What is the latest definitive guide to eradicate the 'mooing' noise

Hello All,

I appreciate this has been covered to death and everyone's probably sick of this topic. I have searched through an extensive archive of 'mooing' threads but many are over 5 years old and or are people speculating or saying that the have the same issue but no real solutions being stated.


I have a 2002 1.4 TDI with 111k on the clock. The noise it makes when slightly pressing the accelerator pedal is a slight 'glug' noise to me but some people call the a mooing noise. From my understanding it is attributed to the EGR Valve but from my understanding of things some people are referring to the ERG vacuum solenoid as it is mounted high up behind the dash. People are saying that the EGR valve needs to be isolated from the car body using rubber bobbin grommets or washers. But do they mean the Vacuum solenoid or the ERG valve attached to the engine?

In the past I have cleaned out all of the 'gunge' on an EGR valve (the black carcinogenic grease like stuff) and it made no difference to the efficiency or running of the engine afterwards. This was on my VW T4 TDI I also have. Also I have blanked off the EGR with an aluminium blanking plate I purchased but again this made no real difference. The EGR valve is very hard to get to on an A2 and looks like it involves removing heating ducting and many engine covers and pipes in order to get access to it so is it worthwhile cleaning the egr out? I noise if its staying open (not sure how to check this) it will effect the fuel efficiency and basically not do its job properly.

I tried taking one of the vacuum solenoid pipes off and pushing a plug into it (basically a bolt) and this eradicated the 'glug' noise but when I put it through its MOT a day later it failed as was emitting too much smoke to pass. I simply put the rubber pipe back on for the garage and then it passed but the 'glug' noise returned! This vacuum solenoid unit appears to be mounted on a flexible rubberised clip so I can't see that it will vibrate through the car body.


Another route people take is to get the car remapped but I can't really afford the cost right now and have only had the car a few months so it needs to prove itself before I treat it to such expenses! Also I just spend £360 on a new clutch and flywheel regrind!


So if anyone has any advice that would be appreciated and I hope my thread can help others experiencing the same problem taking into account that many A2's are getting on a bit more now and have lots of miles on them. Some of the threads were written when the A2 was much younger!


Thanks


Aaron
 
i am also suffering along with another member recently regarding this mooing noise. is this an easy job to fix? and do you have any photos or a step by step guide on how to do apply the bolt to the correct pipe Aaron? would appreciate it as i want to silence this problem too! ive got too many animals running and making noise in the household without adding a cow to it ;)

any help and info given is appreciated and i will also find the post from the other member who has the same issue.

cheers

cammy
 
Hi Mr Angry, I took the rubber pipe of the ERG vacuum solenoid which had a stiff black PVC pipe pushed into it. I pushed a M6 bolt into it. I wouldn't really recommend this as a long term solution as like I said the car was smoking a lot afterwards so I put it back to how it was. There must me another way and it may just mean stripping back all the items so that the EGR mounted onto the engineer can been relieved of all its sludgy gunk. But interested to hear from people who know their stuff as I'm certainly no mechanic.

Cheers

Aaron
 
For info the sole function of the EGR valve is to bleed exhaust gas back into the engine under specific load conditions to reduce NOX emissions. (NOX is colourless)
As disabling the EGR should have no effect on smoke levels I wonder if the wrong pipe has been disconnected. One possibility is the pipe to the turbo boost capsule was removed in error.
There is some info in this post (in Dutch) on how to access the EGR etc. - http://www.a2oc.net/forum/showthrea...-dismount-for-cleaning&highlight=capsule+pipe

I disabled my EGR by removing and blanking the pipe to the silver capsule on top of the body of the EGR valve assy - http://www.a2oc.net/forum/showthread.php?11079-Has-anyone-blanked-their-EGR&p=84918#post84918

The mooing noise seems to be caused by the bulkhead mounted (passenger side) turbo boost and EGR valve assy resonating, presumably from continuous pulsations in the vacuum lines. The Audi 'fix' was to isolate the assy from the bulkhead using rubber bobbin mounts.

Cheers Spike
 
i would just like to confirm that the mod done via this link http://www.a2oc.net/forum/showthread.php?20411-EGR-valve-bracket-mount-mod

i would say that mines is 90% better with a very quiet moo but no where near as bad as before! i reckon if i used the proper hose etc it would be 100%

on my mod i used a thinner plastic red (didnt have black) hose to attach the bracket. with slight adjustments it was almost gone but im alot happier :)

IMAG0206.jpg

i will post my image on this post along side the other link above.

cheers

cammy
 
Hello All,


Some great info and new links the threads I hadn't found including the thread with the 30mm dia rubber pipe being cut up and used to isolate the EGR.


From what I can establish the culprit of the so called mooing noise (sounds like a rumbling tummy or a glug noise to me) is to do with the vacuum valve solenoid fixed up to the bulkhead near the heater ducting. No noise comes from the aluminium EGR fixed directly to the engine then from what I have read. I think the idea of blanking off the pipe which links onto the EGR silver domed part might make sense and I may try that.

Thanks Spike for your info on the function of the EGR that helped me understand things better. I am still puzzled as to why the car became very smoky (black smoke) when I plugged the rubber tube coming from the solenoid device but I expect I picked the wrong one. I can see the pipe in Mr Angry's photo showing his mod with red piping. It has a breaded rubber hose about 12mm dia linking onto a smaller pvc pipe - this is the one I plugged/capped off. It made the noise go but as I said upon restoring back to how it was the MOT garage passed it with me watching.

Mr Angry glad you sorted yours out and didn't have to get to the EGR and clean out that horrible black gunk as I think I may have to do this on mine. There is lots of black oil around the EGR so maybe something is leaking on mine but some people say this is common on all TDI's'

I have other things on my mind as well now as I suspect my Intercooler has gone and reading about the dreaded 'limphome' issue with these cars. Its never ending on this A2 but I still like it but its starting to get expensive with new brakes all round and a new clutch and only owned it for 2-3 months


Cheers


Aaron
 
For info the sole function of the EGR valve is to bleed exhaust gas back into the engine under specific load conditions to reduce NOX emissions. (NOX is colourless)
As disabling the EGR should have no effect on smoke levels I wonder if the wrong pipe has been disconnected. One possibility is the pipe to the turbo boost capsule was removed in error.
There is some info in this post (in Dutch) on how to access the EGR etc. - http://www.a2oc.net/forum/showthrea...-dismount-for-cleaning&highlight=capsule+pipe

I disabled my EGR by removing and blanking the pipe to the silver capsule on top of the body of the EGR valve assy - http://www.a2oc.net/forum/showthread.php?11079-Has-anyone-blanked-their-EGR&p=84918#post84918

The mooing noise seems to be caused by the bulkhead mounted (passenger side) turbo boost and EGR valve assy resonating, presumably from continuous pulsations in the vacuum lines. The Audi 'fix' was to isolate the assy from the bulkhead using rubber bobbin mounts.

Cheers Spike



Just wandering, what is a pierburg pressure converter spike? Is this what is also known as a egr vacuum solenoid? The item which is cause vibrations and resonating ? Thanks again Aaron
 
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