On a 2001 Freelander TD4 diesel, I'm hearing very loud banging noises when the engine is idling a few seconds after ignition. It sounds like the normal engine "cluk" sound but five times as loud.
I've heard similar noises before when doing a tight corner, but only yesterday when we switched on the air conditioning, this problem has become much worse and wouldn't go away.
At higher revs, the sound seems to fade away but immediately returns when you idle again. There's no smoke and no apparent loss of power. Everything's okay except the noise, except I'm afraid it's doing damage somewhere.
We've already replaced the engine oil filter and oil just in case it wasn't circulating properly, but it hasn't had any effects.
Anyone have any ideas? We have a bit of experience with the mechanics of petrol cars, but not diesel engines.