On the revised long-hood cars the engine saw significant development (2.0 to 2.2 to 2.4 litres). One important change was the introduction of magnesium crankcases from the end of 1968. These are lighter, but more prone to corrosion and distortion (pulled head studs).
- Oil leaks: crankshaft seals, pushrod tube seals, cam covers (cost: €500-€3,000)
- Chain tensioner: the mechanical tensioners tend to fail (conversion: €500-€1,500)
- Valve guides: wear leads to oil burning (overhaul: €2,000-€5,000)
Mechanical fuel injection (MFI): a technical highlight on the E and S cars. It gives an immediate throttle response, but it is complex. Problems: worn throttle shafts, an injection pump out of adjustment (the three-dimensional space cam), the warm-up regulator (MFI repair: €500-€4,000).
Carburettors (911 T): easier to service, but also prone to poor setting up or air leaks (cost: €500-€2,000).
A warning on costs: a complete engine rebuild (including machining the case) can quickly reach €15,000 to more than €30,000.