Non corrado related - Audi TDI (possible turbo)

[herisites 0]

Hi guys,

 

Just want to pick a few brains really. I am currently using my old man's audi (2.5 v6 tdi) as my car is finally in the body shop. Quick story of it recently, it had been off the road for ages, we tried starting it but it didn't want to know. We gave it to a diesel specialist and they found the problem to be a corroded relay for the ECU due to the drain plugs being blocked in the scuttle tray (common problem apparently, drain plusg now removed so has lots of drainage!). They got it all running perfectly fine but it needs an ECU reset from Audi only to get things like electric windows back working.

 

Anyway it's been running fine. I have been driving it past 2 days and noticed that when it got up the revs it lost power and backed off and then it would come back in again. I thought it was the ECU problem, it needs to be reset so must be a limiter or something kicking in.

 

Today however on the way to work it was running normally, I turned off down a country road and opened it up a bit (not thrashed it at all) but it was hardly going anywhere. All of a sudden there was a pop, the turbo went really loud and there was white smoke coming out of the exhaust (not a massive amount though). It was then really lumpy and the turbo was spooling up quickly as normal but just loud and not making any boost.

 

I don't think its anything like head gasket (white smoke etc) as its driving. I pulled over and had a look for obvious signs but at idle the engine is perfectly normal, it's just under boost its bad. If it was head gasket it wouldn't run as the bores would be full of water etc. I managed to crawl it to work at about 30mph trying not to go in to boost (hard on a tdi that boosts at about 1.5k!), it was very slow and the turbo kept wanting to spool up but when did went lumpy.

 

I'm thinking the turbo has blown and oil is getting in to it and burning up in the exhaust (it's not blue so not getting in to the bores).

 

Anyone had this happen or has any other ideas? Also signs to check? I am going to take the pipes off the turbo if I can at lunch and see if I can see any obvious signs like excessive movement in the impeller shaft etc.

 

Cheers in advance!

Rob.

[johnnyfication 0]

Hi guys,

Anyway it's been running fine. I have been driving it past 2 days and noticed that when it got up the revs it lost power and backed off and then it would come back in again. I thought it was the ECU problem, it needs to be reset so must be a limiter or something kicking in.

 

This sounds like the MAF playing up, I had the same on my dads bora, changed that and was fine, however.....

 

Today however on the way to work it was running normally, I turned off down a country road and opened it up a bit (not thrashed it at all) but it was hardly going anywhere. All of a sudden there was a pop, the turbo went really loud and there was white smoke coming out of the exhaust (not a massive amount though). It was then really lumpy and the turbo was spooling up quickly as normal but just loud and not making any boost.

Rob.

 

I'm not sure about this, would be best to get it scanned with vagcom to see if there are any fault codes (the MAF unless really dead will not give a fault code), at least this would give some idea as to whats wrong.

 

HTH

Jonathan

[Toad 0]

If it is the turbo letting go, don't drive it. They can ingest and then run on thier own oil, only way you can stop them is to stall them. Have you got any leaks in the inlet or exhaust pipework?

[herisites 0]

Yeah I just had a poke around. Checked the turbo impellers to see if there's any movement in the shaft or whether they are fooked but that's fine and it spins fine. I then however noticed what the pop was and the white smoke, the intercooler pipe had burst off and the inlet pipe is pretty oily. So it's pressurising somewhere and has caused the pipe to pop off.

 

I heard of the turbo running on its own oil and the only way to stop it is to stall it. It's running perfectly fine on idle and i tested it round the car park when i connected the intercooler pipe back up (only had access to a cable tie to hold it on which obviously blew off again) and it drove as normal, but then blew it again when the turbo came on boost (full boost at least as was fine up to about 2.5-3k rpm).

[nemesis360 0]

The turbo is a variable vane unit, Id be 99% sure the vane is stuck and the turbo is over boosting.

 

The momentary loss of power is the ecu cutting into limp mode to protect the engine .

 

As its over boosting Id say one of the boost pipes has popped off causing the smoke and loud noise.

 

Really common problem, I probably fix 2 a month on average.

 

No need for a new turbo, take it off send it to me and Ill sort it out for you if you want.

[herisites 0]

That all sounds pretty spot on to me Graham! Thanks for the help. I'm going to get it home tonight by just whacking a new strong jubilee clip on the intercooler pipe and see what happens.

 

Are there any obvious signs that the vane has stuck, would I need to take it apart?

[nemesis360 0]

You wont tell 100% externally, you can check if the wastegate actuator arm is moving up and down easily (this controls the vane) but it can feel fine and still be sticking internally.

[herisites 0]

I have read about a suck test you can do with it, suck it to lift the flap and then listen for it to close quickly. Have you done that? What would I need to suck (ooerr!!)? :lol:

 

After doing bit of reading on it it seems that the vanes get sooted up quite and bit and so tend to clog up. A strip down, clean and lube up usually does the trick. There's probs more to it though.

 

So I would need to take the whole turbo off and send to you? That's not going to be fun!

[nemesis360 0]

Its easy to take the turbo off its right on top of the engine in the middle of the V...30 mins max to take off...though I have had some practice :lol:

[herisites 0]

Yeah it's easily accessible, but didn't know whether it would be a case of looks simple enough but ends up being a right ball ache like a lot of jobs on the corrados :lol: