General Engine Repair Checklist

Troubleshooting mechanical engine problems can be difficult and often time-consuming. This section lists possible engine problems that could be encountered with possible causes and corrections to investigate. The information given is of a general nature as it covers the basic engine and your particular application may be different. If you are in any doubt, contact your local distributor or contact us for help.

Before starting any dismantling procedure the following should be considered:

  • Do you know and understand the engine and all the related systems?
  • Do you have sufficient electrical and mechanical knowledge and skills to understand the symptoms?
  • Do you have suitable electrical diagnostic equipment available?
  • Do you have, or have access to, the necessary gaskets and spare parts before you commence dismantling your diesel?

Use our simple checklist below to help diagnose the issues with your engines.

  • Diagnose the problem by eliminating the easiest things first.
  • Before starting to remove or dismantle any components double check your observations.
  • During dismantling keep all cylinder related items together. This will ensure they are refitted in the original orientation.
  • When electrical troubleshooting always start at the battery first.

Difficulty Starting or Failure to Start

Incorrect starting procedure.

Ensure that you have followed all the correct procedures to help prime the engine and also ensure that the engine has been setup correctly to start. Refer to the manual for this process.

Unsuitable lubricating oil (too heavy).

Ensure that the engine has the correct viscosity of oil. Refer to the manual for the correct grade and the correct type of oil to use.

Check the correct fuel is being used

Please ensure any fuel supply to the engine is correct. Only by having the correct fuel will the engine start.

Is there fuel in the fuel tank?

Check to make sure that there is sufficient fuel present in the fuel tank. If not, top up the fuel to the recommended levels.

Choked Fuel Filter

If the filter is choked, replace the filter with a genuine spare part matching the required filter spec.

Air lock in the fuel system

Check to see if there is an airlock in the system. Check the fuel level and prime the fuel filter if needed.

Check for dirt or water in the fuel system

If there is dirt or water in the fuel system it will stop the fuel supply to  the engine. Drain, flush, refill and prime the fuel system.

Dirty of faulty injector

If you believe the injector is blocked or faulty, replace the filter or get the injector serviced and checked.

Discharged battery

Check the battery has sufficient charge to turn over the starter motor, if not, charge or replace the battery

Fuel pump solenoid not energised

Ensure all the electrical connections are connected properly and check power is being received to the solenoid.

Poor battery connections

Clean and replace the battery connections if necessary. Ensure a good clean connection at all times.

Faulty fuel pump

If you believe the fuel pump is faulty then it should be replaced with a brand new genuine spare.

Excess carbon deposits

Choked air filters

The air filter may be blocked. Dismantle and clean the cap and clean or replace the filter with a genuine spare.

Choked exhaust system

The exhaust system may be blocked or choked. Fully dismantle and clean thoroughly before re-assembling.

Unsuitable, or incorrect fuel

Ensure that the engine has been run on good quality, clean fuel. Check the manual for the correct specification of fuel.

Unsuitable lubricating oil

Ensure that the engine has the correct viscosity and specification of oil. If in doubt, drain the oil and replace with oil that matches the specification required

Continuous low, or no load running of the engine

Ensure that the engine is being run at sufficient speeds to clean itself. If the engine is being run on low, or no load, check the engine is the correct one for the application.

White exhaust smoke

Water in the fuel system

The fuel system has become contaminated. Drain, flush and replace the fuel system and filters with genuine spare parts.

Faulty fuel pump

Ensure that the engine is being run at sufficient speeds to clean itself. If the engine is being run on low, or no load, check the engine is the correct one for the application.

Light blue exhaust smoke

Check the running load of the engine

Ensure that the engine is being run at sufficient speeds to clean itself. If the engine is being run on low, or no load, check the engine is the correct one for the application.

Heavey blue exhaust smoke

Lubricating oil passing the piston rings

Check the crankcase vacuum on your engine. Take measurements and ensure the bores are not worn.

Stuck, worn or broken piston rings

Check for damage to the pistons and piston rings. Decarbonise and replace the rings or piston if damaged.

Worn cylinder bore

Replace the piston and piston rings.

Overfull oil sump

Check the level of oil in the engine. If it is too high, drain the oil to the correct level.

Black exhaust smoke

The engine is overloaded

Reduce the load that is running on the engine. Assess if the engine is sufficiently powerful for the application

Choked air filters

The air filter may be blocked. Dismantle and clean the cap and clean or replace the filter with a genuine spare.

Inlet air temperature too high

The air in the inlet is too hot. Check fresh air supply to the engine and adjust.

