Any tips for tracking down an air leak?

[harrris303]

Hi everyone, since the weather has warmed up and I've started driving with the windows down in my 1.9 tdi octavia, I've noticed a fairly loud hissing noise outside which gets louder as the revs increase.

 

Yesterday I got someone else to rev it so I could stand outside and try to pin down where the hissing was coming from. When they put their foot down I couldn't really hear anything particulary unusual which was strange. I've started thinking maybe the noise is much louder when the engine is in gear and driving, so can't be heard when stationary and in neutral.

This makes sense (in my head at least!) because when in gear the engine will be working harder against the weight of the vehicle so the pressure will be greater inside the engine and all the hoses etc?

 

Anyway I'm now at a loss as to how I can go about tracking down this air leak. I'm just wondering if anyone has any tips which might be helpful, or if anyone's had any similar problems in the past which they managed to solve.

 

Any suggestions gratefully welcomed! Cheers.

[Richf]

yes with a boost leak the leak will only be heard under load which you cant do when stationary , usually just a case of checking the clips etc , I suspect those mare familiar with the model will be able to point out the common areas that fail

[harrris303]

Oh right thanks very much mate. That supports my sketchy scientific thinking at least! Cheers.

 

Also I forgot to mention it's the 130 PD engine, in case that makes any difference to things.

[KenONeill]

ANy loss of power and/or noticeable black smoke? Mine once popped a boost pipe. It lost power and smoked like a bus until it was fixed. )f so, then yes you need to examine the pipes manually, from turbo to RH wheel arch and back to manifold.

[harrris303]

No black smoke to my knowledge but yes there is an occasional lack of power, but not always, just from time to time I put my foot down and it's a bit more sluggish than usual. The guy I bought it off was told by a mechanic that it had a glitchy MAF sensor which might affect the performance, so I always put any lack of power down to that.

 

I've only had the car since february so I think it's probably had the leak the whole time I've been driving it. It's quite pokey compared to my old car but I love the idea that it might have a little more power to give!

 

What should I be looking for when examining the pipes? Is it likely to be a loose connection rather than the pipe itself failing?

[YellowCar]

Quite often around where they join other sections and clipped. Also be extra observant near hotspots. They can also split along there length. In other words have a good look all over

[harrris303]

Thanks yeah that sounds like good advice! I've been reading up a little bit and it sounds like a lot of people rate highly the idea of replacing the standard clips (not sure what you call them) with jubilee clips? Does that sound like a good idea if I do find that any are getting a bit loose?

[YellowCar]

It's a great idea those single use clips are hateful things. Quite easy to damage pipes trying to get them off too so be careful. Had a fight with about 8 of them the other day, I was almost suicidal. On the smaller vacuum hoses you may consider the fuel type small mikalor type clamps with the bolt. Be a bit kinder to the small hoses. I have used the mikalor with the ears you pincer together on some small hoses. But again these are single use so be careful where you choose to use them. I kind of regret putting one of those on now but had no room for anything else and didn't trust a zip tie. God that was a long answer for a simple thing wasn't it?

[YellowCar]

By the way, I found the trick with those clamps is to get a small flathead in the ear and lever in the direction of the small tooth that holds them in place, go from behind if you pardon the expression. Keep levering and prising and eventually they'll pop undone. You'll get plenty of practise.

[KenONeill]

Thanks yeah that sounds like good advice! I've been reading up a little bit and it sounds like a lot of people rate highly the idea of replacing the standard clips (not sure what you call them) with jubilee clips? Does that sound like a good idea if I do find that any are getting a bit loose?

I could tell you what I call them, but the swear filter won't let me!

[harrris303]

Great thanks for the tips guys, those things sound like lots of fun, can't wait to get stuck in! 

[YellowCar]

Great thanks for the tips guys, those things sound like lots of fun, can't wait to get stuck in!

Not sure you'll be so enthusiastic 2 clips in, but still, have fun! Keep us posted.

[kentphil1]

Those clips are the spawn of Satan.

[giandougl]

Usually the boost pipe that's leaking is coated in oil around that area.

[harrris303]

Not sure you'll be so enthusiastic 2 clips in, but still, have fun! Keep us posted.

Haha I was being slightly sarcastic there, those things sound like a nightmare! The truth is I can see this being put off for quite a while, but I'm pretty sure I've noticed my mpg getting worse so should probably get it sorted soon.

[YellowCar]

Haha I was being slightly sarcastic there, those things sound like a nightmare! The truth is I can see this being put off for quite a while, but I'm pretty sure I've noticed my mpg getting worse so should probably get it sorted soon.

Thought so lol. Rich running you could indeed be seeking a leak after turbo. You'll find that just going round doing the clips is an effective way to check pipework, I didn't notice my split until I went to undo the pipe at the joiner. I had heard it I think but like yourself couldn't pin it down. It had a smoke test a few months ago as well. Once I've done a couple of bits I'm going to get a smoke test again as may need to rule out boost leak once again. Need to fit a new intake pipe so I'll have a sniff while I'm round the turbo as well.

[harrris303]

Ok yep sounds like a good plan. I'd best get hold of some jubilee clips! Quite daunting though. Seems like there's a lot of pipework going on under there. Most of my mechanical experience is with my old series land rover which is a very very simple machine in comparison! Giant mechano set basically haha.

[YellowCar]

They may have to be pretty small jubilees in places, may be better with fuel line clips, can get from Halfrauds usually.

[harrris303]

Thanks mate that looks like another good suggestion. I was surprised how expensive jubilee clips were after looking on ebay! Might have to take a little trp to Halfords after work.

[YellowCar]

Thanks mate that looks like another good suggestion. I was surprised how expensive jubilee clips were after looking on ebay! Might have to take a little trp to Halfords after work.

For all their faults Halfords do have a decent selection of clips and bits, won't save you much over ebay but at least it's easier to pick and choose.

[harrris303]

I find the problem with ebay for little bits is that you have to buy in bulk, which is fine if you need that many but if you only need a pair then it's a bit pointless (That said it looks like I might need quite a few haha.) Have to say I'm going to get a bit confused about which of the small lines are air hoses and which are fuel lines etc. Probably good to get that sorted first!

 

Don't suppose anyone knows off-hand what size clips you'd need for the large intake hoses? From memory I'm guessing 75mm or so but good to be sure.

[harrris303]

I just nipped out of work for 5 minutes to go and have a look under the bonnet and I think I might've found the problem. The large hose that comes out of the turbo has a pretty loose connection, which I assume is not good!

 

At the other end it is attached with one of those clips and is fairly secure, but the loose bit is connected in a different way and I can't quite see how it all fits together. It looks like the hose has a metal collar which slots into the turbo? Can anyone enlighten me?

 

Cheers.

[YellowCar]

I mean fuel pipe clips for their size and style more than anything.

Could well be your problem, do you mean the main intake pipe?

[harrris303]

Haha I'm not quite sure to be honest. After more research I've now established it might be coming out of the EGR valve? I've found a photo of where the loose connection is. If you can tell me exactly what it is then I might be getting somewhere!

 

 

The white circle is where the loose connection is, although the pipe the guy is holding looks like a different type of connection to mine...

 

[YellowCar]

Ok that's where I'm unsure, don't know those engines well, sure someone will pop along. Might be worth starting a new thread with that pic and asking.