I just noticed a low whistle sound that comes and goes. Is coming from the engine. It doesnt matter with the speed. Is a 1990.
Check the air intake filter. If it is a whistling sound, it may be air coming into the motor causing it. Remove the air cover and make sure it is clean. Remove the filter then and start the car and see if that eliminates the sound. Oil leaks and coolant leaks will not produce a whistle sound, same as a water hose does not. Does the engine still run smooth or is it running rough? Is the gas mileage the same or worse now the whistle has started? It my be in the fuel delivery system with a slight leak from the gaskets. Check the air intake first though.
I'll point to the fan clutch as being the culprit. Lift the hood and start the vehicle...have someone watch the coolant fan(the big fan in front of the motor) and shut off the vehicle. If the fan keeps spinning, then it has a bad clutch...culprit found,
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