Advice 1: How to check the tightness of the valves

The engine starts to warm up, "do not pull". The cause of this may be the wear of the piston system, a malfunction in the ignition system or timing. Namely, the loss of integrity of one or more valves.
How to check the tightness of the valves
First of all, you need to make sure that this trouble is to blame the gas distribution mechanism. To do this, remove the valves from the cylinder head. Before removing, make their marks as after inspection and repair, each of them needs to go back to his place.
Thoroughly clean the valve seat and the surface of the head around the valve face. Carefully inspect the cleaned surfaces. In the case that you will find at least one of the following fault recovery is not possible, and these details will need to be replaced:

• cracks, vicoli in the saddle;

• defects on the working surface of the valve burnouts;

• wear beyond the permissible limits.
After faulty parts are replaced, perform the lapping the valves and seats, followed by check their integrity (with the valve closed should not pass exhaust gases).
The procedure for lapping the following: the valve install soft spring in such a way that between the saddle and the plate remains a gap. When you press on the valve until it contacts with the saddle it should be easy to clean.
On the saddle apply a thin layer of polishing paste and turn the valve left/right 180 degrees. At the end of the turn valve is lifted by the spring, and to return it you need to "slap" against the saddle. So spend grinding the working surfaces. At home, it is better to do by means of rotation, in the extreme part of which is wearing a rubber suction Cup.
Control the lapping process visually. After the valve face formed matte rim width more than 1.5 mm, the grinding is finished.
Install the valve into place. The quality of the work performed, check the old tried and tested method: pour under valve kerosene and in 5 minutes, see if he passes through the valve.
If no leaks, then the work carried out efficiently and the extra effort from you is required. If the kerosene leaks, then operation with the grinding of the valve must be repeated.
Useful advice
To ensure that the lapping process does not cause a wear of the guide bushing, lubricate it with engine oil.

Advice 2 : How to check grinding valves

The comfort and safety of vehicle operation depends on how well it is running naturally aspirated. Important role to play intake and exhaust valves, which should be as tightly against its seat, located on the cylinder head. Valves must be absolutely tight. Only at observance of these conditions in the combustion chamber will create pressure needed for proper operation.
How to check grinding valves
You will need
  • - a set of flat probes;
  • - special pattern or fitting a wide range;
  • - paste for lapping;
  • device for lapping valves.
In order to verify tightness of valves, remove the cylinder head (cylinder head), then clean it and the bearing housings, in which often accumulates soot and dirt. Also remove any deposits of oil and using a metal brush, clean the carbon deposits from the walls of the combustion chambers.
Inspect the cylinder head and bearing housing to ensure no cracking. Also check the camshafts, the bearing holes of hydrotalcite and bearing for signs of covering metal. Note how tightly the guides and valve seats sit in the cylinder head. Make sure that there are no traces of displacement when running naturally aspirated. Check valve and seat on the absence of traces of burning and cracks.
Using a special pattern, check flatness of cylinder head. If such a template is missing, use a wide metal ruler and check the lower mating plane of the head.
To check flatness, place a ruler to the plane of the head. Make sure that between its edge and the plane, with no gaps. Inspect the entire plane, since the gaps can be in the middle and at the edges. The gap should not be more than 0.01 mm. If it is greater than this value, the mating plane of the head will need to progressirovanii or replaced. To change the cylinder head must, together with the bearing housing.
Also check the head for leaks. To do this, close the window coolant to the thermostat from the face surface of the head, and then cut from a piece of rubber gasket and place it under the elbow of the thermostat. Then flip the head and fill it with kerosene all the internal cavities designed for coolant.
Valves also need to be checked tightness. To make it easy. To do this, put the head unit on a level surface so that its mating surface is facing up. Then pour in the combustion chamber the kerosene and wait a few minutes. The decrease in the level of kerosene in one of the cells means that one or both valves are leaking.
Inspect the cylinder head for leaks. If leaks or sinks found on the mating plane of the head, to repair it will be possible only with the use of cold welding. If desired, it can be replaced.
Elimination of leakage of valves can be made by lapping. But this method can be applied only in the case if the seat and the valve plate has no cracks, ruts and other mechanical damage.
Is the advice useful?