[Audi A3/S3] Dead Turbo - opinions greatly appreciated!!

[macperc]

Hi,

You might have noticed a couple of my earlier posts - my S3 is poorly

The symptoms are - rattling (sounds like head) from tickover until engine speed drowns out the noise. This can be heard in or out of gear but mainly under load eg manuevering in low gears it is most obvious.

In addition it's using quite a lot of oil, feels low on power and quite often stalls when the clutch is dipped while driving - it will often also immediately stall when first started in the morning. Vag com showed MAF, Coolant temp sense and possibly Lambda.

From reading posts here I assumed the problem was the cam belt tensioner + valve stem seals + coolant level sensor.

The car has been to see two Audi specialist - the first wasn't sure of the problem but suggested a new head was needed - 1200quid

The second specialst I have seen today suggested the following leading to all the above problems:

Worn turbo bearings.....this apparently leads to too much oil being dragged into the turbo. This oil is getting on to sensors such as MAFF and Lambda causing incorrect readings which causes the rev problem. Oil is forced into the engine which cause the knocking noise due to detonating(????). Loss of power is obviously the other symptom of a worn turbo.

Can anybodythat knows what they are talking about please tell me if this sounds in any way plausable??

My doubt is the knocking noise is heard mainly at lower revs like pulling away from a junction, sureley the turbo doesn't run before 1700 ish revs so how could this be causing the noise.

Sorry for the horrendously long post but any advice would be appreciated!

Thanks,

James

[jpgibson]

not that i'm an expert, but perhaps the dreaded coilpacks are on their way out. my s3 has 50000km, and just had major service- with the extra load from new plugs , it almost stalls when cold ( this is improving), and initially felt like it was on 3 cylinders. I cant see how oil can get from the turbo to the MAF- given the MAF is before the turbo.what's quite a lot of oil- they are known for using a bit .as with anything, its better to try the cheaper things first- you dont want a new head/turbo, then find the symptoms still there.

good luck

[slol]

If vag com is telling you the maf and temp sensor are gone

its not lying ,both are common failure parts,not suprised it runs like a bag of shite.

When temp sensor is faulty it overfuels because it thinks its always cold.

With the maf sensor gone it goes into limp mode and you wont get much if any boost from the turbo.

If your turbo is faulty and letting oil past into the pressure side of the system it may get onto the maf and ruin it.

[s3ollie]

I had problems with my s3 - hesitation and joke to drive. changed the MAF and all was fine again. You can get them of ebay for around £50 but are about £100 exchange from audi. I would try this first.

Also i think it is possible to get oil from the turbo to the MAF because the diverter valve recycles the boosted air back into the airbox - i think, so it is poss for the oil to get on the MAF. I not an expert but i'm sure somone will correct me if i'm wrong!

[Paul]

DV recycles air back into the intake , but after/ down stream from MAF

its not likely to contaminate the Maf as its on a verticle drop/inlet.

~~~~~~~~

Here is a Turbo intake pipe, Albeit a Samco replacement.

It sits vertical from Airbox. So any carry over of oil should be sucked/blown back to turbo.

The two pipes not marked

This version is for cars with ESP, so one of the pipes will be for ESP take off,

The other iirc for crank case breather

from memory I cant remember which is which

[macperc]

I have changed the MAFF and it was covered in oil internally- power improved for a couple of days but now has dropped off again I guss because its again soacked in oil.

What I'm more worried about, does it sound right that the mechanic has now told me that the turbo is pulling the oil off the head and so causing the rattling noise which he says is tappets running dry of oil??

Cheers

[s3ollie]

i cant see it my self mate - id get a second opinion. the oil pump runs at a very high psi/bar and would surely be able to handle what must be a tiny leak in the turbo. i cant see it will afect the pressure to the rest of the engine. i could be wrong though.

[blix]

have you tried an oil pressure test just to make sure

[macperc]

Sorry what will the oil pressure test tell me? I know the engine is using oil - will this determine where the oil is being used?

[s3geezer]

I can't see how having a screwed turbo would make the car drink loads of oil, but I'm no mechanic.

How are you getting on with the poorly motor, macperc?

[davebgsi]

Because turbos work at such high temperatures/rpm they have oil in them to lubricate/keep them cool, which is fed through a pipe from the engine into the turbo and back into the engine again. This is why before switching off a turbod car you're meant to let it idle, to let the turbo 'cool' therwise red hot oil is sat inside the red hot turbo; 'cooking' it.

When a turbo's oil seals are damaged, the turbo leaks the oil into the airflow within, this then gets passed into the engine. This is generally seen (on idle) by blue smoke coming out of the exhaust. Turbo oil seals are generally damaged by misuse of the turbo (not letting it warm up/cool down properly).

The MAF shouldn't be getting oily, unless the recirc valve dumps its air back into the inlet before it (which I don't think it does). If you took off the top air hose on ur inlet, take a look inside and see how oily it is. The more oil - the worse state the oil seals will be in.

If you get blue smoke under hard acceleration/engine coasting then the problem is more likely to be worn piston rings or stem seals.

Even if the oil seals in the turbo were almost non existent, it would never take enough oil away from the lifters within the engine to the extent that they would tap.