Water in the fuel system

Water has penetrated the fuel system. Drain, flush, refill and prime the filters before starting the engine.

Unsuitable fuel

Ensure that the correct fuel type and specification is being used. Replace if necessary.

Engine stops running

Lack of fuel

Ensure there is sufficient fuel in the fuel tank. Refill if required.

Air in the fuel system

Ensure the fuel system is bled and prime the fuel filter to ensure no air is present.

Water in the fuel system

Water has penetrated the fuel system. Drain, flush, refill and prime the filters before starting the engine.

Choked Fuel Filter

If the filter is choked, replace the filter with a genuine spare part matching the required filter spec.

Choked air filters

The air filter may be blocked. Dismantle and clean the cap and clean or replace the filter with a genuine spare.

The engine is overloaded

Reduce the load that is running on the engine. Assess if the engine is sufficiently powerful for the application

The engine is over heating

Check the section below for details on why the engine may be overheating

Loss of compression

Check to ensure there is no damage or wear to the piston rings. Also check the valves to ensure a good seal is present.

Loss of electrical supply to the solenoid

Ensure all electrical connections and cables are connected properly. Replace any damaged cables and tighten any connections if needed.

Automatic shutdown protection

If there are any automatic shutdown devices attached to the engine, these should be checked and cleared.

High fuel consumption

Incorrect fuel

Ensure that the correct fuel is used. Drain and replace if required.

The engine is overloaded

Reduce the load that is running on the engine. Assess if the engine is sufficiently powerful for the application

Dirty of faulty injector

If you believe the injector is blocked or faulty, replace the filter or get the injector serviced and checked.

Choked air filters

The air filter may be blocked. Dismantle and clean the cap and clean or replace the filter with a genuine spare.

Lack, or loss of power

Loss of compression

Check to ensure there is no damage or wear to the piston rings. Also check the valves to ensure a good seal is present.

Choked air filters

The air filter may be blocked. Dismantle and clean the cap and clean or replace the filter with a genuine spare.

Choked exhaust system

The exhaust system has need to be dismantled and cleaned. Reassemble once fully cleaned.

The engine is overloaded

Reduce the load that is running on the engine. Assess if the engine is sufficiently powerful for the application

Choked Fuel Filter

If the filter is choked, replace the filter with a genuine spare part matching the required filter spec.

Worn engine

Your engine may be worn. Schedule a complete overhaul of the engine and ensure only genuine parts are used.

Engine is overheating

The engine is overloaded

Reduce the load that is running on the engine. Assess if the engine is sufficiently powerful for the application

Lubricating oil level too low

Top up the oil to the correct levels. Ensure the correct specification of oil is used. Check the engine manual to determine the correct type and viscosity of oil.

Incorrect fuel

Ensure that the correct fuel is used. Drain and replace if required.

Recirculation of exhaust gases or cooling air

Investigate airflow of the engine and correct where necessary

Air cooling system obstructed.

Check for restrictions and clean the cylinder head and cylinder barrel cooling fins. Ensure all areas are not obstructed.

High fuel consumption

Incorrect fuel

Ensure that the correct fuel is used. Drain and replace if required.

The engine is overloaded

Reduce the load that is running on the engine. Assess if the engine is sufficiently powerful for the application

Dirty of faulty injector

If you believe the injector is blocked or faulty, replace the filter or get the injector serviced and checked.

Choked air filters

The air filter may be blocked. Dismantle and clean the cap and clean or replace the filter with a genuine spare.

Undercharging

Excessive electrical load from added accessories

Check what is connected to the engine and remove any accessories needed to bring the charge to the correct levels.

Poor electrical connections to alternator or battery

Ensure all of the connections and cables are in good condition and clean. Replace where necessary.

Faulty battery

Test the battery and replace or recharge where necessary.

Faulty alternator or charge windings

Test and replace any faulty parts where necessary. Test before using the engine again.

Overcharging

Faulty alternator or charge windings

Test and replace any faulty parts where necessary. Test before using the engine again.

Battery will not charge

Loose or corroded connections

Check and clean the connections on the battery. Replace where needed with genuine spare parts.

Worn out battery

Test the battery and replace where needed.

Loose alternator drive belt

Check the tension of the drive belt. Replace with a genuine drive belt.

Starter Motor does not Operate

Loose or corroded connections

Check and clean the connections on the battery. Replace where needed with genuine spare parts.

Worn out battery

Test the battery and replace where needed.

Faulty starter panel or connections

Check the connections or replace the panel.