Jaguar XJS 3.6 from VIN...179736, XJS 4.0 to engine no. 196089, XJ40 2.9, 3.2, 3.6 and 4.0 from VIN...500001 to 708757
These so-called stretch bolts are specifically designed to give a set length under the right torque. As such they should never be used a second time. The desired bias requires careful installation. The cylinder head bolts are assembled in several stages with a specific tightening torque. When this torque is reached, the bolts are turned further through a defined angle which pre-loads them into a plastic region. We recommend that new cylinder head stretch bolts be used and any work carried out to your engine is done in accordance with a factory workshop manual. Whilst you are doing this job we consider it advisable to replace the water pump and expansion cap to minimise any future problems.