Hi to all

I have just been checking my omega over after noticing a new hissing sound under the bonnet, This is quite loud and seems to be coming from under the pleum chamber. It is more noticeable on tick over, I can make the hissing stop when i squeeze the hose running to the ICV.

does anyone know whats causing this hissing? Sounds to me like a spilt hose or pipe of some sort i know my last 2.5 omega did not do this.

Should it hiss like it does? :-?

If i have to take the plenum off how do i go about this as i have no haynes manual as of yet. And is there any gaskets/o rings i would need to change on refitting.

Any help on this would gladly recived.

Cheers   NEIL

There are six 'O' rings under the plenum and then the seals for the manifold but it shouldn't be moving so that the sound stops when you squeeze the ICV hose, everything should be bolted up tight..

What happens if you wiggle the ICV? That has a rubber ring sealing it to the plenum and I'm wondering if that's had it and is letting in air at the bottom.

tried moving the icv thats seems  so tight no air leaking round that and plenum is bolted down tight will have to take the plenum of next weekend ands see whats what

I too, have noticed this om my Omega and have been meaning to ask exactly the same question for some time!

I have not tried squeezing the hose leading to the ICV so cannot advise any further with regard to my engine.

However, what I can say, is that I think I have narrowed the hissing down to the black ECOTEC cover on top of the plenum.  I was thinking that there may well be a seal between this and the plenum which needs renewing.

This hissing that we can hear is vacum generated.

I am hoping that a new set of seals will sort this out and, at the same time, improve economy somewhat.

So, does anyone on here know what seals are used for the plenum?  I know about the six "o" rings but are there any others?  If anyone has a list or knows any advice would be much appreciated.

They do hiss a bit at idle......its just the air rushing throught the small opening in the idle valve or the breather ports.

Could be  the sequel to the film. "Snakes in a Omega"  ;D

Cheers for that Marks DTM....  at the risk of making a stupid statement, I guess that mine is OK then and there is nothing to worry about?

iggy21uk wrote on 21. Aug 2006 at 13:35:

Could be  the sequel to the film. "Snakes in a Omega"  ;D

Ssssuch a ssssilly sssstatement....    ;D

x25xe wrote on 21. Aug 2006 at 14:40:

Cheers for that Marks DTM....  at the risk of making a stupid statement, I guess that mine is OK then and there is nothing to worry about?

well that was easlly sorted out cheers