passat tdi turbo noise - planevw
I have just bought a 98 passat tdi 110bhp with 145000 miles on the clock. It has a noticable high pitched noise coming from the turbo when on boost that sounds like an air leak. I have been told ithas a variable vane turbo fitted which is operated by a vacuum pipe. If you remove this pipe the noise goes away. I have checked the impellor of the turbo and there is no wear on the bearings and the car produces no abnormal amounts of smoke. The noise is more apparent in the lower rev range. Has anybody got any ideas?
passat tdi turbo noise - DL
Without actually 'sampling' the noise first-hand it is very difficult to give a judgement here.....

It might just be normal noise; on the other hand it might be the signs of impending failure or it could be simply a pinhole in a hose or another pressurised component - I don't know.

My 110TDi Audi A4 has a slight whistle under load, certainly not a high pitched noise, anyway.

passat tdi turbo noise - planevw
It isnt the normal noise that you would expect from the turbo. Wondering if the cat may have collapsed and causing a back pressure on the turbine. Has anybody else hd similar experiences with cat failures
passat tdi turbo noise - JohnM{P}
Had cat failures on both A4 110Tdi company pool car (60k+ S-reg) and my own R reg 110 Passat (125 ish k)k. Audi was rattling badly when I gave it back for the company and leasing company to argue as to whether to repair it or send it to auction; my own Passat went quickly from rattle to blocked exhaust - no power, 35mph max. To address your question, neither affected the sound of the turbo. (
I've driven 300k miles in 5 different 90 and 110TDi VW/Audis - the only time I've heard a turbo whistle is in the first mile from cold)
passat tdi turbo noise - madf
Cat failed on my A4 110TDI after 70k miles : rattle due to (badly welded) baffle plates .. a known VW/Audi failing. No effect on power: just a rattle at idle.

If you have a whistle you may have an induction leak .. check all the pipes attached to the inlet system including the servo.. you may have a split hose ...(visual inspection must include twisting /bending each pipe to check for hidden splits..)

passat tdi turbo noise - bertj
This doesn't sound normal. There's been five VW tdi/pdi's in our family - never heard a high pitched whistle. Look for an induction leak. The fact that when you remove a pipe the sound goes away suggests that it's not a fault with the actual turbo.
passat tdi turbo noise - Craig_1969
I was cruising at 95mph last night when there was a surge in power, followed by turbo failure?? I have a VW Passat TDI 110. V plate 100k.

Now the car surges/hunts whilst cold, and when warm seriously underperforms. I get a sound a bit like someone hoovering under the bonnet.

I noticed that this thread was uncomplete and it sounds just like my problem, bertj did you find a resolution?
passat tdi turbo noise - Craig_1969
Turns out that my noise wasnt a broken turbo as the breakdown guy diagnosed, it was an intercooler pipe which was loose. My garage mechanic also thinks the maf has had it.

passat tdi turbo noise - DL
A fairly common problem as the miles mount up on diesel cars - the oil inside the intercooler pipes makes them go 'soft' and then they go pop.
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