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[johny5]

Ok, back again with more questions hopefully someone can shed some light?!

On my 2.0 the exhaust was blowing, found out manifold was cracked so replaced with 2nd hand good one, along with both gaskets, after it was done it sounded better and more or less stopped the noise, it was ok for a few days.

But low and behold, after 800 miles of driving this week the noise is back! same as before, no garage can seem to trace where its coming from apart from its fairly high up near the front pipe, but this has all been replaced?! grrrr.......

Has anyone got any thoughts on this or anything else i need to check at all?

I desperatly want this noise to be gone... its seriously driving me mad.

[Broomies Mate]

Did the garage fit the replacement correctly? Torque the manifold nuts up correctly?  Was the 'known good one' really a good one?

[johny5]

Well i had a mechanic come to my house whos also a mot tester, but eventually finished it off at the garage on the ramps.

He tightened it up but didnt use a torque wrench, he said he had enough experience to know roughly torque by hand?

Also as far as i know the manifold was ok, but it was bought from ebay so who knows?

But as i say the noise did go for a couple days?

[Broomies Mate]

This isn't absolute matter of fact, but you can usually tell the difference between an exhaust manifold blow and an exhaust blow by the sound.

An Exhaust Manifold Gasket/Manifold blow will sound higher pitched than a regular exhaust blow... almost like a ticking noise.

Can you explain the sound you are hearing? (I know it is difficult to put into words).

[johny5]

Yeah i had a ticking on my old vec SRI, this dosent sound like that tho.

It kinda sounds like metal bits gettin blown about in the exhaust when under load if that makes sense? its not a deep blow noise, and when its cold its really quite noticeable and if u rev it quickly it pops?

[johny5]

Also dont know if it makes a difference but the revs sometimes stick at 1100 rpm ish' when idling. And other times normally its around 700

[Broomies Mate]

Have you seen the Engine Management Light on the dash at all?  Might be worth checking codes, see if you have any O2 issues.  Metallic rattling could mean a FUBAR cat, or center silencer.

[johny5]

Nope no EML at all, and the cat is fairly new. It isnt an O.E exhaust though so will sound different but this is blowing somewhere. Sounds like it is somewhere from the cat to the manifold but no obvious signs apart from noise whilst driving and when cold etc

[Broomies Mate]

Nope no EML at all, and the cat is fairly new. It isnt an O.E exhaust though so will sound different but this is blowing somewhere. Sounds like it is somewhere from the cat to the manifold but no obvious signs apart from noise whilst driving and when cold etc

Well, exhaust blows (and gasket blows) tend to quieten down when they get hot as the metal expands, 'sealing' the point at which air escapes.

To be honest, your best bet is to investigate closer and work out where the leak is.  Until then, we are just clutching at straws.

One final point though.......... I'm wondering if the guy used some exhaust paste which has literally blown out leaving a void?

[johny5]

Thats the thing, it has had close inspection although the front pipe hasnt been actually removed from the car to be looked at properly.

He didnt use any paste, i did suggest it to him but he said you shouldnt need any.

[Broomies Mate]

Thats the thing, it has had close inspection although the front pipe hasnt been actually removed from the car to be looked at properly.

He didnt use any paste, i did suggest it to him but he said you shouldnt need any.

Some people hate the stuff.  I ALWAYS use exhaust paste when fitting exhaust components.  Doesn't explain your problem though as it sounded perfec for a while.

[PhilRich]

It could be a warped manifold, & as for the bit about not needing to torque to correct values, that's just silly if you think about it! I bet if you go around the manifold with a torque wrench you will find at least one or more nuts not tight enough & hopefully the others not overly tight so they can be redone without the need for new studs or nuts

[Kneepad]

You could have someone briefly block the tailpipe while you have a look, that bit of xtra pressure might  just force the leak to expose itself.

[M4DMATT]

You could have someone briefly block the tailpipe while you have a look, that bit of xtra pressure might  just force the leak to expose itself.

Thats how i found my leak, it blew all of the rust out of the hole 
I reckon its a manifold bolt come loose as it wasnt torqued up correctly.