QUICK BUYING GUIDE
When viewing a used diesel engined vehicle ensure you are present when the engine starts from cold. Diesels are always a little clattery and smokey first thing in the morning but this should
disappear in around 5 minutes.
Check for any fuel leaks, some are cheap to rectify, some are not!
Ensure you have the cam belt (if fitted) changed after purchase, even if it has been changed not too long ago. Broken cam belts can result in mega repair bills.
Over the years we have had the opportunity to test various engine oils on many vehicles.
Fully synthetic oils are 'pushed' as the ultimate choice but we beg to differ.
Fully synthetic oils are too 'thin', this results in oil leaking past valve stem seals and past turbo seals resulting in blue smoke at start up and oil in inlet/boost pipes.
We personally use and advise that a semi-synthetic oil is used with a rating of either 10/40 or 15/40, these oils are more viscous and are less likely to weep past seals. These oils also deaden engine 'tapping and ticking' sounds.
We have yet to decide the best oil, but will add this info at a later date.
Click here for more information on Engine Oil.
A clogged or partially clogged air filter will create an all manner of problems such as power loss, black smoke, reduced mpg figures, failure of the MOT smoke test. It is imperative that the air filter is renewed at the recommended service intervals and more often than recommended if the vehicle is used in dusty conditions (not normally a problem in the UK!).
We strongly recommend using either a genuine replacement filter or one from a reputable manufacturer, like everything these days dirt cheap parts are available but cost cutting engine parts is false economy.
Also, blowing out the air filter with an air line really is not a good idea.
EGR (Exhaust Gas Recirculation) systems where added to the diesel engine to reduce exhaust emissions when the engine is idling or under partial load. Exhaust gas is dumped back (via a valve arrangement) into the inlet manifold where it is again 're-burnt' and in theory cleans the exhaust gases. An excellent idea in theory and on paper BUT once the engine has been in service for a few years the EGR system and inlet manifold become caked in soot reducing air flow, increasing emissions and reducing power and mpg figures. Once the problems manifest themselves it is recommended that the EGR parts and inlet manifold are removed and cleaned (steam cleaning and physical scraping) to remove all the carbon and gunk. There are 'wonder aerosols' available that claim to clean out the EGR system. These aerosols have very limited effects and have the potential to cause damage (though our non caustic CARBON BLASTER has proved very impressive without
damage). The only way to do the job properly is to remove the parts and 'get involved'. Deactivating the EGR system is another option but not all vehicles will allow this to happen as the engine management light will illuminate.
Often overlooked but tyre pressures are a key player in economy figures.
Check and inflate tyres to correct pressures at least once a fortnight, pressure figures will be in vehicle handbook.
Very wide tyres will reduce economy, though look pretty cool.
SOME COMMON FAULTS
TRANSIT / LDV 2.0/2.4 - Fuel leak from injection pump quantity solenoid, fuel leaks onto starter motor (see Quick Fix's)
MAZDA 6 / MPV (Common Rail) - Engine cutting out at junctions, caused by failure of pressure control valve (See Quick Fix's)
MITSUBISHI 2.5 TD - Poor starting, leading to virtually impossible to start. Common fault is fuel pump worn out, requires rebuild.
MONDEO 2.0 TDCI - Intermittent non starting / cutting out. One cause (though there are many!) is cam shaft sensor failure.
RENAULT 1.9 DCI - Power loss, excessive smoke from exhaust. Turbo charger failure and / or intercooler split.
NISSAN X-TRAIL 2.2 DCI - Intermittent power loss, one possible cause is pressure control valve failure (See Quick Fix's)
BMW 320/330d - Lumpy / uneven idle, sometimes with grey smoke from exhaust, often caused by faulty injectors.
MERCEDES CDI - Lumpy idle, leading to grey smoke from exhaust that makes your eyes 'water', often caused by faulty injectors.
ISUZU 3 litre - a common fault is injector nozzles splitting, symptom: misfire and smoke.
NISSAN TERRANO 2.7 (MAVERICK) - springs inside injection pump are prone to collapse resulting in power loss, missing/shudder, smoke.
VAUXHALL ASTRA/VECTRA - engine cuts out, will not restart. Fuel pump fault, requires service or exchange unit.
FORD MONDEO/ESCORT - injection pump bearings collapse resulting in metal particles blocking advance solenoid. Symptom: blue/grey smoke at idle, lumpy/uneven idle speed.
VW TDI ENGINES - drastic power loss, causes: injection pump internal collapse or air flow meter fault.
LANDROVER GEMINI ENGINES - power loss, smoke, not stopping on key, cause: injection pump internal collapse.
FORD TDCI - Uneven running, poor starting, power loss, blue/grey smoke from exhaust, cause: Injectors faulty.
VAUXHALL 2.0/2.2 - Poor starting from cold or engine cuts out after a few seconds and requires lots of cranking to restart, cause: Injector leak off pipes perished/injector seals.
MITSUBISHI 2.8 - After starting from cold within 10 minutes the engine cuts out, once restarted runs fine, cause: Pump seal failure.
VW 'PD' ENGINES - Uneven running power loss, causes: Pump unit failure.
AUDI V6 TDI - Engine cuts out will not restart, cause: Injection pump failure.
FORD 2.0 TDDI/DURATORQ - Engine cuts out will not restart, cause: Injection pump failure.
VAUXHALL 1.7 (GM ENGINE) - Engine cuts out will not restart, cause: Injection pump failure.
COMMON RAIL ENGINES (ALL APPLICATIONS) - Engine fails to start or requires 'Easy Start' or a tow to start the engine or engine will not start at all, causes: Injector failure and/or high pressure pump failure.
TELL TALE SIGNS
There are a number of running problems that indicate something is 'not quite right'.
BLUE SMOKE from exhaust - Causes: Engine is burning engine oil, injection timing is incorrectly set.
BLACK SMOKE from exhaust - Causes: Too much fuel is being delivered to the engine or the fuel that is being delivered is not correctly atomised, Exhaust Gas Reciculation (EGR) system has failed or is incorrectly set of has become clogged with soot.
WHITE SMOKE from exhaust - Causes: If the ambient temperature is low, steam which is normal and usually clears, if the smoke never clears, water is entering the engine (cylinder head, head gasket, liner problem).
GREY SMOKE from exhaust - Causes: Injection timing is incorrectly set, fuel is not being atomised correctly, something other than diesel has been added to the the fuel tank.
METAL PARTICLES FOUND IN FUEL FILTER - Cause: Injection components have begun to disintegrate.
ENGINE MANAGEMENT LIGHT (MIL) ILLUMINATES - Cause: The engines ECU has picked up a fault, requires the vehicle to be plugged into a diagnostic code reader to identify/locate the fault.
VEHICLE GOES INTO 'LIMP MODE' - Cause: A serious fault has occured, requires the vehicle to be plugged into a diagnostic code reader to identify/locate the fault.
For Technical advice and help please click here