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Land Rover Tdi Overheated or Blown Engine

Land Rover Tdi Engines used in Defender and Discovery like many other turbo diesel engines can suddenly overheat due to loss of coolant or cooling.

Tdi engine is a somewhat stressed engine that uses an alloy head on a steel block. The engine relies heavily on good oil pressure and good cooling.

If the oil pressure or cooling is interrupted or removed for even a short period, the engine will very quickly burn out.

Common reasons for this happening are:

  • Radiator hoses fail or come off due to improper fitting or hose damage
  • Plastic thermostat and radiator plugs disintegrate without warning
  • Serpentine belt breaks, leaving the water pump stationary
  • Broken or seized Power steering, idler or air-con pulley leading to main belt failure and stationary water pump.
  • Accumulated sediment in the radiator.
  • Low cooling fluid level due to negligence or leakage
  • Incorrectly torqued head or Air cleaner mounting bolts
  • Incorrect Diesel mixture or timing leading to high Exhaust Gas Temperatures (EGT)

As preventative measures, always ensure the above items are taken care of - never assume anything or try "just make it home", you will be sorry. The plastic radiator plugs can be replaced with solid brass plugs as originally fitted to Range Rover engines.

It is becoming increasingly common that people assume the Tdi to be an extremely expensive engine to repair after a burnout.
The main reason for this is that it is believed that the cylinder head cannot be skimmed and if not within spec, must be replaced - this is an expensive chunk of aluminium - in the region of R 8000 !

When a Tdi engine overheats badly for what ever reason, the following things happen: 

1) Cylinder head warps - by as much as 2mm over the length

2) Two middle pistons start to heat seize to the bores - the alloy of the pistons sticks to the steel sleeve.

3) Outer two pistons also heat seize and the cylinder head may actually crack.

There are 3 different thicknesses of cylinder head gasket available for the Tdi - This is to accommodate differing head thickness after skimming.

If the head has been skimmed before or the warp age of the head is so severe that the head is too thin the head is believed to be useless as the thickness does not determine compression but determines the valve  to piston clearance measurement. If this clearance is too little, the valve will hit the piston crown causing severe damage to the valve train and piston.

It is possible to have the cylinder head metal sprayed,  such that it is back to the original new specification.
The procedure entails heating the head up and spraying molten aluminium onto the head surface, the surface is then re-machined back to new - original spec, the valves are re-seated and the head is as good as new. This procedure costs less than 1/8 of the price of a new head and is as good as a new head.

It may also be possible to have head cracks repaired in this way as it involves heating of the entire cylinder head and effectively resurfacing the head, this however has not been tried yet.

Generally speaking, if the engine overheated due to water or cooling trouble, the bearings and general sub assembly is still fine and need not be rebuilt.

Disco Tdi Overheating
Overheating of mainly Discovery Tdi vehicles due to the failure of a variety of components. To complicate matters more it appears that the temperature gauge did not alert owners of the problem, resulting in severe engine damage. 

There are really 3 components in question:
The first is a the standard flexible gasket (ERR3284), that has subsequently been replaced with an improved aluminium version (PET100790). The second has to do with the radiator hose coming loose or even failing. Then lastly the over tightening resulting in damage or stripping of a plastic radiator filling plug.

Installing an engine monitoring system like the Madman EMS (available from LandyOnline Retail) will provide peace of mind on engine monitoring and performance and alert you before it is too late.

 

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LandyOnline - Land Rovers in Africa  2000 - 2012                   Last updated 08/09/2012