My van (602 disc engine) is running nicely - starts easily, revs freely, doesn't run-on when turned off, doesn't seem hot ...... but every now and then, when on the over-run (I mean, when you take your foot off the loud pedal) there's a very noisy bang in the exhaust. It's the usual LHD van, with the exhaust coming out on the driver's side not very far back, and at first I thought the noise was actually something heavy thrown up by the wheels hitting the inside of the rear wheel arch. But it wasn't.

There's also a bit of a smell when one slows right down - I'd have said brake pads, that kind of smell, but it isn't them, the calipers are nice and cool (I haven't checked the rear drums though). Is it most likely a hole in the exhaust somewhere? Might the smell be the firegum burning away?

I know this is normally easy to diagnose, but it's very wet and muddy at the moment here and grovelling about underneath isn't a very attractive option. How I wish I had that inspection pit I left behind in Kent.

Or should I be looking at tappets? It's got 123 ignition for what it's worth.

What is the condition of you rear engine mount (the one behind the gearbox). Mine is currently about to be replaced as it was a soggy oily mess. Once gone, they allow the engine to rotate, which may twist the exhaust up and hit the body.

Daffy Duck

Popping and banging from the exhaust on the over-run (lift off) is normally a leaky exhaust thats letting air in and the unburnt gasses in the exhaust mix with the air and make your noises.

This would probably also explain the smell your getting.

Hope that helps

Thanks Matt, a leak in the exhaust was just what it was.

And contrary to all the laws of nature, it was leaking at the joint that was easiest to get at - the one between the manifold and the heat exchanger, on the left hand side. So it was a fifteen minute job (of which ten minutes was finding where I had put the right size spanners).