These are some of the common things your mechanic should check
Starting a diesel engine during cold weather can be frustrating if the engine is not properly maintained for lower temperatures. Batteries that are weak may not crank the starter motor fast enough or long enough to start a cold engine. As the temperature goes down, so does battery capacity. The engine will be 2.5 times harder to start at 0 degrees due to thicker oil and resistance to movement of internal moving parts. Starting a diesel engine depends upon three things the flow of diesel fuel, heat at the point of combustion, and a battery with enough cranking power to turn over the engine. All these three elements are tested by cold weather.
However there are other problems associated with diesel engines
Faulty cylinders, the chambers where the pistons that ignite the engine move, can cause low cylinder compression. This will result in insufficient heat being generated to ignite the fuel and cause hard starting.
Low fuel pressure
Low fuel supply to the injectors or worn injectors that cannot hold the fuel pressure.
Low cranking speed or faulty battery
If the engine turns over too slowly, the injection pump cannot generate enough fuel pressure, and the piston speed will be too low to generate a high enough air temperature to initiate combustion, causing hard starting problems.
Thermo start or glow plugs faulty
Problems in this area will cause starting problems, uneven running and white smoke when the engine is cold.
Poor or low fuel supply
If there isn’t enough fuel in the tank or there’s a problem with the fuel pipes being split or kinked the fuel supply can be restricted. The fuel tank cap breather can sometimes be blocked causing a vacuum in the tank.
Poor quality fuel and water in the fuel can cause injection pump and injector failure. Filters and sediment bowls must be changed and drained regularly. Diesel contaminated with other fuels is a fairly common problem. Most pump and injectors failures are due to fuel related issues.
Air in fuel
Loose or faulty fuel pipe connections can allow air to be drawn into the system. Dirty fuel filters or a faulty filter head assembly may also cause fuel supply issues and hard starting.
Fuel filter or fuel pipes blocked
Dirty fuel containerstanksfuel can cause filters in the tank, lift pump, and main filter to become blocked. They must be cleaned or changed on a regular basis.
The greatest cause of injector failure is due to the injectors having worn needles and nozzles or a build up of carbon. This can cause a poor spray pattern or fuel ‘Dribble’. This results in hard or poor starting.
Injection pump faulty
If the pump is faulty there will be a ‘Low fuel pressure’ problem.
Fuel lift pump faulty
Known faults in the lift pump are: – Split diaphragms and leaking, loose or displaced non-return valves. If the lift pump is faulty there will be a ‘Low fuel pressure’ problem, a split diaphragm will dilute the engine oil with diesel.
Blocked or Dirty air cleaner
A blocked or dirty air cleaner element can severely restrict air flow to the engine. Whether it is an oil bath or dry element air cleaner it must be serviced at regular intervals.
The most common turbocharger fault is due to incorrect operator actions (Not allowing the engine to idle when started and before stopping), poor maintenance and not using the correct type of oil.
Injector washers leaking
Leaking injector washers can cause hard or difficult starting, erratic or uneven idle speed, lumpy running, smoke on idle, a black deposit around the injectors and a characteristic chuffing sound from the engine when running.
Internal engine faults
This is usually a mechanical failure such as cracked pistons, worn or broken piston rings, low oil pressure, overheating, blowing valves, cracked liners, leaking liner seals, blowing head gasket, worn bearings, leaking valve seals and much more. The list is endless, so it is best to get an engine specialist to diagnose the fault.
Source : The Independent