What's this noise?

[steane]

Hello all,

I wondered if anyone can point me in the right direction. My van, 1.6td, is making a noise that I am not sure how to identify where is coming from. To me it sounds like pressurized air being released, I took it to a local garage for another job and asked them to have a little look, the old guy said it sounds like a vibration and he can't see what would would cause it. I am going to stick my neck out and say nice old guy is wrong. It's air.

So it happens when I apply full throttle, which I generally avoid tbh. It happens in all gears. It comes from the engine bay and it sounds as I say like air escaping. I have had a look to see if I can see any obvious issues with the turbo pipes as this is what I suspected, nothing visual to report.

Anyone got any tips, ideas or fault finding techniques?

Ben

[lloydy]

If it happens on full throttle and sounds like air, it will most likely be the boost pipes. Just take them off and inspect them, quite easy to do

[kit]

Is it turbo whistle?

[steane]

Just remove all the pipes or any common one to start with?

What do you mean by turbo whistle?

[lloydy]

The one between turbo and inlet manifold. Turbo whistle is a noise the turbo makes, kinda like a whistling noise

[steane]

I set myself up for that one. It is not a normal turbo noise.

[Graham81]

I think a boost leak would show as black smoke from the exhaust on full load, does it feel like its got less power?
You could put a boost gauge on the turbo pipework to see what its doing.

[steane]

I have not seen any smoke despite looking out for it. It does feel a little down on power whilst it makes the noise. That is another thing that made me think turbo sort of area.

[Graham81]

Whack a gauge on the turbo boost pipework, see what the pressure is vs what it should be or get the boost pipework pressure tested.
You cant test it standing still as it needs to be under load for the turbo to create pressure.
You can get barbs to fit into the pipework then run a 4mm vacuum pipe up to a gauge.

[Rust Bucket]

Got exactly the same problem, does it sound something like chssss? and is worse at 50mph+

[steane]

As I say chsss it sounds the same and is worst at speed

[Rust Bucket]

Just been searching on the brickyard and found this http://www.brick-yard.co.uk/forum/possi ... 29302.html
scroll to the bottom

[steane]

Sounds like a possable option but I think I will check the pipes first. Don't reli want to take something off that designers put on. A lot of people, with more brains than me, will say it makes no difference but it is there for a reason. Will let you know what I find.

[steane]

Problem solved. After checking all pipes and joints for leaks with no joy, I thought it is time to follow the crowd...

Went to local supermarket and brought a nice bottle of red. Removed the cork and stuck it in the BOV. Done! No more silly air sound and I get to drink the wine tonight

Cheers for the input.

Ben