Carter piston, caterpillar, caterpillar xuzhou, carter, the engineering machinery spare parts, four matching engine,
Piston top valve is going on, what reason is caused, how repair?
Screw valve clearance adjustable gap is too small, when the piston reaches the top dead center is still not closed and the collision;
Also could be the problems in the distribution system, such as timing belt jump tooth, the engine valve timing error, is also the kind of problem will happen.
To professional service place is better.
The engine is working, the valve will be inflation due to the rise of temperature.
If under cold state between the valve and its transmission is too small, no gap or clearance is under hot condition, the thermal expansion of the valve and transmission parts is bound to cause valve closed lax, causes the engine air leakage in the compression stroke and power stroke, so that the power drop, serious when even is not easy to start.
In order to eliminate this kind of phenomenon, often in a cold engine assembly, with a certain gap in the valve and actuator, to compensate for the expansion of the valve after heated.
This gap is called valve clearance.
The cause of the valve impact piston has several?
1 to replace cylinder head is not after the replacement of cylinder head valve clearance is not adjustable valve clearance, with gas phase aberration, piston by the next check point check point upward movement, arrived at top dead center, the inlet valve or the exhaust valve in large open state, can appear the piston against the phenomenon of valve.
2 valve clearance adjustment improper valve clearance, not gap is smaller, less noise, inlet and exhaust more fully.
If the valve clearance adjustment is too small, engine working time heat expansion, rocker arm bumped head top to open the valve, the valve cannot be returned to in situ, caused by the piston valve head top surface collision.
Valve stuck inside the valve guide adverse or oil when the engine combustion time too late, the engine temperature, the exhaust valve is often out of flame flow of high temperature burning, dry friction in the valve stem and valve guide, and the bad lubrication condition at this time, for a long time and cause the valve stuck inside the valve guide, valve against the pistons occur.
Gas lock disassembling chaos or wear serious air lock is usually used in pairs.
So when the maintenance should be installed in accordance with the requirements of the original assembly lock plate, matching use arbitrarily, more new and old lock plate must not be mixed use, otherwise it will make the valve head uneven, cause valve fracture or lock out;
Second, when gas lock serious wear and tear, lock plate is also automatically jump out, lead to valve piston impact.
Valve spring break or stretch less than some drivers to & other;
DORA run & throughout;
, any change of engine speed, resulting in greatly increases the frequency of the valve spring compression and extension, leading to spring fatigue fracture;
Some valve spring force is weak, the engine at high speed, spring can't return quickly, lock out, valve sink into the cylinders.
Valve guide or rocker arm bushing wear serious worn valve guide, in work, easy to make the valve rod tilt in the valve guide, until the valve rod break off and fall into the cylinders;
Valve subsidence quantity does not conform to the requirements in some drivers when replace valve, valve seat ring, ignore the subsidence check valve, the subsidence value is too small, lead to valve against the pistons.
If the timing gear rolling key engine valve timing gear slotting serious wear and tear, and failed to timely repair, so, when the engine idle speed running, the key is in middle position, or phase has no obvious change;
When sudden acceleration, deceleration, or engine speed changes frequently, under the effect of inertia force of the camshaft with gas, the key in the slot glide, between the camshaft timing gear and the camshaft with kuang, cause with gas phase change, leading to the door the impact piston.
The purpose of the relief agency improper adjustment decompression is to make the engine start easily.
Because the engine compression is high, so the piston to the check point on the top and the bottom of the cylinder head plane distance is very small.
So if the relief agency improper adjustment, is likely to lead to valve impact piston.>>>
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