Malfunction and Troubleshooting for Diesel Engine

Malfunction and Troubleshooting for Diesel Engine 1-Causes and Troubleshooting for the Engine Not Being  Started 

CAUSES It is cold Machine oil is viscous

Failure of fuel system Water mixed in the fuel The fuel get thickening and can’t flow Easily Air exists in fuel system Injection fuel is little or the spray is not excellent Incomplete combustion

Interrupted of diesel

TROUBLESHOOTING Fill machine oil into crankcase after warming-up. Fill machine oil into inlet pipe Remove the connection belt from the machine Start the engine and stop it when it is heating, assemble the belt and then restart the engine. Clean fuel tank, fuel filter and fuel pipe, then change the fuel. Use prescribed brand fuel

Emit the air, tighten each connect part to the fuel pipe Check the position of governing handle or check and clean the fuel nozzle, change the nozzle if  necessary. Mainly by ill spray Incorrect delivery angle Leakage in gasket of cylinder head Deficiency in pressure of compression Lack of oil, should fill fuel into the fuel

fuel

Deficiency in pressure of compression; Loosen in the nut of  cylinder head; Damage or leakage in the gasket of cylinder Big gap in the piston ring due to wear and Tear Leakage caused by each gap of piston ring lined in one direction Serious stickiness or breakage in piston ring Leakage in gas valves

Incorrect in valve clearance The valve stem is clipped in the guide pipe

tank. If have obstruction or leakage in the fuel pipe and fuel filter, drain out them with the air. Tighten the nut of cylinder head in the diagonal sequence; check the gasket of cylinder as per the standard requirement. When the engine with the new gasket is heating, tighten the nut of cylinder head again. Change the piston ring

Make each gap of piston at angle of 120

Clean it by diesel fuel or change the piston ring. Skive the gas valve, or send it to repair factory if the vestige is too deep. Adjust the gap as specified. Disassemble the gas valve, clean the stem and guide pipe with diesel fuel.

2-Causes and Troubleshooting for Deficient Power of  Diesel Engine CAUSES Malfunction of fuel system; Parts obstruction in fuel

TROUBLESHOOTING Check the fuel switch, they should be opened fully. Clean the fuel filter and fuel pipe.

filter and fuel pipe; Inadequate fuel supplying; Bad pressing of fuel pump Malfunction of the fuel nozzle; Incorrect injection pressure Carbon deposit in the nozzle hole Needle was bit Loose fit between needle and needle body Obstruction in air filter   Not fast enough of engine speed

Check or change the damaged parts of  fuel pump. Adjust the injection pressure

Clean Clean or change Change Remove, clean or change the filter core. Check the speed of engine with the tachometer, and then readjust the speed limit bolt.

3-Causes and Troubleshooting for Engine Stopping  Automatically  CAUSES

TROUBLESHOOTING

Malfunction of the fuel system Run out of fuel Obstruction in fuel pip or air  filter  Air exists in fuel system  Nozzle needle was bitted Obstruction in air filter 

Fill fuel.

Sudden increase of load

Check or clean. Emit the air. Clean, skive the nozzle or change it if necessary. Check, clean or brush off, or change the filter  element Lighten the load.

4-Causes and Troubleshooting for Exhaust with Black  Smoke CAUSES

TROUBLESHOOTING

Overload

Lighten the load; change the matched machine if  it does not comply with the requirements. Check injection pressure and spray condition and remedy; change the nozzle if it was damaged. Clean the air filter; check the cause of leakage and remedy.

Bad spray

Lack of air or leakage

5 - Causes and Troubleshooting for Exhaust with Blue Smoke CAUSES

TROUBLESHOOTING

Machine oil mixed in cylinder  Piston ring is clipped, worn or lack of elasticity, hatch of  each ring turned to the same direction and make engine oil up Big gap between piston and cylinder  Wear and tear of valve and guide

Check the oil level, drain off the redundant engine oil Check and replace the piston ring, and cross hatch of each ring

Check and replace the piston ring, and cross hatch of each ring Change

6-Causes and Troubleshooting for Exhaust with White Smoke CAUSES

TROUBLESHOOTING

Water mixed in diesel fuel

Clean the fuel tank and filter and change the diesel fuel.

7-Checking Methods when the Engine Encounters  Malfunction  CAUSES

TROUBLESHOOTING

Speed sometimes fast, sometimes slow

Check if the speed governing system is flexible, and if air mixed in oil pipeline. Check fuel system, especially the nozzle.

