is not adjustable, and the intake stroke starts (intake opens early) (exhaust opens late) are not adjustable.

I have been doing diesel engines for 6 years, and there are two ways to adjust the valve clearance: 1. Single-cylinder adjustment, the cylinder disc that needs to be adjusted is turned to the top dead center (TDC) of the cylinder's compression stroke, and the intake and exhaust valve clearances of the cylinder are adjusted respectively, and then the next cylinder is adjusted according to the firing order until all are adjusted. (Sometimes to determine whether it is the top dead center of the compression stroke, you can look at the fuel injection timing, the first few degrees of fuel injection before the top dead center of the compression stroke) 2, the two adjustment method upstairs said.

But we and my peers are using the monotonous method, which is adjusted in order of firing, so that it is not easy to make mistakes. The order of firing is different, and the order of the two adjustment methods is different, which is too troublesome and too easy to make mistakes, so we don't use this method. Tune in mind one principle when tuning:

It's better to be big than small. The valve gap should be slightly larger, and it should not be too small, otherwise it is easy to burn the valve.

The flywheel turns to the top dead center, that is, the flywheel mark coincides with the mark on the fuel tank, rotate the flywheel back and forth at a small distance, and at the same time see if the two valve pushers are moving, if it does not move, put the mark right, adjust the two rocker arm adjustment screws respectively, and adjust the intake valve and exhaust valve adjustment 0,40

Take the four-cylinder engine with ignition sequence of 1-3-4-2 as an example, when the first cylinder is located at the top dead center of the compression stroke, then there are: 1 cylinder "inlet and row are evenly closed" (compression top dead center cylinder "row off, inlet open" (intake bottom dead center cylinder "inlet and row are evenly open" (exhaust top dead center cylinder "row open, intake" (work top dead center) When the 4th cylinder is located at the top dead center of compression stroke, the working conditions of each cylinder can be deduced and adjusted by analogy.

When the engine is working, the valves will expand due to the increase in temperature. If there is no gap between the valve and its transmission parts in the cold state or the gap is too small, then in the hot state, the thermal expansion of the valve and its transmission parts will inevitably cause the valve to close loosely, resulting in the engine leakage in the compression stroke and power stroke, so that the power decreases, and it is even difficult to start in serious cases. In order to eliminate this phenomenon, a certain gap is usually left in the valve and its transmission mechanism when the engine is assembled in the cold state to compensate for the expansion of the valve after heating.

This clearance is called the valve clearance.

4-cylinder valve clearance adjustment method and formula: When adjusting the valve clearance of 4-cylinder or 6-cylinder engine, the valve adjustment sequence of different engines is often different because the valve adjustment sequence is related to the working sequence of the engine and the position of the intake and exhaust valves, so that the misalignment phenomenon is often caused by mixing in the operation. To find a concise and easy-to-remember approach, we combined teaching production practices.

Summed up a four-stroke mantra for the 4-stroke engine with "double, row, no, in".

Photo by Q&A) Xingrui Ideal One Model Y Model X Hiphi X Leap T03 @2019