1995 Lamborghini Diablo 5.7L Petrol · B4 BUL

The Diablo's 5.7-litre and 6.0-litre V12 engines transfer up to 457 lb-ft of torque through a single dry-plate clutch. Due to high vehicle mass and heavy low-speed gearing, the clutch disc experiences rapid friction material wear during stop-start UK driving, rarely lasting beyond 20,000 to 25,000 miles. Furthermore, pre-1998 cars employ a pull-type hydraulic slave cylinder mechanism where the internal operating rod is prone to fatigue fractures or hydraulic seal blow-out, suddenly leaving the driver unable to disengage the clutch. Replacing the clutch assembly requires dropping the rear suspension, differential, and V12 powertrain, resulting in substantial specialist labour bills.

Early 1990–1994 Lamborghini Diablo 5.7-litre V12 engines used oil-pressure-fed hydraulic timing chain tensioners that suffered from a dangerous design flaw: engine oil pressure pulsations progressively ratcheted the tensioners tighter against the guide rails until excessive tension caused one or both timing chains to snap. This catastrophic failure resulted in complete valve-to-piston collision, destroying cylinder heads, pistons, and liners. From 1994, Lamborghini superseded these with mechanical ratchet tensioners and issued service bulletins to retrofit earlier engines. In addition, high-mileage Diablos can experience timing chain stretch, producing an audible rattle on the overrun.

The Diablo construction combines hand-beaten aluminium body panels mounted over a rectangular-tube steel spaceframe, with composite carbon-fibre used for the bumpers, sills, front bonnet, and engine cover. Inadequate galvanic barrier protection at the factory allows electrolytic corrosion to occur where the aluminium skin makes direct contact with the steel subframes. When exposed to damp British roads and winter salt spray, moisture is trapped within unsealed seams, causing galvanic blistering of the aluminium paintwork and structural rusting of the tubular steel chassis. Areas worst affected include the lower door bottoms, outer sill mounting points, front boot floor, and fuel filler pocket.