This is the best way I can describe it. Lately i've been noticing this noise, loud only under throttle. It sounds like the old VW Beetle cars or kinda like baseball cards in the spokes of a bike wheel. I don't know when it began but it's gotten worse because it didn't bother me befor but it really bugs me now. You can't really hear it when on the highway but you can hear it when driving slow with the windows down.

I was thinking it was an exhaust leak. But I've taken it to an exhaust shop twice and this guy couldn't find anything. (maybe need to try another mechanic) I just would like to know if anyone else has or is experiencing this noise, and if so, what you're doing about it.

BTW: I have a 2.8, 98.5qm

Sounds loud when in-gear under throttle. Not really noticeable when not in gear. I'm thinking it's some kind of manifold leak. Wish I know how to find it.

Def look for a manifold leak if you think it is coming from under the hood. Try to find out where it's coming from and it would be much easier to nail down what it is.

think is correct

Any luck with solving this yet?

Do you have a sound clip?

when driving. This weekend though, I'm going to try putting some powder on the down pipe in and look for places where pressure is plowing the powder up. If I can at least find the leak, I can at least tell an exhaust shop where it is to fix it. Or I may try to tackle it myself with some kind of sealant.

Man i wish I could hear your car...I dont know what a deisel engine sounds like but the baseball card in the spokes is one way I was thinking of describing my problem. Does it sound like fan blades whapping on something slightly metallic as your RPM's increase under load.
Mine only happens under WOT, is it the same for you?

and I saw where the cat downpipe attaches to the manifold. The connection, where I had an exhause mechanic put in a gasket for me, didn't look as evenly attached as the other side. Everything looked sightly off. I think he leak is comming from that section. It seems to get slightly louder with time. I'll take it to a mechanic next time.