2.5 Avant Quattro - suction noise from engine

Looking at buyingthis car, the one that i have seen has a strange noise that can be described as suction noise, it happens when the car is standing and you accelerate and as you let go there is a suction noise coming from the engine. Is this noise normal for this car. I havent test drove the car yet so dont know if it will happen when driving. I know my friend has a saloon 2.5 tdi and it definitely doesnt make this very obvious noise. Could it be coming from th Turbo, it like air being sucked but it is very loud.

I posted this message on HonestJohn forum and had a response from someone who worked at audi and thought it was quiet normal for these engines from his experience. Another person asked if it has a duno valve, is a dump valve the same as a vibrating damper? because when i asked for a quote for the timing chain today I was asked if the car has a vibrating damper as that would also need to be changed with the belt.

Any Help appreciated, thanks

went to see this car today, the suction noise is non existent, however it has a quiet whistling sound when you release the accelerator, which the garage owner told me is normal as its the turbo that makes this sound...

Don't know if its the same on the 2.5 Audi engine, but on the petrol turbo Volvos I've had you can hear the turbo recirc valve when you release the throttle. Works a bit like an atmospheric dump valve but dumps the boost back into the inlet system in between the MAF and the turbo.

The 2.5 tdi has a cambelt and NOT a timing chain. The suction noise you heard might have been a loose jubilee clip on one of the boost pipes, especially if there was recent work done on the car. Whistling noise when letting off the accelerator is normal and it means that the VNT mechanism on the turbo is not jammed. A full cambelt job will cost 600+ at dealer or about 500 to an independent. Its a quite involved job and i would ask for the thermostat to be replaced at the same time, toghether with a new water pump and all the tensioners/relay rollers includding the hydraulic damper. The parts alone cost over £311 on trade...See me other posts for cambelt offers for £370 all in. I work on these cars on a daily basis and i use quality parts: FULL Contitech cambelt kit, KWP/Meyle water pump(metal impeller), pump belt kit, aux. drive belt, AC belt, 5L of G12 antifreeze, profesional setting of the diesel pump and a diagnostic check. It takes about 4-5 hours depending on model. Hope this helps, Chris- o77 899 12128.