Hissing sound from engine just after engine stopped.

[steve116]

I have a series 2 E Type 4.2 coupe manual. Just recently I have noticed a strange sound when I turn the engine off. It sound like hissing, or liquid flowing under pressure, and is coming from the engine. It is hard to say exactly whereabouts, but I think it is from the top of the engine rather than lower down. The sound is noticeable as soon as I switch the engine off, and lasts for about ten seconds. The sound is also noticeable from inside the car. It makes no difference if the engine has been running for a while or if I start it up and immediately switch off again, it still makes the same sound for about ten seconds. Other than that the engine runs normally and all the gauges are normal. The car drives normally and there is no loss of performance. Any suggestions as to what this might be would be gratefully received. Many thanks. Steve Williams.

[mike020150]

Could it be a less than perfect coolant cap seal? Pressure in the coolant system could be forcing either air or coolant past a defective seal, dependent upon coolant temperature and how full the system has been filled. Mike.