1991 Bentley Turbo 6.8L Petrol · J404 TKG

The Turbo R utilises a Citroën-licensed high-pressure dual-circuit hydraulic braking and self-levelling suspension system powered by two engine-driven mechanical pumps. Over time, the nitrogen-filled spherical brake accumulators lose their charge, internal seals in the brake distribution valves degrade, and corrosive mineral fluid (or incorrect DOT fluid mistakenly added) ruins the internal rubber seals. This causes rapid pedal stiffening, delayed braking assistance, and pump cavitation.

The cast iron exhaust manifolds and heat-cycling gaskets on the turbocharged 6.75-litre V8 undergo intense thermal expansion and contraction cycles. The massive heat retained in the SZ engine bay causes the cast iron manifolds to warp or develop hairline fissures, while the copper-clad composite manifold gaskets burn through, creating sharp ticking exhaust leaks on cold startup that can damage cylinder head studs.

Post-1990 Turbo R models feature an electronically modulated Active Ride damping system with hydraulic gas spring accumulator spheres. Over 8–10 years, the nitrogen gas permeating the internal rubber diaphragms leaks into the hydraulic fluid, eliminating pneumatic damping cushion. This forces the hydraulic fluid directly against solid strut stops, causing severe ride harshness, damper seal blowouts, and fractured rear subframe mountings.