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[Raymond]

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?

[Mr Skrunts]

Sounds like you might have a leak on a vacum pipe or something.

[Raymond]

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.

[Raymond]

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?

[Darth Loo-knee]

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

[feeutfo]

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.

[Raymond]

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,

[dragonlord]

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

[Raymond]

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.

[Raymond]

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?

[Andy B]

....
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     

[feeutfo]

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

[feeutfo]

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.

[Raymond]

Thanks for the replies, I will have a look tomorrow and see how it goes.

[Raymond]

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.