A4 2.5 TDI - Turbo

[herisites]

Hi guys,

New to the forum and just want to pick a few brains really.

I am currently using my old man's audi (2.5 v6 tdi) as my corrado is in the body shop after a shunt.

Quick story of the audi , it had been off the road for ages, we tried starting it but it didn't want to know. We gave it to a 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 plugs 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) 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.

[herisites]

I went and had a look at it quickly in my lunch break. The turbo was fine from what I could see on the impeller side, it spins fine and there's no movement in the shaft.

I then noticed the pop was due to the intercooler pipe blowing off! But the inlet contains oil so any ideas on that? An oil seal perhaps and something's causing the inlet to pressurise and blow the pipe off the intercooler?

Cheers.

[zollaf]

you will normally have some oil in the manifold. nothing to worry about, as long as its not loads of oil. its just the breather system.

[herisites]

Yeah that's true, it's just the intercooler pipe then, either the garage that fixed before problems have had to remove it and not put it back on properly or it's just old or there's pressure building up. I can't see there really being pressure build up in the inlet though, the turbo span fine so I think it's probs just from age, it's on 80k.

[herisites]

After a bit of research I believe the problem to be the EGR valve stuck open causing the turbo to overboost which blew the pipe off. The loss of power before was it going in to limp mode so it obviously saw it coming!