Common Failures of A Turbo and How to solve them ?
1 、Oil leaking
Main causes：Oil contamination, solid particles are seriously polluted ; improper lubrication oil, use poor quality or low grade oil; lack of oil or low oil pressure; unsmooth oil return; Excessive pressure at oil inlet; The air filter is plugged lead to unbalanced of the pressure on both sides of the compressor ; The diesel engine idle running long time, oil seal at a certain negative pressure.
Solutions : first check the speed of diesel engine , if the diesel engine idle running time is too long, should increase the speed; If the inlet oil pressure of the turbocharger is too high or too low, the amount of oil should be checked. If necessary, qualified oil should be added or replaced.; If the oil pressure display is normal, check whether the oil return channel of the turbocharger is unblocked ; Dredge and clean the diesel engine crankcase ventilator; Clean the air filter and check the inlet pipe connection seal; Check whether the rotor is stuck during rotation, and it is normal to rotate more than 2~3 circle by inertia. Meanwhile, check whether the exhaust turbine and compressor wheel collide with the housing during rotation; The axial momentum of the rotor and the radial clearance of the shaft at the flange of the compressor wheel are respectively measured by the percentage meter and the plug gauge. If the clearance does not meet the requirements, the turbocharger must be disassembled for maintenance.
Main causes : high speed diesel engine suddenly emergency shut down or unload; The filter element of air filter is seriously blocked, the inlet rubber tube is seriously aging or is sucked flat, etc. The inlet of the compressor is not smooth, and there is too much sludge in the inlet pipe and turbine outlet channel, which makes the inlet resistance increase. A diesel engine is equipped with two turbochargers and shares one intake manifold. When one cylinder of the diesel engine is not working well, it causes the compressor to surge. More carbon is accumulated in the turbine, bearing wear, turbine or wheel blade deformation, friction between rotor and housing etc. The carbon accumulated in the exhaust pipe is blocked, which causes the turbine exhaust obstructed and the exhaust resistance increases.
Solutions: operate the diesel engine correctly and idle for 3 to 5 minutes before shutting down. Check whether the air filter is blocked. If it is blocked, clean or replace the filter element. Check the inlet hose and replace it if serious aging or absorption is found. Check and dredge the exhaust pipe; Remove the carbon accumulated in the turbine blade, rotating shaft, sealing ring and other parts, check whether the blade is deformed or damaged, check the axial and radial clearance of the rotor, and conduct dynamic balance test if necessary.
3、High exhaust temperatures
Main causes are: bad lubrication of the turbocharger, insufficient oil pressure, high temperature or insufficient oil supply, lead to the heat taken away by the oil is reduced; Fuel system failures, such as injection delay, excessive oil supply, oil injector drops or the exhaust valve leakage, etc., can lead to exhaust temperature is too high, and then make the turbine inlet vane damage deformation, as well as the turbine end bearing local overheating; The oil and gas seal rings at the turbine end are damaged, and the high temperature exhaust gas enters the compressor cavity, which increases the temperature of the turbocharger. The floating bearing is badly worn or damaged, the rotor assembly loses its dynamic balance, and the rotor friction with the housing, causing the turbocharger to overheat.
Solution: To check the injection quality oil, compression ratio and cooling system of the diesel engine at regular oil supply and injection time to ensure that the diesel engine does not overheat under rated operating conditions. Check whether the oil supply of the turbocharger is normal, and the oil supply pressure of the supercharger should be 0.2-0.4mpa. Check whether the internal parts of the turbocharger are damaged, handle or replace the damaged parts as appropriate.
Main causes: due to the bad connection or sealing of the inlet and outlet of the turbocharger, leakage noise is generated. If there is foreign object entering, it will cause damage to turbine or compressor wheel blades, and the change of gas movement in the work will make the supercharger vibrate strongly and generate high frequency noise. Rotor shaft serious wear, floating bearing clearance is too large or bearing damage, turbine rotor carbon deposit, the rotor shaft axis trajectory change, rotor shaft vibration, loss of dynamic balance, noise.
Solutions: check whether the air filter is blocked, compressor inlet pipe or in the compressor casing and whether there is foreign object in the diesel engine exhaust system, diesel engine intake or exhaust pipe is loose, as appropriate to clean or tighten. If sound is obvious metal grinding, shall check the lubrication of the turbocharger are in good condition, whether bearing loose , whether the blade deformation, impeller and housing are friction, impeller and housing are sticky oil sludge, radial and axial clearance is overrun, act accordingly. If the turbocharger vibration strongly, it is by the unbalance of the rotor shaft assembly or floating bearing damage caused by, should break down the turbocharger, check if there is a foreign object or its internal parts damaged, as processing or to change.
What is good for a turbocharger?
The turbocharger is designed such that it will usually last as long as the engine. It does not require any special maintenance; and inspection is limited to a few periodic checks.
To ensure that the turbocharger's lifetime corresponds to that of the engine, the following engine manufacturer's service instructions must be strictly observed:
· Oil change intervals
· Oil filter system maintenance
· Oil pressure control
· Air filter system maintenance
What is bad for a turbocharger?
90 % of all turbocharger failures are due to the following causes:
· Penetration of foreign bodies into the turbine or the compressor
· Dirt in the oil
· Inadequate oil supply (oil pressure/filter system)
· High exhaust gas temperatures (ignition system/injection system)
These failures can be avoided by regular maintenance. When maintaining the air filter system, for example, care should be taken that no tramp material gets into the turbocharger.
If the engine does not operate properly, one should not assume that the turbocharger is the cause of failure. It often happens that fully functioning turbochargers are replaced even though the failure does not lie here, but with the engine.
Only after all these points have been checked should one check the turbocharger for faults. Since the turbocharger components are manufactured on high-precision machines to close tolerances and the wheels rotate up to 300,000 rpm, turbochargers should be inspected by qualified specialists only.