Hissing sound and high engine temp

[jick.cejoco]

which came first, the chicken or the egg? which came first, the hissing sound or the overheating? the only time overheating makes a hissing sound is when pressure is leaking from the pressure cap or some weak point that can not hold pressure. in this case, the leak must be visible. but a hissing sound that was caused by a vacuum leak will definitely cause overheating and lose coolant through the radiatior cap or overspills at the recovery bottle. stop guessing.use a vacuum gauge to see that you have engine vacuum between 17- 21 inches of mercury assuming your camshafts are OEM and that the engine is neither supercharged nor turbocharged. use diagnostic instruments to digitize your results and stay away from amateurs.