Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: Stig on 04 October 2007, 12:48:14

Title: V6 2.5 Sounds like blowing manifold when cold?
Post by: Stig on 04 October 2007, 12:48:14

Hi all  - has anyone got any experience of this? I've had  a couple of exhaust problems  which this  forum has helped sort out.  I now have a completely new exhaust system.  

However, when the  car starts from cold it sounds to growly for a smooth V6.  Sounds like a blow,  but as the  car warms up to operating temp, the noise goes and it sounds OK,  but I don't think that's  right.  Could it be a  gasket, or manifold.  This is 2001 V6 2.5 and sounds like its on the lower left (viewed from front) passenger side. Thanks Stig :-?

Title: Re: V6 2.5 Sounds like blowing manifold when cold?
Post by: sounds2k on 04 October 2007, 14:30:58

sounds like manifold gasket - a common problem - had the same on my first (T-reg) omega ... never did bother me enough to fix it before selling though  ::)

Title: Re: V6 2.5 Sounds like blowing manifold when cold?
Post by: Darth Loo-knee on 04 October 2007, 17:18:04

My exhaust manifold gasket "Ticks" from cold but goes quite when warmed up a bit..  :)

Title: Re: V6 2.5 Sounds like blowing manifold when cold?
Post by: Snapper on 04 October 2007, 17:26:18

I've had this on a past 2.5 V6 and was told by a mechanic friend that the cars are known for it ........ seems that the exhaust manifold is known to slightly miss form ( warp) and then begins to blow the gaskets . When it warms up the expansion of the metals hides the gap and all is well,  it was also suggested that replacing the gasket is only a temporary fix.

Title: Re: V6 2.5 Sounds like blowing manifold when cold?
Post by: Darth Loo-knee on 04 October 2007, 17:39:37

Quote

I've had this on a past 2.5 V6 and was told by a mechanic friend that the cars are known for it ........ seems that the exhaust manifold is known to slightly miss form ( warp) and then begins to blow the gaskets . When it warms up the expansion of the metals hides the gap and all is well,  it was also suggested that replacing the gasket is only a temporary fix.

I maybe wrong and if I am someone well be along shortly to put me right, but I thought the Gasket is what has been changed by Vauxhall as that was the problem not the actually manifold..

Title: Re: V6 2.5 Sounds like blowing manifold when cold?
Post by: Dazzler on 04 October 2007, 21:00:20

Yep, does sound like the manifold gaskets. You probably still have the old style gasket fitted, they have been modified now so that they last longer ;)

Title: Re: V6 2.5 Sounds like blowing manifold when cold?
Post by: Sir Gingerlot on 07 October 2007, 01:38:00

One other gasket to check is the one that connects the front pipe to the manifold. This is alot easier to replace and may be done by your local exhaust centre. My 2.0l only cost £18 to change and solved the intial start up blowing that I had left for over a year.

Title: Re: V6 2.5 Sounds like blowing manifold when cold?
Post by: Stig on 08 October 2007, 20:37:52

Thanks to  all members who offered suggestions.  I've followed  some up.  Seems you have to be careful with aftermarket/pattern exhausts. Leson here is  to buy the VX bits I suppose.   I think we've pinpointed the front blow to be a gasket type on the manifold to downpipe - looks like there was a change after '99 and mine's an 01 and has a different type of gasket there -I checked that with VX and I'm going to follow that up, before I go for the manaifold gasket - that's a 4.5 hour job...

The real shocker was that the nearside middle box fitted by Kwik Fit is of a different type to the offside (they did both)and this nearside box has failed in two weeks.  It's warrantied so they're changing it for the same manufacturer as the offside. That will at least make the car sound right!