Abnormal noise suddenly sent out Exhaust with black suddenly Check fuel system, especially the nozzle. Rhythmically metal knocking The fuel delivery angle is too big, should adjust sound in the the angle. cylinder 

DIESEL ENGINE FAULT DIAGNOSIS Most diesel engine faults are due to problems in one of three areas: 1. Fuel supply 2. Electrical / electronic 3. Air supply 4. Mechanical components (pcv, egr, turbo control mechanism) Rarely these days is there a major mechanical cause such as head gasket, broken crankshaft etc. It is also a fact that the expensive items such as the injection pump and turbo are very reliable and should ONLY BE CHANGED WHEN ALL OTHER CAUSES HAVE BEEN ELIMINATED.

1 )FUEL SUPPLY : Engine stops minutes or miles after refueling: This is becoming quite common due to increases in the biodiesel content of fuel (up to 15% is now a requirement). Biodiesel is a g ood solvent and dissolves the gunge lining the fuel tank and fuel lines leading to blockage of the fuel filter. Some can get through this and clog and damage the injection pump and injectors. We checked our 4year old Vectra’s new filter after 5k

miles and it looked like a dirty oil filter.....The older your vehicle the more gunge there will be to dissolve...Once clean, you should have no further problems, but you may have to change the fuel filter several times at monthly intervals.

Engine stops on a motorway jo urney even though the fuel gauge shows  pl en ty of fu el : This is due to failure of the in-tank pump. The engine may have been relying on the under bonnet one for some time and this will soon fail or may have just failed. The tank is a saddle tank and relies on the in-tank pump to also keep the levels in each half the same. When it fails, the under bonnet pump draws fuel from one side until its empty, but the gauge, because it has a sensor in each side, mis reads. (The problem never shows up on normal roads due to cornering sloshing the fuel from side to side and keeping the levels about equal.)

Engine been running fine until stopped then won’t restart or only restarts when cold : Most likely due to either the cam sensor or injector leak back. Try cooling the cam sensor with some frozen food ( it’s the one near the oil filler cap). Check for leak back - it’s quite

common on older or high mileage vehicles and injec tor flow & leak back test kits are widely available from Laser & Draper, though not essential. If the engine starts when towed, then it’s

almost certainly injector leak back

Starting is taking more cranking than usual , especially when the engine is hot : Suggests the in-tank pump has failed. Must be replaced a sap or the under bonnet one will also fail and the engine will never start or will stop dead. (Could also be due the c am sensor or injector leak back.)

Engine starts okay but performance is poor or erratic , someti me it seems to be in some sort of limp and won’t go over 70mph,may also be unstable: This is often a fuel rail pressure se nsor or regulator problem. Land rover Technical bulletin LR0052 documents a problem caused by water ingress into the wiring loom between ecu and fuel pressure sensor on t he TD4. This corrodes the sensor contacts and damages it, causing the above symptoms as well as poor idle (look at the connectors for signs of moisture and corrosion). Disturbing the connections to fit a tuning box can produce the symptoms falsely leading you to blame the box. If the regulator (the 2 wire circular object bolted onto the end of  the injection pump) is sticking or worn, the engine may also cut out. (Failure to reach the expected pressure leads the ecu to stop the engine in case its due to a major fuel leak)

Engine starts okay but performance below 2000rpm is boor but ab ove this is fine: Weak maf sensor signal .Disconnect the maf plug and if low down torque is much better, this confirms it.

Engine performance is fine or very good, but fuel consumption has dropped  and there is more exhaust smoke and a sooty deposit on the rear bumper :

The maf sensor is producing too high a signal and over fuelling the engine. If  this occurs at idle as well, the exhaust will smell of diesel and be unstable. The engine can even stall as soon as you touch the accelerator if the signal is far too high.

2) ELECRICAL PROBLEMS: These usually take the form of out of spec or faulty sensors, apart from the water  ingress issue on the Freelander Td4 , mentioned in the previous section. Cam sensor:

Only used during starting but can fail, especially when hot. Quite common. Crank sensor: if erratic will affect the timing and cause performance problems. Not very common.

