Overheating in the Compact Engine Bay
Symptoms
Temperature gauge climbs in traffic or under sustained load. May push coolant out the overflow. Engine pings (detonation) under acceleration.
Cause
The 253 and 308 V8 engines generate significantly more heat than the six-cylinder they replaced in the Torana's engine bay. The engine bay was originally designed for the six, and while the LH/LX were adapted for the V8, the cooling system clearances are tighter than in the larger HQ/HJ/HX sedans. The factory radiator is often marginal, particularly in the 308. Hot exhaust manifolds radiate heat into the confined space, and the thermostat housing is close to the carburettor, causing fuel vaporisation (vapour lock) in extreme conditions.
Fix
Upgrade the radiator to a 3-core brass or aluminium unit ($400-800).
Fit an electric thermo fan behind the radiator ($150-250) to improve low-speed cooling.
Wrap or ceramic-coat the exhaust manifolds to reduce underbonnet heat.
Ensure the thermostat is the correct 82°C rating.
Check the water pump for leaks and impeller erosion.
Consider an insulating gasket between the carburettor and intake manifold to reduce vapour lock.
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