thumping noise - w220 s430

[jonnyboy]

Hi all

Weird one this. Fault only noticed whilst sitting idling as no chance of noticing it whilst driving:

Sitting in car with it warm, idling, i noticed a rhythmic thumping/thudding coming from the front end, possibly the bulkhead. Sounds like a motor/solenoid/valve opening and closing but happening at 10 second intervals or less. Its subtle, but there. I can't imagine MB would produce a car where this was noticeable so I suspect it to be a fault. It was just noticeable through the footrest as well as audible.

Any pointers? car is a 2000my s430 lwb with every option known to man, 46k miles, airmatic susp.

Thanks

 

[portzy]

Have a look/listen to the heating duovalves in the engine bay, they are normally quite near the bulkhead on the off side. These can give this type of effect although I'm lead to believe its not a problem so long as the heating/cooling systems are working as they should.

Portzy.