Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: Raymond on 13 May 2010, 15:55:11
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Hi, I posted before about a high pitched sound. I put the car in today to get the gearbox serviced thinking that this was the cause of the sound I was hearing. When driving around normally I don't hear anything, if I put the car into sport mode and give it the lead foot when it gets to around 4000rpm this strange sound happens until it changes gear. Is this the multi-ram air system as someone told me. It does sound kind of airish but is quite high pitched, someone said the multi-ram sounds like a turbo but this doesn't. Can someone describe what the multi-ram sounds like?
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Sounds like you might have a leak on a vacum pipe or something.
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The sound doesn't appear when the car is in neutral and revved, thats why I thought it was to do with the gearbox/diff.
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Scratch the last comment. I have just been out in the car and it only really does it when you put the loud pedal to the floor, in gear and neutral. So I'm thinking it may be the Aux belt needing tensioned or something similar?
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Scratch the last comment. I have just been out in the car and it only really does it when you put the loud pedal to the floor, in gear and neutral. So I'm thinking it may be the Aux belt needing tensioned or something similar?
One way to find out mate is to remove the Auxbelt start the car and see if the noise has gone? don't run for too long though as your water pump runs off the auxbelt.
You can also spin the Auxbelt Tensioner Pulley, Alternator, Water Pump, Air Con Pump to see if you can hear any noises or dry bearings :y
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given the multi ram seems to change the power delivery at 4k rpm i think its highly likely that the vac system has a leak. There is no audible sound to be heard from the multiram/vac system in the cabin.(edit) not under normal operation.
However the other checks mentioned are also worth doing, even if its just to eliminate other possibles.
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Thanks for all the help guys. There is no drop in power and the car is running as sweet as a nut, thats why I don't think it is a vacuum leak as this would have some effect on performance would it not. Spoke to a mechanic friend tonight and he is 99% sure it will be the aux belt,
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mine did it and was the egr valve to do with cutting down emistions in my case was the pipe to it
dint affect any engine running so i was told and found
can make idel a touch ruff they say
make a nice whistling when you really stamp on loud pedal
ill bet it is that
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Think I have sourced the problem. When looking at the engine from the front the top right pulley on the drive belt (A/C Compressor I think) it sounds as if the bearing is a bit dry.
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Nope that didn't sort it either. This is driving me insane!!! It is as if the acc pedal has 3 positions, amble about, medium pickup and gooooooo. On amble about there is no sound, on medium pickup you hear it just before it changes gear and if you press go it drops a gear and makes a racket. It almost sounds linear, it doesn't get louder or faster with speed. So I am now going to try the vacuum pipes. How many are there and is there any that are prone to failure or disconnection during maintenance. Is it the small black pipes going around the engine?
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When looking at the engine from the front the top right pulley on the drive belt (A/C Compressor I think) it sounds as if the bearing is a bit dry.
power steering pump :y :y :y
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Nope that didn't sort it either. This is driving me insane!!! It is as if the acc pedal has 3 positions, amble about, medium pickup and gooooooo. On amble about there is no sound, on medium pickup you hear it just before it changes gear and if you press go it drops a gear and makes a racket. It almost sounds linear, it doesn't get louder or faster with speed. So I am now going to try the vacuum pipes. How many are there and is there any that are prone to failure or disconnection during maintenance. Is it the small black pipes going around the engine?
yes. Usual places to check are rear multi ram, pipe often missed when refitting plenum, front connector on front reservoir on air intakes by alternator pulley, and the main large vac pipe from plenum 17 mill nut on pass side, undo it, pull large vac pipe off plenum and see if its worn through from rubbing on the adjacent air con pipe.
These are known usual leak areas. Ultimately though, may well need to check the whole system. hth
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at a guess though, i'd start rear of plenum as i think thr front multiram causes loss of power below 4k, and that the rear multiram deals with revs above 4k which seems to be when the noise occurs, or along those lines anyway.
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Thanks for the replies, I will have a look tomorrow and see how it goes.
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Had a look but cant see anything obvious, its a bit tight at the back of the engine. Is it better to take the plenum off? I did notice that the four pipes going into the rear of the plenum had no clips on them.
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Had a look but cant see anything obvious, its a bit tight at the back of the engine. Is it better to take the plenum off? I did notice that the four pipes going into the rear of the plenum had no clips on them.
it wont be obvious, in order to rub through it needs to be rubbing on something else, so by definition there will be something covering the hole if there is one.
As said, remove the main vac feed from plenum on pass side and check its not worn through by the ac pipe by bulk head. Get the engine running and feel your waylround the pipes litening for hissing. Role your sleaves up and get in there. Try reving the engine from the engine bay, check the multirams move, listen for the noise.
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Took off the main vac pipe, seems okay. Checked the pipes on all the T-pieces etc, all seem okay. How do I rev a DBW car from under the bonnet? The sound comes on constant when accelerating and if the car kicks down it is higher pitched, if I lift of the acc pedal then the sound goes then returns when I press the pedal again so it certainly sounds like a vac leak. Where would i be able to buy the pipes, I know I could get them from Vx but they are likely to be expensive.
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Does anyone know the size of the vacuum pipes on the Omega? I think I might replace all the ones that I can, one at a time to see if I can find this leak before I end up in the asylum. I just hate knowing there is a problem with the car and not being able to source it....aarrrggghhhh.
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A quick update and hopefully some advice. I have changed all the vacuum pipes I can get to, from both vac tanks and the connecting runs. There are two that I cant get to at the moment and I was hopeing someone knows what they are for. There is one at the back of the engine that goes straight down the back and my hand are too big to see where it terminates, and also the one that runs under the plenum. Does anybody know where these go?
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When modifying my Y26SE to X25XE loom and intake I noticed that the vacuum hose came from the FPR. Not 100% sure if that's correct, but that's how mine was connected. It lines up quite nice with the FPR too.
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Cheers mate. Is that the one under the plenum or the one that goes down the back of the engine?
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Mine came from the FPR, under the plenum and into a rubber hose joint under the throttle. Not sure what it was connected to after that as it was partially dismantled.
On later models it could also be from rear multi-ram valve to a tee with front valve and vacuum canister. At least mine was connected to the FPR.