Maf sensor: sooner or later EVERY vehicle will suffer from problems due to the maf sensor under or over fuelling the engine. Under fuelling manifests as poor or very poor performance below 2000rpm, a drop in mpg, possible hesitation & vibes felt through the steering wheel at about 1800rpm. Autos can stall and pulling out of turning or on to roundabouts is nerve wracking until the rpm reaches 2000 and then you shoot off a high speed! Over fuelling shows up as poor or very poor mpg, rich flat spot - nothing happens, then there’s puff of smoke and off she goes, otherwise performance & flexibility can be good - too good in fact! Checkout our website fo r the Synergy 2.

Map sensor: This rarely fails but can become blocked and this can reduce the performance. If the ecu ‘sees’ a low signal it will not incre ase the fuelling. Low pressure fuel sensor: its on the fuel filter housing. If the low side pressure is down the engine warning light will stay on and the engine may not start or may cut out as soon as significant power is required. A clogged fuel filter and/or failure of one or both electric pumps is usually indicated..

Fuel rail pressure sensor: This can produce a wide range of performance related symptoms if faulty. If dead, or if  it has become disconnected, the engine may start but there will be little power - max speed will be 70ish and you’ll be down to 30mph or less on hills. See previous section for the known TD4 water ingress problem.

3) AIR SUPPLY PROBLEMS: Lack of air can show up as smoke from the exhaust but in some cases, if boost pressure is down due to a major air leak then the resulting low map se nsor signal stops the ecu from increasing the fuel. So no smoke, but no power either.

75/ZT: Usually only leaking seals at the intercooler inlet & outlet and occasionally a split in an intercooler hose produce any problems on these vehicles. However it worth removing the map sensor and cleaning it. (requires inlet manifold removal) as a last resort.

Freelander TD4: As above and, since the TD4 has a variable geometry turbo, there is more to go wrong. Often the symptom shows up engine warning light illumination and a loss of power at a steady speed (50mph+), whereas no problems occur in town. This is due to the variable geometry mechanism not working properly. Check the thin tubes from the brake servo line to the solenoid and thence to the actuator capsule. Also check the actuator and make sure the mechanism on the turbo has not seized up. (with the engine idling, connect the solenoid directly to the battery - the actuator and mechanism should move.)

Clogged catalyst: Not common but not unheard of - obstructs the exhaust flow and this affects the tur bo which may then not produce the re quired boost pressure.

4)MECHANICAL COMPONENTS THE PCV: crankcase ventilation valve should be changed every 60Kmiles /100 k km. In extreme cases blockage increases crankcase pressure so much that oil is forced out of t he dipstick and past the oil seals. The exhaust can emit blue smoke as a consequence, leading some dealers to tell you that the turbo has failed! Otherwise excessive crankcase fumes entering the engine increase exhaust smoke & reduce performance since they replace the intake air.

THE EGR VALVE : This should be cleaned at the above intervals and if c logged will obstruct the air flow into the engine, producing Smokey exhaust and loss of power. Ditto if the valve jams open.

INJECTORS: These should be serviced once 100k miles o r 5years has passed unless the engine is running perfectly. They suffer from several conditions: Leakback - (starting problems) clogged / worn nozzles - (poor spray pattern = knocking & poor mpg, white smoke), worn / sticking valving - (poor atomisation & dribbling = white smoke, knocking, poor mpg ). Just cleaning them is no use at all. They should be stripped down and parts replaced and then all balanced as a set. This will give much smoother running and improved mpg. We recommend lynxdiesels.com for this job.

INJECTION PUMP: This is most likely to be damaged by acc idental fuelling with petrol, as will the injectors. Even if there was no apparent ill effects at the time, its possible that the life expectancy of them will have been drastically reduced.

TURBO: Very reliable and any blue exhaust smoke is probably due to a clogged pcv valve so make sure you replace this BEFORE THE TURBO! On t he TD4, confirm the vnt mechanism is working before condemning the turbo.

PREVENTATIVE MAINTENANCE TIPS: These are our personal recommendations for reliable motoring and we practice what we preach. In 30years of motoring we’ ve never broken down nor had major component failure.

Nothing can stop some parts from wearing out - the maf sensor and electric fuel pumps, for example but we’re convinced you can prolong the life of the others and save yourself a lot of  hassle & expense for little outlay.



Change the PCV valve



Clean the EGR valve



Change the oil and all filters twice as often.



Avoid supermarket fuels. (or if you must use t hem add Millers)



Use Millers Ecomax diesel additive. Visit Millersoils.net for a stockist



Use ZX1 in the oil (also goes in the fuel, power stee ring and transmission)