air popping sound

[mark.t]

the car has a air popping sound a bit like potatoes bubbling in a pan for about 5 mins after the car is switched off its on the manifold side anyone any ideas below is the picture its item number 53 there are 3 lines off it one with a filter that's where the air is going into or coming out of if i squeeze tube 74 the popping stops

 

[BlackC55]

53 is a vacuum transducer.
Can you record the sound?

 

[mark.t]

like a pan of simmering water when the lids gentley lifting got a feeling its the same as this but could be wrong http://www.mbclub.co.uk/forums/showthread.php?t=37708&highlight=vacuum

 

[BlackC55]

Ask dieselman. He will probably know. I have no recolection of this sound.

 

[Dieselman]

It's the EGR vacuum transducer.
Don't worry about it, they all do it to a greater or lesser degree.

 

[mark.t]

thanks dieselman what does it do ....

 

[Dieselman]

Applies vacuum tot eh EGR valve as necessary. The popping sound is just vacuum leaking back through when the engine is switched off.