Overheating and Sweet Smell Around Engine on Toyota Supra

Submitted by casey40510 · May 29, 2025
Published by RepairPal

Problem overview

The Toyota Supra and Supra Turbo from 1986-1992 (MKIII) is known to leak engine coolant and overheat due to a leaky heater control valve. Drivers will notice a decrease in heater performance, and increase in engine temperature.

The purpose of this valve is to control the amount of heat that enters the cabin of the vehicle. If this valve has failed, it is recommended to use the OEM part for replacement.

Please note, the engine in both versions of the 1986-1992 Supra is prone to head gasket failure, so it is imperative that any coolant issues are addressed immediately to avoid costly repairs.

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