M48 Family

Porsche M48.50
Porsche M48.50 – photo by The Car Spy

Porsche M48 Family

All Engines

  • Ignition coils

M48.00

  • The plastic coolant pipes under the intake manifold very commonly burst – Porsche released an upgraded aluminum part which is much stronger
  • There have been reports of bore scoring. It is unclear if this only effects MY03-04 vehicles, or all vehicles with this engine. A borescope inspection should be mandatory as part of a PPI. There are several theories about why this happens, but none of have been confirmed:
    • Overheating due to failure of the plastic coolant pipes (described above)
    • Taking many short drives without allowing the engine to run at normal operating temperature for long. This means the condensation that forms while an engine is warming up does not burn off, and eventually mixes with fuel and oil that leak past the piston rings when the engine is cool. The ensuing mixture is acidic and causes damage to the cylinder walls.
    • There are two other theories that conflict with each other, as it is unclear whether the engine does or does not have cylinder liners:
      • The Nikasil cylinder liner that Porsche used for this engine is too weak, but the M48.50 engine does not have bore scoring issues because it had a stronger cylinder liner
      • The engine has no cylinder liners, and Porsche incorrectly believed that the engine block – which was made out of Nikasil – was strong enough that it didn’t require them. The M48.50 engine didn’t suffer from bore scoring because it had more oil spray, and therefore the pistons ran cooler than in the M48.00 engine – which meant they didn’t expand as much within the cylinder walls and rub against them.

M48.01

  • Upper front coolant pipe can slip out of housing due to a glue failure
  • Engine rear coolant crossmember to both cylinder banks can slip out due to glue failure. Symptoms are a coolant leak coming from the rear of the engine. Fixing it usually requires removing the engine. An updated part was released which is threaded.
  • High pressure fuel pump
  • Vacuum pump can fail, causing oil to get into the vacuum lines and damage servos under intake – symptoms include a CEL and evap system failure

M48.50

Unlike the M48.00, the M48.50 is not susceptible to bore scoring.

  • The plastic coolant pipes under the intake manifold very commonly burst – Porsche released an upgraded aluminum part which is much stronger
  • Oil may leak from the pressure hose

M48.51

This engine suffers from the same issues as the M48.01.