Valve clearances should be adjusted to increase engine life. It is possible not to do this only on vehicles with hydraulic lifters. They monitor the required parameters in real time and make adjustments.
Any car has two valves per cylinder. One launches a hot mixture, while the other releases exhaust gases. The system that drives this mechanism is called the gas distribution system. After the motor is heated, the parts expand. Therefore, on a cold unit, there must be gaps between some elements.
If the valves are poorly adjusted, this causes:
- decrease in engine efficiency;
- reduction of its service life;
- the need to visit the service center more often.
If the gaps are small, their seats may burn. If too large, the valves open only partially, which negatively affects the engine power. With correctly set gaps during heating, the parameters are reduced to minimum values. This ensures the adjustment of the gas distribution phases and their longer service life.
If there are no devices in the car that allow you to track the required clearance, you need to be prepared for the fact that every 30-35 thousand kilometers you will have to check this parameter yourself. This is especially true for domestic cars. On foreign cars, the need may appear after 60-80 thousand km. mileage. This is due to the fact that engines of such vehicles have a longer resource, and the clearances themselves are kept more stable.
Measurement
Determination of the size of the clearances is possible only on a cold engine. For the operation, you need to prepare:
- probe;
- open-end wrench;
- micrometer;
- other tools selected depending on the category of the pusher.
To measure the thermal gap, you need to turn the crankshaft so that the cam is directed in the opposite direction. For this purpose, you can hit it a little with a hammer and swing your hands. Using a feeler gauge, the gap between the valve and the tappet is measured. The data obtained must be verified with the values specified in the instructions for the car.
To measure parameters on an engine with washer adjustment, the crankshaft is rotated so that the cam is pointing up. The rest of the steps are the same. If, as a result of diagnostics, it becomes clear that the readings are rejected, adjustment will be required. Please note: the value for the inlet and outlet valve is different. This is due to the different heating temperatures. Work should be done on all cylinders.
It is recommended to check the tension of the toothed belt of the drive before adjustment. The indicator itself does not affect the size of the gaps. However, a loose tightening, stripped threads can cause insufficiently rigid attachment of the housing to the block head. Because of this, the clearances will change depending on the belt tension.
Adjustment tools
Typically, valve adjustment is carried out using probes. In the standard set, they are available in different sizes from 0.05 to 1.00 mm. they go with increasing thickness. For some types of vehicles, special probes are produced, which are sold one at a time.
You can also perform manipulations using the arrow indicator. In this case, the adjustment is more accurate, since the indicator "catches" the gap more accurately. Auto shops sell sets with indicators for different engines. You can make a device with your own hands.
For ease of use, a tool for installing and removing shims may be useful. There are special varieties for Ford, Toyota and other engines that have shims.
Adjustment with a dipstick
First, preparation is carried out:
- Disconnect tubes, covers, cables, dismantle the air filter.
- Unscrew the spark plugs to make the crankshaft turn more easily.
- Remove two nuts and cover, remove oil residues.
- Remove the timing belt cover.
The process starts from the piston of the cylinder. It is exposed to the high point of compression. For more accurate work, you should be guided by the marks set by the manufacturer.
Turn the crankshaft in a sprocket strictly clockwise. For the best option, make sure that the risks on the bearing housing and the crankshaft completely coincide. On the screw used to set the gap, the locknut is squeezed out. The gap should be set so that the flat feeler is the maximum of the bolt turn. When the locknut is tightened, the readings are checked for correctness. Remember that tightening too much may cause them to move. The same steps are repeated with all other valves.
Setting the gap according to the optimal parameters may not work right away. This is due to the fact that after tightening the locknut, it gets a little lost. Therefore, a correction should be made by increasing the parameter.
Rack and indicator adjustment
Using this approach allows you to achieve maximum accuracy. The vehicle must be parked on a level surface. First, preparatory work and the removal of valve covers are carried out. Thereafter:
scroll until the marks on the camshaft gear coincide with the marks on the body;
- with a marker on the gear, put your designations every 90 degrees;
- fix the rail with three bolts;
- put down the dial indicator.
Make sure that the scale on the latter is at zero. Using a special device, pull the cam up. The indicator hand should move approximately 50 divisions. If necessary, adjustments are made in the same way as using a dipstick. If there is a discrepancy, take a 17 key and loosen the lock nut. Then adjust the gap with the most suitable wrench. After checking, the locknut is tightened, the clearance is re-checked.
When all the manipulations are completed, start the engine and listen to its operation in different modes. If the above methods have been applied after rebuilding the head, make sure the valves are properly lapped in.
Features of work on different car models
For rear-wheel drive VAZ vehicles, a 0.15 mm dipstick is used. The exception is engine models with installed hydraulic expansion joints. In them, the gap is selected automatically, so checking it and adjusting it is not required. For a warmed-up engine, the gap is set with a 0, 20 mm dipstick. This is done using adjusting bolts, which are fixed in the desired position with locknuts.
On front-wheel drive VAZ cars, adjustment is made by selecting the thickness of the adjusting washers. There are elements with different sizes. However, with parameters of 2, 5 and 2, 8 mm are needed in a situation of wear of the seat in the cylinder head.
For Ford, RK can be produced both with adjusting washers and screws. The latter are often needed for older models. For Ford, as for Honda, adjusting the valve with screws is easier and faster, but in this case, such work will have to be done more often.
Check the parameters regularly. This will provide:
- stability of the internal combustion engine;
- long service life;
- maintaining good condition of valves and pistons.
Unregulated valves are more likely to deform, which leads to an increase in clearance. If there is a long time on such an engine, then the valve will simply burn out. With a long stroke of the engine piston, a collision of these two elements can occur. Because of this, more expensive motor repairs will be required.
Experts say smaller or larger washers are discouraged. As a last resort, the usual permutation of these elements can help. They are heavily loaded, so the initial non-compliance with the parameters can lead to accelerated wear and engine malfunction.
