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I’m suffering from the occasional overboost and dreaded "Limp Mode". The problem is well documented here for MKIV and earlier TDI's and I am very grateful to all of those who have painstakingly put all of this together. I’m assuming that things are pretty much the same for my BKD engine ( I thinks that’s what it is) I’ve worked through a lot of it and come to the conclusion that it is most likely an actuator problem or sticking vanes.

I have a VCDS and scoped the Turbo boost while the car was being driven on the open road. The resulting scope chart is attached and from my untrained eye it looks like the turbo (yellow line) is a long way off what the engine management system is asking for (green line).

The car is fitted with a Garrett 724930-6. (I have been able to read the model # on the turbo fitted in the car so I know this is correct) From what I understand this is classed and a “non serviceable†turbo. The local Garrett agent tells me that the only option is to buy a new turbo . I have also learned that it is not that the turbo can’t be dismantled just that Garrett do not supply any parts for it, I can’t even buy a new actuator for it apparently! So I have 2 questions:
  1. 1
Can I remove the turbo, dismantle it , clean it (following the procedure shown on the site for a MKIV) and put it back together again without needing and new parts to do this?
  1. 2
If 1 is possible am I wasting my time in any case and will the problem return fairly soon after?

For the record the car has done 140K kms ( 88K miles) and does most of its running on open roads, very little town driving. It is fitted with a DSG gearbox which, when in “D†changes up very quickly because of the high torque this engine produces. I can only assume that this has meant that the turbo has sooted up as it rarely gets a good blow out. I have tried the “Italian tune†but with limited success, the car tends to be ok for a day or two but will eventually over boost again.

Any help would be greatly appreciated, If I have to spend $2K on a new turbo them so be it but if a strip down and clean is possible and I’m good for another 80K miles then even better.
 

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From the pics I can find using google it looks like it comes apart ok, it's just the exhaust end and you just need to be able to pop the outer cover off so you can get to the vanes, a lot of the time it's just you can't buy the spares for servicing them like bearings, seals etc but they still come apart ok. You might be worth trying some of that innotec stuff. I've never used it myself but other people seem to rate it ok. Google "innotec turbo cleaner" and see what you think, you could also ask for opinions on it on the forum.:)
 

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Something is strange there.....the green line is perfectly flat in some areas. Unless you're holding the engine at an exact power load I don't think this is normal.

What I see is heavy power requested and the turbo lagging. It normally doesn't stay flat like that though because the boost requested should change. The fact that the heavy revving fixes it for a day suggests that it's not a vac line or wiring problem.

I don't see why you couldn't take your turbo apart. If you do, feel free to take lots of pictures and share what you learn! The turbo ring should look a little different than the ALH engine writeup.
 

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Thanks, I'll see what I can find about innotec. One small challenge I have is that the Garrett agent doesn't carry this turbo in stock in my part of the world (New Zealand), the VW agent does, but at twice the price. If I get the turbo apart and find other issues I'll be off the road for a while while I wait for it to arrive.
 

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Something is strange there.....the green line is perfectly flat in some areas. Unless you're holding the engine at an exact power load I don't think this is normal.

What I see is heavy power requested and the turbo lagging. It normally doesn't stay flat like that though because the boost requested should change. The fact that the heavy revving fixes it for a day suggests that it's not a vac line or wiring problem.

I don't see why you couldn't take your turbo apart. If you do, feel free to take lots of pictures and share what you learn! The turbo ring should look a little different than the ALH engine writeup.
Thanks, We were travelling down hill on a trailling throttle for some of the time perhaps that might explain some of it, still it does look odd. FYI the battery in the car was getting pretty tired and actually failed to start the car the other day. I have since replaced it but I would think that lower power battery wouldn't have too much influence on a running motor. Having said that I did have a Passat W8 a while back with a tired battery. The car ran a whole lot better after I fitted a new one
 

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If you need it pm me and I'll give you the email address of a guy called Ryan also known as ryanp on the tdiclub forum. He ships turbos to the states from the UK that arrive almost the next day and he's pretty knowledgeable on what turbos fit what, he also usually has second hand ones too so he'd be worth a try if you get stuck but I think you'll find your turbo will be fine with a clean.:)
 

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Just an Update... Did some more searching and found some basic instruction on a SEAT forum for removal of the turbo on a 2.0 BKD engine. It seems to be a bit simplier but it still took me a while to remove it. Opening up the turbo and all is revealed... Soot build up in a several places and what appears to be loose particles of soot( though they may have broken away when I pulled it apart) floating round in there. I'm hoping therefore a good clean up will do the trick. I've taken lots of photos and will write it up once I've finished
 

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Well the jobs done, removed the turbo, pulled it apart. Little sign of wear but lots of soot and grimey build up. Cleanned it all, even have the manifold acid dipped to remove any buildup in there that may come loose and foul things up again.. I've rescoped in with VCDS and it looks to my untrained eye to be a lot better. I'll try and add it as a second thumbnail I've taken lots of photos and will do a write up on how to remove the turbo from a BKD engine.
 

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From the pics I can find using google it looks like it comes apart ok, it's just the exhaust end and you just need to be able to pop the outer cover off so you can get to the vanes, a lot of the time it's just you can't buy the spares for servicing them like bearings, seals etc but they still come apart ok. You might be worth trying some of that innotec stuff. I've never used it myself but other people seem to rate it ok. Google "innotec turbo cleaner" and see what you think, you could also ask for opinions on it on the forum.:)
Thanks for this, Check my latest postings, looking good so far but I guess time will tell!
 

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Well the jobs done, removed the turbo, pulled it apart. Little sign of wear but lots of soot and grimey build up. Cleanned it all, even have the manifold acid dipped to remove any buildup in there that may come loose and foul things up again.. I've rescoped in with VCDS and it looks to my untrained eye to be a lot better. I'll try and add it as a second thumbnail I've taken lots of photos and will do a write up on how to remove the turbo from a BKD engine.
Many thanks! And yes, the new graph looks much better.
 

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Discussion Starter #12
One thing I have also had is a minor coolant loss. I've had the car 18 months and the coolant level drops from max to min over about 2000kms. The agent did a full preassure test and cylinder leakage test at the major service (120k kms) but could not find anything. The car runs fine, apart from this over boost issue, has no starting or overheating probelms so its all just seemed odd.

I think I have found the problem though and I suspect its a porous head. Water is leaking into the #2 exhaust port, I found it by chance when I had the turbo off as the car was up on ramps for about a week and there was a small, about 5ml, of water on the workshop floor. I could actually see and feel the water in the exhaust port so there is no doubt about where it was coming from. It would also explain why no amount of testing would find it, any water leaks into the exhaust and quickly turns into steam. So my thinking is that there are cracks in the head between the water jacket and the exhaust port. They must be pretty small given the slowness of the leak. Given that this must be in a low preassure area it's been suggested that I try a adding some coolant sealer like K Seal and see if that stops it. Given the only other option seems to be a head replacment the idea obviuosly appeals. I'm keen to know if anyone else has has this issue and had any success with additives. Likewise Im keen to know if there are any additives that are better than others or whether to avoid them at all costs?
 
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