Engine resonance

[TheMadhatter]

I am not sure if I have a problem or not I have just noticed something that I had not before and was wondering if it's normal and if anyone else has noticed this.

Around 1600 - 2000 rpm the engine not of my 130Tdi is quite "boomy" and the engine vibration is at it's worst. It's not particularly obtrusive in the front of the car. However the other day I sat in the back and got my long suffering Dad to drive me round so I could find the source of a rattle in the head lining.

This is when I noticed how bad this boom is if you sit in the back. It's loud and distracting and I would not like to travel far in the back of my car.

Is this normal for the 130 ? or is something some where amiss? Has anyone else noticed this?

I might just be nit picking but you know how it is

[bobmac892]

Madhatter

Do you have both of the front engine covers on the underside of your car. When I first got my '03 TDI Estate the front cover was missing which caused the rear one to be blown down onto the road. Anyway a ******* replacement at £120, noticeable quietened the engine noise.

I was advised of the tow cover the front one is more important than the rear one and I was surprised the diference. The cover does have a lining of expanded foam to supress noise.

I know the fixings for these are a swine to re fix after work and are often not properly attached by garages. I had a bit of work done just prior to my one failing.

These are also available on eBay for alot less but the ones I saw (after being mugged at the *******) didn't have the foam lining.

Failing this I have noticed an echo when one the rear windows isn't fully up.

Hope this helps.

[TheMadhatter]

Both engine covers are there.

It's something I eihter suddenly noticed or its not been there before. When your sat in the back it's that sort of low frequency noise you get if you leave a window open. My instant reaction was that I might have a leak in the exhaust but there is no obvious signs of this from out side the car. It concides with any rattles I have as well (head restraints and that bloody bit of head lining) the engine is nice and smooth at idle or higher revs, could just be the cold weather and engine taking longer to warm up. I am going to try and monitor it I have 6 months left on the warranty.

[vincentbob]

This is quite possibly the air duct that connects to the air filter housing, its a common problem and always seems to make itself heard at the revs you mention.
I've had it with mine, and I have heard of several others.
The duct clips into place and in time becomes a loose fit; the cure is to hold it in position with some tape.
To test, get someone to hold the engine at the revs that make the noise, you can then hold the duct and see if its that.

[TheMadhatter]

That may be it. I have done this but its not the the box/vibrating on the rest of the car its the air resonating in the intake system.

There is some air escaping from the junctions and this is making a booming noise !. If I squeeze the ducks the noise changes. I will try and seal these and see if it makes a difference.

[TheMadhatter]

I tried the tape on inlet pipes trick but that had no effect. Just posted this on a similar thread, but for those who have helped me on this thread here it is as well

I will try the sponge trick tomorrow. I am just trying to work out if this a car trait or something dying. To aid this and nerdy as it is, here are the sounds my car is making.

In the front
http://www.madhatmtb.pwp.blueyonder....3/MVI_2584.mp3

In the back

http://www.madhatmtb.pwp.blueyonder....3/MVI_2585.mp3

From under car

http://www.madhatmtb.pwp.blueyonder....3/MVI_2586.mp3

I will get one of it under load driving later. I want to have some idea of what it is rather than "just a booming noise"

[TheMadhatter]

I have done the sponge trick today and it has had no effect on the booming but has silenced a growling noise I got under heavy load.

One question for the techs though. The EGR valve, when is it supposed to operate/move. I was watching it and listening to the engine as some one else steadily increased the engine revs and then rapidly changed the revs and it never moved. I checked with the engine off and it moves freely by its self.

[stonedagain]

I had a similar growl/resonance on my Passat tdi 130. Tried the usual suspects eg intake ducting air filter, engine cover etc to no avail. On Sunday, I checked my pollen filter, & after refitting the cowl I went for a drive & immediately noticed the elusive growl had gone! When I got home, I had a look around under the bonnet to try to discover what I had done to kill the dreaded growl. When I examined the cowl, I noticed some marks on the battery cover & on the cowl, plus some matching marks on the underside of the bonnet. It looks like there is only a very small clearance between the bonnet & cowl, which can allow them to vibrate against each other at certain engine rpm if the cowl is not perfectly aligned, causing the dreaded growl. I fitted two short pieces of felt tape to the areas of the bonnet which were marked to prevent future problems. The car is now a lot quieter than it ever was.
Hope this helps others to kill their growl too!

[TheMadhatter]

I will have a look at that to stop the growl. However the booming throaty noise is slowly getting worse so I strongly suspect one of my silencer/mufflers has gone. It looks like the original vw exhaust so after 80.0000 miles I would not be surprised. Its quite hard working out which bit though.

[TheMadhatter]

I had the centre silencer replaced to day and that has got rid of the growly noise I could hear, but has not had much effect on the booming.

Which is kind of what I expected one part of the noise sounded like the exhuast and the car is quieter now inside. However that booming noise has been getting worse over the last few weeks. You can feel the car vibrate. It's most noticeable if your on the motor way in 6th and you slow from 70, nice and smooth to 60 where you get the booming and vibration.

Anyone got any ideas ?

Between the water leaks, the begginings of an oil leak around the crankshaft oil seal and this exhaust my love affair with this car is slipping. Not quite how I expected my VW owner ship to go.