Skip to content
MOTRS

Supra (A70)

1986-1993 / Coupe / Japan

All Supra (A70) problems All workshop issues
Common Engine, 7M-GTE (Turbo)

Head Gasket Failure

Symptoms

The head gasket blows, allowing coolant into the combustion chambers and/or oil passages. White smoke from the exhaust, coolant loss without visible external leak, overheating under boost, milky oil on the filler cap, and bubbles in the coolant overflow tank. In severe cases, hydrolock (coolant filling a cylinder and bending a connecting rod on startup).

Cause

Toyota designed the 7M head with only 10 head bolts, insufficient clamping force for the cylinder pressures generated under boost. The factory composite head gasket degrades over time and eventually fails. Thermal cycling accelerates the process. Every 7M-GTE will eventually blow a head gasket on the factory bolts, it's a matter of when, not if.

Fix

Strip the head, machine it flat (check for warpage, common after overheating), install a Cometic multi-layer steel (MLS) head gasket, and secure it with ARP head studs (part number 203-4205).

The ARP studs provide dramatically more clamping force than the factory bolts.

While the head is off, replace the valve stem seals.

Retorque the studs to ARP's specification (typically 85 ft-lb with ARP moly lube).

Total cost: $1,500-2,500 including machining, gaskets, studs, and labour.

Cost mentioned in fix
cost: $1,500-2,500 including machining

Know something we don't?

Owned a Toyota Supra (A70)? Share your experience with this issue. What worked, what didn't, costs, tips. Help the community.

Submit an update
// More Supra (A70) problems

Other known issues

Critical Engine, 7M-GTE (Turbo)

Low Oil Pressure at Idle

Oil pressure drops below 10 psi at hot idle. The factory oil pressure warning light may flicker or illuminate at idle, particularly in traffic on hot days. The engine may develop bearing noise (deep knocking from the bottom end).
Common Engine, 7M-GTE (Turbo)

CT-26 Turbo Failure

Loss of boost pressure, excessive oil smoke (blue/grey) on startup or deceleration, whistling or grinding noises from the turbo, and oil in the intercooler piping.
Critical Engine, 7M-GTE (Turbo)

Cooling System Inadequacy Under Boost

Coolant temperature climbs rapidly under sustained boost, particularly in traffic or on hot days. The temperature gauge sits higher than normal and doesn't recover quickly.
Common Engine, 7M-GTE (Turbo)

Fan Clutch Wear

The engine runs hotter than normal, particularly at low speeds and idle. The cooling fan doesn't seem to pull much air through the radiator.
Critical Engine, 7M-GE (Naturally Aspirated)

Head Gasket Failure (Less Common)
Common Transmission

W58 Synchro Wear

Crunching or grinding when shifting into 2nd or 3rd gear, particularly when cold or during quick shifts. The synchros may improve slightly once the gearbox oil is warm.
View all 17 Supra (A70) problems