Chuffing Noise Under Acceleration

[FunkyFez]

The title says it all. The car sounds like a small steam train wher you ure under any sort of acceleration. The exhaust has been checked from end to end and there is no sign of any air leaks, but when you start driving it makes a chuffing type of noise all through the rev range. I suspect that something is worn, but don't know where to begin looking. I also suspect a blown exhaust manifold gasket, but who knows.
It sounds fine on idle so i'm stumped. HELP!

 

[panason1c]

To check the exhaust, including the manifold, for leaks have someone block the tail pipe with a rag and any leak will be more pronounced at tickover.

 

[EDZ649]

Have you checked all the air intake system? I had a split in on of the rubber hoses that only opened up when the accelerator pedal was pressed, didn't show at idle.

 

[FunkyFez]

Just had another look at the cats. The small NSF unit is rattling when you give it a tap with a screwdriver. It doesn't appear to rattle when driving. Could this be generating the sort of noise i'm hearing?

 

[panason1c]

err, no, it would give off a rattling sound.



one of the exhaust manifold gaskets blown is the more likely. (or a cracked manifold)

 

[FunkyFez]

Exhaust manifold seems plausable. The noise has been there for months but has been much louder this morning. Not any noticable performance loss.
Looks like another trip to the indy is on the cards.

 

[lynall]

Looking at friends vw weekend she said exhaust blowing, no leaks found but cat rattles when tapped and if you listen carefully its not leaking but sounds like a straight through pipe



Lynall