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Omega Owners Forum › Omega Help › Omega General Help › under bonnet hissing

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under bonnet hissing (Read 1351 times)

nigsey1600e

Junior Member

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Posts: 101
leicsester
Gender: male

under bonnet hissing
20. Aug 2006 at 12:05

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? Huh

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

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rpont

Intermediate Member

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Posts: 272
Tadcaster
Gender: male

Drives: 97 2.5v6 CD Auto

Re: under bonnet hissing
Reply #1 - 20. Aug 2006 at 12:36

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.

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nigsey1600e Junior Member Offline Posts: 101 leicsester Gender:	Re: under bonnet hissing Reply #2 - 20. Aug 2006 at 12:53 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
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x25xe

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Posts: 925
Hayes, Middlesex
Gender: male

Re: under bonnet hissing
Reply #3 - 21. Aug 2006 at 10:56

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.

1998 2.5 V6 Omega CDX, Leather and Electric Pack!

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Marks DTM Calib Administrator Offline Ex Member Posts: 25671 Northern Hemisphere Gender: Drives: Astra J, Mum Bus, Dexta Tractor, 108 DMU wip	Re: under bonnet hissing Reply #4 - 21. Aug 2006 at 12:01 They do hiss a bit at idle......its just the air rushing throught the small opening in the idle valve or the breather ports.
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iggy21uk Omega Knight Offline Omega Spotter - tats gone tanning Posts: 1148 Berkhamsted - Herts Gender: Drives: Omega 2.5 Elite 1999	Re: under bonnet hissing Reply #5 - 21. Aug 2006 at 13:35 Could be the sequel to the film. "Snakes in a Omega"
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x25xe Senior Member Offline Avater removed due to size Posts: 925 Hayes, Middlesex Gender:	Re: under bonnet hissing Reply #6 - 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?
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Markjay Omega Lord Offline Posts: 5452 London Gender:	Re: under bonnet hissing Reply #7 - 21. Aug 2006 at 14:52 iggy21uk wrote on 21. Aug 2006 at 13:35: Could be the sequel to the film. "Snakes in a Omega" Ssssuch a ssssilly sssstatement....
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nigsey1600e Junior Member Offline Posts: 101 leicsester Gender:	Re: under bonnet hissing Reply #8 - 21. Aug 2006 at 16:29 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
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