My audi a3 2.0 tdi has a siren noise when driving it.

STOP the engine immediately !!! There is an oil pump failure of 2.0 TDI engines !
Remove the oil pan and the oil pump & balancer shafts assembly.



Either the shaft driving the pump from the balance shaft rounds off or the balance shaft drive gears eat themselves.
The same issue ... low oil pressure warning light, noisy rattling engine, and the turbo has gone. Diagnosis: oil pump balancer shaft assembly ...




Many 2.0 TDI engines show excess chain noise and wear anywhere from 50,000-100,000+ miles. Cars have broken the chains/tensioner as low as 65,000 miles. This is just a range of cars that have been reported, diagnosed, and repaired. The actual statistics on dealer repairs or failures is unknown and I've heard cars over 100,000 miles that, in my opinion as a non mechanic (most mechanics wouldn't recognize this sound and problem either), aren't noisy. From what has been reported, noticeable noise/chain-tensioner wear/greater risk of breaking is around 60,000-150,000 miles. Your case may vary. The most obvious symptom is a rattling loose noise from the oil pan. Unless you listen to a Passat TDI with a tight chain and one with a loose chain, it's hard to describe the difference other than rattling chain noise.
The reason the gear drive oil pump modification was started is because a few mechanics who specialize in TDI have seen many worn oil pump chains/sprockets/tensioners. There will always be a few defective parts that come off the assembly line and all mechanical components like chains wear out sooner or later, but in my opinion, the failure rate is abnormal considering the number of Passat TDI sold versus the number of reported oil pump failures. This does not necessarily mean that every or even most Passat TDI will have this problem, just that the reported failure rate is high enough to consider this part a design failure. Nobody, not even VW-Audi knows the average time between failure for these parts and the percentage of cars that will have this problem, but they changed this design and if you want to not have this specific failure, the only sure way is to swap to the geared module.

The serpentine belt diagram for 1999 Audi A4 1.9 TDI:


CS = Crankshaft
F = Fan pulley
Gen = Alternator
T = Tensioner
AC = Air Conditioning
PAS = Power Assisted Steering


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Audi A6 2,5 TDI 5 cil is a great car. The engine is one of Audi's most tested engines. But models before '96 will rust quite a bit, if you dont look af it. So look for rust and be sure that the drive-belt is replaced in time.

Just a guess.. could be bearings of (external) belt castors squeaking when hot (= dry). What is the mileage? May need to replace a pulley or so...

I had something like this once with the water pump of my 2,5 TDi and I replaced the pump preventively ($120 I think), problem was solved.

More than likely the fuel pump. This may sound stupid but take something and give your gas tank a bit of a thump. What year is the car?

i have no dash lights coming on so carn't stat it, i drive an 2004 sportback a3 tdi

Check the idler and tensioner pullys for your serpentine belt. I suspect the whining noise heard earlier was due to the fact one was getting a bit stiff or rough turning. When you gave it that extra fuel, the sudden load may have finished it off. Sometimes they lock up, and sometimes they fall apart. Check those items first.

hi,i'm ck .my audi c5 2.4 model 2001, when put on D while driving, it go to neutral?