Deutz diesel engine FAQ
7. Why does the valve break?
After the valve is broken, the valve head will fall into the cylinder, causing the cylinder head and piston to be broken. If the engine is not stopped in time, it will seriously cause deformation and damage to the connecting rod, crankshaft, etc.
There are many factors causing valve breakage. In addition to the material and heat treatment problems of the valve itself, there are also the following reasons:
(1) The valve clearance is incorrect;
(2) The timing gear has the wrong marking or is not assembled according to the marking, and the valve phase is incorrect;
(3) The exhaust temperature is too high;
(4) The valve spring is broken;
(5) The valve lock clamp is not installed properly or one is missing;
(6) The camshaft gear pressure plate bolts are loose, causing the camshaft gear to move and the valve timing phase to be imbalanced;
(7) The Deutz diesel engine speed is too high and "speeds up", which increases the impact load on the valve and causes the valve to break;
(8) The disassembly and assembly of the valve lock clips are chaotic and do not match each other, which can easily cause the valve to fall off.
8. Why does the cylinder head crack?
After a crack occurs in the cylinder head, cooling water will enter the cylinder and be sprayed out from the exhaust pipe when the engine is working. The main factor causing cylinder head cracks is generally caused by uneven cooling and heating. The reasons are:
(1) The fuel supply time is wrong, the atomization of the fuel injector is poor, and the combustion deteriorates;
(2) In winter, the cooling water is not drained and freezes;
(3) After the water tank is short of water or the water is cut off, the engine generates high temperature and suddenly adds cold water to cause cracking;
(4) The oil supply volume of each cylinder of the high-pressure oil pump is uneven. If the oil supply volume of some cylinders is too large, cylinder head cracks will also occur.
(5) The water channel hole on the bottom surface of the cylinder head is cast out of alignment, the water channel hole is not cleaned cleanly, the water channel is too narrow or the corner is too small, and the cooling water circulation is not smooth;
(6) Due to unreasonable modification of supporting products, high temperatures may also cause cylinder head cracks.
9. Why does the cylinder liner break?
(1) The intrinsic quality of the cylinder liner does not meet the technical requirements, such as low hardness, high sulfur content, etc.;
(2) The tightening torque of the cylinder head bolts does not meet the specified requirements or the cylinder liner end face is lower than the cylinder block stop plane when assembled, so the cylinder floats when the piston moves up and down, causing the cylinder liner to break;
(3) When installing the cylinder liner, there are carbon deposits, iron filings and other debris in the cylinder block seam;
(4) The cylinder block hole is deformed due to long use, and the upper and lower parts are not concentric;
(5) There are cracks on the edges of the screw holes around the cylinder liner installed in the cylinder block. In this way, the head of the cylinder liner is squeezed and broken due to uneven thermal expansion during high-temperature operation of the engine;
(6) Painting the cylinder liner when assembling it will also cause the cylinder liner to break;
(7) The upper plane of the cylinder liner shoulder is too much higher than the upper plane of the body;
(8) The shoulder groove of the cylinder liner should be rounded. If there is no rounded corner or the rounded corner is too small during processing, it will cause stress concentration and easily cause the cylinder liner to break from the shoulder;
(9) Using an inferior cylinder bed may also cause the cylinder liner to break;
(10) The cylinder liner of the body is not level during processing, and the seam is not chamfered.
