P38A excessively noisy exhaust

[kermit_rr]

Ok i think I'm having a mental block here, for ages i thought all the noise was coming from the middle box as it's been leaking for ages.
Finally got round to replacing it and fired up expecting range rover quiet burble, but not really much difference.
I've stuffed rags up the tail pipes to try and isolate any leak in the system but can't find any leak anywhere. At idle it sounds pretty good, but hit the throttle and it's like the exhaust manifold are blowing at the gaskets, but I'm pretty sure they aren't.
Noise is definitely from the front half of the system.
I'm obviously being stupid as usual!! What am i missing?

 

[Mark Piercy]

Did you do the revving up with the tail pipes blocked as well?

 

[kermit_rr]

I did

 

[Mark Piercy]

Next thing is to let it run blocked and go around the manifolds and work your way back along the system... Poopy job but it should reveal you dilemma my good man?!

 

[kermit_rr]

It's kinda hard revving the engine while underneath lol

 

[Henry_b]

I bet you my left nut it is the manifolds or a leak at where the mani connects to the downpipes/cats

 

[kermit_rr]

It does sound like manifolds but when i rev it with my head under the bonnet, you only hear normal engine noise

 

[Henry_b]

It does sound like manifolds but when i rev it with my head under the bonnet, you only hear normal engine noise

Get yer other half to dance on the skinny pedal while you scoot around underneath

 

[kermit_rr]

Get yer other half to dance on the skinny pedal while you scoot around underneath

That's a big assumption right there

 

[Henry_b]

That's a big assumption right there

Process of elimination..

Check the rear intermediate pipes, if they're fine move on to the centre muffler and then the downpipes and then the manifolds etc etc

A fast idle stick works wonders,

 

[kermit_rr]

I'm certain is North of the middle box, I'll have another looksee tomorrow. I thought sustained high revs were a box killer?

 

[Henry_b]

I'm certain is North of the middle box, I'll have another looksee tomorrow. I thought sustained high revs were a box killer?

Holding it at 5 grand in neutral or park wouldn't do it any good.

You're looking to only raise the idle up to around 1800rpm.

 

[Grrrrrr]

It does sound like manifolds but when i rev it with my head under the bonnet, you only hear normal engine noise

Strip of bog paper on a stick and see where it flutters?

 

[kermit_rr]

Strip of bog paper on a stick and see where it flutters?

You mean take the serp belt off first?

 

[Marshall8hp]

Or the fan as a better alternative, then you at least have a water pump running.

 

[Mark Piercy]

Or have someone carefully stop the viscous fan while you investigate, inspector.

 

[kermit_rr]

Or have someone carefully stop the viscous fan while you investigate, inspector.

Carefully!?

 

[Mark Piercy]

Carefully!?

Blindly....

 

[tomcat59alan]

Strip of bog paper on a stick and see where it flutters?

In the pan?

 

[tomcat59alan]

Blindly....

Fingerlessly.