Strange popping / dripping sound when idling

[webbiegareth]

Hi all,

Our Ford AU has a very strange "popping" sound when idle, it's NOT in time with the engine - it seems totally random, kind of like water dripping onto a metal surface. It sounds stronger from the driver's side of the engine, and you can hear it louder sticking your head under the car.

I suspected an exhaust manifold leak as I knew the muffler had a few holes and the mechanic thought there was a hole in the engine pipe as well (between cat and manifold).

Here was the original video:

http://youtu.be/thrqtC3I5wY

You can hear it loudest when I walk in front of the car and lean on it a bit, right before I start revving the engine - you can't hear the sound anymore of the sound of it revving, only when it's idling.

Oh and I realise how bad it sounds when it's revving... it's an old engine, I just want it to last as long as possible then we'll put in a newer engine. So all the repairs we're doing to the car is everything apart from the engine

We've now had pacemakers, new metal cat and a redback 2.5" catback exhaust fitted. The damn sound is still there!

http://youtu.be/9742LdDf7v0

(totally out of focus, but that's with the new exhaust system fitted).

Does anyone know what the hell this sound is?