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Bonus - Jackaroo Manual
Maintenance manual

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Smoke emmisions

Smoke emissions can be a useful diagnostic tool:


A common smoke emitted from diesel engines, indicating poor and incomplete burning of the diesel fuel.

Causes include:

  • Incorrect timing
  • Dirty or worn injectors
  • Injectors staying open too long (Common Rail Diesel type)
  • Over-fueling
  • Faulty turbocharger (ie not enough air to match the fuel)
  • Incorrect valve clearance
  • Incorrect air/fuel ratio
  • Low cylinder compression (eg sticking piston rings or worn components)
  • Dirty air cleaner
  • Restricted induction system (eg system too small or kinked inlet piping)
  • Carboned up intake manifolds (esp Common Rail Diesels)
  • Other engine tune factors
  • Poor quality fuel
  • Excessive carbon build up in combustion and exhaust spaces
  • Cool operating temperatures


An indication of oil being burnt. Oil can enter the combustion chamber for several reasons:

  •  Worn valve guides or seals
  •  Wear in power assemblies (ie cylinders, piston rings, ring grooves)
  •  Cylinder glaze
  •   Piston ring sticking
  •   Faulty turbocharger seals
  •   Incorrect grade of oil (eg oil too thin, and migrating past the rings)
  •   Fuel dilution in the oil (oil thinned out with diesel)


Emission of crankcase pressure (and fumes/smoke) out of the crankcase ventilation system, and generally regarded as a clear indication for an engine rebuild.

It is evident as pressure coming out the crankcase ventilation tube, valve cover breather or dipstick tube.

Some causes include:

  • Sticking piston rings
  • Worn cylinders
  • Worn or broken piston rings
  • Cracked pistons


Common in the 4JX1, with failure of the injector tube o-rings. This is the coolant burning off as steam showing in the exhaust pipe. At this point, need to replace the injector o-rings as quickly as possible before more damage is done.

Could be:

  • Coolant in the diesel;
  • Cracked head [uncommon];
  • Failure of the water pump, overheating and pressuring of head.