How to Troubleshoot an Overheating 1991 Nissan 300Zx Twin Turbo

Still one of the most recognizable road cars today, the 1991 Nissan 300ZX twin-turbo features a sleek shape with distinct, futuristic looks, and performance to match. Available in either hardtop or T-roof configurations, it offered stunning performance and a surprisingly spacious interior with its unique, extended 2+2 configuration. The potent 3.0L twin- turbo, six-cylinder motor was able to crank out 300 horsepower in stock trim, although many owners quickly recognized the VG30DETT engine responded well to modifications; they added bolt-on components to liberate even more power. Although it garnered many awards and accolades from the motoring press and public, it was not immune to the occasional failures or mechanical issues which every owner may face.

Instructions

1

Flush the vehicle cooling system. Over-heating can be caused by dirty or brown coolant; contamination reduces or ruins the cooling properties. Typically, manufacturers call for a 50/50 mix of water and coolant, although using pure coolant in cold climates may be necessary to prevent freezing.

2

Replace the thermostat. A stuck or improperly operating thermostat prevents the flow of cool water from the radiator, and causes heat to build up around the engine.

3

Check the radiator and fans, and replace them, if necessary. Radiators with damaged fins or inoperable fans are not able to sufficiently lower the temperature of hot coolant as it exits engine passages.

4

Remove the water pump and check it for sign of wear, such as failed bearings. The water pump has a limited life expectancy, and needs to be replaced at regular intervals.

5

Remove and examine spark plugs for signs of coolant build-up, which indicates a weak or blown head gasket. This will quickly send engine temperatures into the red zone.

6

Read any CEL (check-engine light) codes through the diagnostic port. This will help you to identify any other failed components quickly and accurately.