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[Big_Al]

Been trying to search out previous posts for this but no luck. so appologies if it has been asked before.

When starting my 3. 0 facelift  from  cold it sounds like quite a loud exhaust blow from somewhere on the nearside of the car.  After  about a minute - it stops & is quiet as normal . It seems to co-incide with the revs dropping as the engine warms.  Does not do it when engine is started warmed up :-/ :-/

Any ideas where to look first ? :-/ :-/ :-/

TIA   Al

[Bent valve]

Been trying to search out previous posts for this but no luck. so appologies if it has been asked before.

When starting my 3. 0 facelift  from  cold it sounds like quite a loud exhaust blow from somewhere on the nearside of the car.  After  about a minute - it stops & is quiet as normal . It seems to co-incide with the revs dropping as the engine warms.  Does not do it when engine is started warmed up :-/ :-/

Any ideas where to look first ? :-/ :-/ :-/

TIA   Al

Under the bonnet

[amba]

Al.

If it makes that noise from cold it points to somethning not making a metal/metal seal...if it goes when it warms up it point to the metal expanding and making a seal.

If is the n/s my first thought would be exhaust down pipe gasket to manifold ,especially if the exhaust has been undone or replaced by a speedy fit centre as they tend to use pretty crap gaskets.It might be worth getting a socket on long extension bar from below and seeing if both the copper nuts are nipped up to the correct torque.If you feel keen you could always drop the down pipe from the manifold and replace the circular gasket seal with a proper GM one.

Also worth having a good look around as you may have the start of an exhaust manfold gasket failure or broken stud,but that would also give you a clicking noise from the followers which you haven,t mentioned.

[Big_Al]

Been trying to search out previous posts for this but no luck. so appologies if it has been asked before.

When starting my 3. 0 facelift  from  cold it sounds like quite a loud exhaust blow from somewhere on the nearside of the car.  After  about a minute - it stops & is quiet as normal . It seems to co-incide with the revs dropping as the engine warms.  Does not do it when engine is started warmed up :-/ :-/

Any ideas where to look first ? :-/ :-/ :-/

TIA   Al

Under the bonnet

Ah     maybe I need to post that I have checked all the obvious exhaust joints

[Broomies Mate]

Leak in the SAI system?  :-/

[amba]

Worth checking the three plugs on that side to make sure none are loose.

[millwall]

mine does the same al  i have a small crack in exhaust manifold  maybe worth a check   

[Big_Al]

thanks for replies so far.  will have another close look.

just been outside again to listen.  lying on ground by n/s near front   wheel & passenger door I can hear a blow - but nothing from in engine bay with bonnet open. Problem is it only does it for less than a minute on initial start up from cold. will have to leave for an hour or more before it will repeat.    weird :-/ :-/ :-/

  SAI   leak - where & what am I looking for there?

manifold / down pipe leak -  OK on that one

[Broomies Mate]

If it were the Secondary Air Injection, you'd hear it under the bonnet. 

Sounds like a downpipe to middle section joint problem.

[amba]

If it,s the down pipe to the mid section you may be able to see a tell tale of soot if its been doing it a while.

Manifold end will be harder to see but that would seal up pretty quickly,which is what you are indicating by sound going after a minute or so,as that gets very hot in a short time.

[albitz]

Exhaust manifold gasket.