Toyota 5M / 6M / 7M

Toyota's straight-six before the JZ — the 2.8 5M and 3.0 7M — in the Supra, Cressida and Crown.

⚑ The 7M-GTE's head gasket is the most famous failure in this family and the cause is documented. Toyota under-torqued the head bolts from the factory; the gasket lets go between the cylinders and the coolant passage, and the standard remedy is a re-torque to a higher figure with a metal gasket rather than a like-for-like replacement. A repair that reuses the factory specification fails again.

It is belt-driven and it is an interference design, on cars now thirty to forty years old with unknown history.

Its other recurring items are the era's: a distributor that fails with heat, an air-flow meter that ages and skews fuelling, and oil leaks from seals long past their design life. The 1JZ and 2JZ that replaced it have their own page here, and the swap is common enough that a Supra's badge is not evidence of what is fitted.