Transmission tunnel rattle and whats this (pic)

[Ken Figenus]

Had the car on a ramp today as there is a strong rattle at certain rpm from the transmission tunnel gearbox area (if it were a std layout car of course). Bit of a metal on metal rattle noise at 30mph in 3d and 40mph in 4th but exhaust hasnt moved, manifolds good - couldnt see anything visible that was loose or touching. Anyone had this?

I then treated myself to a root around the engine bay with a feather duster and spotted this as it looked a bit loose:



Its like a bung in the intake manifold/plenum. Black bit can be pulled out like a choke knob! There is the same hole on the other bank which has a sensor and thick cable (prob intake manifold pressure sensor?) but all seems one sided and an odd 'bung' for a highly pressure sensitive component. Any ideas?

[FrankieV12VSBee]

Ken,

No idea what the bung is but I had similar rattle, usually under deceleration. It turned out to be the exhaust heat shield being slightly loose and catching on the exhaust.

[Murph7355]

It might help if you put a pic panned out

[GingerMunky]

Ken Figenus said:

I then treated myself to a root around the engine bay with a feather duster and spotted this as it looked a bit loose:

I knew you were into feather dusters glad it is being used well

[StephenP]

FrankieV12VSBee said:

It turned out to be the exhaust heat shield being slightly loose and catching on the exhaust.

That would have been my first guess and worth a check before anything else.

Alternatively degraded/damaged rubber mounts somewhere allowing two metal parts of the mount to contact each other briefly. Not sure if it applies to this particular model, but gearbox mounts or exhaust hangers spring to mind. Most likely under load or overrun.

Edited by StephenP on Sunday 26th June 10:11

[Ken Figenus]

Gearbox over the rear axle here so no gearbox mounts where noise is? Def not exhaust mounts or a slipped U bolt touching metal/chassis etc or that lovely little alloy plate screwed under where the secondary cats would be coming loose. It could be a heatshield as mounts dont go overnight and shes still a nipper really

[Mark, sorry, I singed your frilly duster gift a bit ]

[StephenP]

Ken Figenus said:

Gearbox over the rear axle here so no gearbox mounts where noise is?

Ah, didn't notice it's a Vantage. Transaxle appears to attached to the chassis via hydra mounts/mounting brackets attached to the subframe, according to the manual.

[KnowsAnAston]

The black plug is a blanking plug for the LHD vacuum pipe to booster. They can rotate around, but they generally don't come loose.

[Ken Figenus]

Ahha! Brake servo connection. I take it there is a proper airtight bung in there and that this is just a trim bit? Thx

[Ken Figenus]

So...the rattle was...the exhaust fitter putting the thick washers for the alu plate (that sits under the centre cats) UNDER the SCREWS rather than between the plate and the body. FFS! I suspected it was the exhaust and took it back to fitter to check (3hrs of my day). Once on the ramp I apologised for bothering him, thanked him for the use of his ramp and bunged him a £20. Nice one Charlie - on top of the main dealer oner to fix too