TDI Turbo Failure - spend $2000+ or find another solution.

[moreboost]

A mate just bought an 07 TDI Sportline Golf, 65,000kms, manual. He likes my GTI but was chasing fuel economy as a weekend in the city is a 1000km round trip.

When the owner was questioned re the condition of the vehicle he informed us that his VW specialist had indicated the turbo would need replacing in the next 6 to 12 months and then said that he would reduce the price by $2K.
During our test drive the turbo was noisy but not in a normal way. Given the price and the fact that we had driven over 450kms that morning to inspect it we decided to purchase and head home.

Given the car had been regularly serviced and that the overall condition was near perfect it had to be worth the asking price, plus at those Kms was the Turbo really about to fail??

About 100kms into the trip home we suddenly had no boost, a car that was cruising so well was now a bit too sluggish to pass road-trains easily. Mmmm... turned the ignition off and back on, boost back and on our way again. All was well for another 200kms, slowed after passing a few cars and no boost again but this time we had an "emissions garage" warning as well....short of a very expensive tilt tray trip home it was a case of slow up and cruise home. Ignition on and off once again gave us boost but the warning stayed.

Back home and scour the forums for similar problems.....could be a number of things but I kept on thinking - a turbo failure at 65000 kms??? Why the strange wail from the turbo?? It didn't sound like the whistle associated with an imbalance caused by damaged turbine blades. OK if the local forums didn't provide any obvious solutions just Google it....

Typed in 'turbo siren sound TDI' and there seemed to be an answer.....seized vanes....VNT turbo....and the solution???

Mr Muscle yes oven cleaner the NaOH variety......

So we set about removing the dump pipe to have a look, turbo vanes perfect, no axial or radial play in the shaft (as expected). So Mr Muscle it was.....45 mins of soaking, a big rev and miraculously....warning cleared itself, siren gone and drives like a bought one...HAPPY DAYS!!!!

Driven considerable distance since under various load conditions and performing perfectly.

We made a replacement dump pipe so the muck didn't pass through the cat, total cost including Mr Muscle $23, and NO we didn't contact the previous owner to gloat......

[lhennessy]

Nicely done haha, if it does come back pull apart and clean the EGR. One of the possibilitys of emission garage, is the flap being stuck or malfunctioning which can be caused by soot build up in the EGR.

Even if it dosnt it would be good to clean it out anyway.

[moreboost]

Yeah, EGR clean next on the list.
Reason why we went searching for other alternatives for the Emissions Garage was that when pressed the seller said " a boost warning light" had come on previously, and when we had issues on trip home he said " yes that Emissions Garage fault was what happened and that was why I was told it needed a new turbo"

If anything, I think with seized vanes there was too much boost and the sudden lack thereof was the electronics protecting the engine.
We went to quite a bit of trouble to inject the cleaner into the turbo beyond the vanes and ensure that none of it found its way onto driveshafts etc.

Amazing how long we could run the engine through 2 inch PVC pipe with alfoil used to insulate the plastic dump pipes 90 degree bend.
Sounded pretty purposeful .....

[brad]

Most (not all) oven cleaners will eat into aluminium if the active ingredient is Sodium hydroxide (Lye / caustic soda). So you need to be a bit careful what happens down the line from the turbo. It's probably a good idea to do a water based carbon clean afterwards to dilute the oven cleaner or find an oven cleaner that doesn't affect aluminium.

Alternatives to Oven Cleaner are full strength Simple Green, methanol based (not caustic) carby cleaner / paint stripper (Methyl Chloride). Keep all these things away from any electric motors as they will eat away the carbon brushes.

here's what I mean by a water based carbon clean but I'd use a sprayer / mister rather than rely on steady hands. You can put metho or white spirit in the water mix as well.

[Jarred]

I dare say that this is what happens when you don't properly.. flog.. a new TDI regularily. it's amazing how quickly they can get gummed up with crap.

[benough]

I concur on this. My GT TDI had a DPF clog in the first 1000km.

The service manager told me to flog it. Have done ever since. 185,000km later, no issues.

[Ryeman]

I concur on this. My GT TDI had a DPF clog in the first 1000km.

The service manager told me to flog it. Have done ever since. 185,000km later, no issues.

So what technique do you use and how often?

[h100vw]

So what technique do you use and how often?

Don't be frightened to rev it so that the variable vanes actually get moved about.

VNT turbo cleaning, disassembly, replacement, or how to repair stuck turbo vanes-mk4 | VW TDI forum, Audi, Porsche, and Chevy Cruze diesel forum

Then they don't seize up.

[benough]

Everyday. Just when there's space and it's practical, I give it a boot full.

Not constantly of course, but you gotta have the throttle pinned at least once a day.

Make sure you do it when it's at operating temperature. Oil temp doesn't get to 90 till about 15mins on these.

[gldgti]

OK, looks like we have snowballed here.

Seized vanes will cause boost problems, not just a weird noise. You need to get it scanned by a VAG specialist or someone who can log with VCDS, check for fault codes especially to do with boost pressure out of range and that sort of thing.

Then I would go for a drive and log boost in a 3rd gear pull. Log boost actual and boost spec. and graph them in excel (look in my 1.9tdi powerquest thread for an example) and post it here. This will give you a good idea of how the turbo is performing - if the pec and actual vary wildy from eachother, it will be easy to tell from the plot what is going on.

It is NOT POSSIBLE to diagnose seized vanes on sound alone.

Now - if the turbo has a bit of its turbine wheel broken off (I have seen this on TDI turbo's before) there are a few places (especially in the UK) that sell CHRA (core housing rotating assembly) rebuild kits for TDI turbo's, and your looking at around $500 for an assembly landed in aus. All that is required to rebuild is to disasseble the CHRA from the old turbo's exhaust housing and compressor housing, check the vanes and clean if necessary, and then reassembly with the new CHRA. they come balanced and everything, so you essentially end up with a brand new turbo.

hope to help

[moreboost]

So......lets keep this in perspective.

We had a weird sounding turbo, yes a siren sounded the best description.... the previous owner admitted that there had been boost related warnings diagnosed by a VW specialist......

Any number of posts on our web search confirmed that a 'weird siren noise' often equated to seized vanes.....

The hot side of the turbo doesn't contain any aluminium.....

We ran a PVC dump and exhaust until there was NO further residue exiting the turbo...

I think the job was done without any damage to the car and it is running perfectly.....As I said in my second post we went to a lot of trouble to avoid doing damage. I wouldn't dream of using NaOH if the turbo wasn't significantly lower then the cylinder head ports. We timed the flow of foam into the turbo after working out flow rate and rough volume of turbo.

Thanks Gavin for the Link, we were about to head down that path before we came up with the Mr Muscle solution.

We gave our fix a try, if it didn't work we would have been pulling the turbo next and giving it a manual clean.
Will keep you posted if there are any further issues.

[gldgti]

Yeah good luck to ya - I'm just saying you can actually diagnose it with VCDS and a bit of testing rather than going on what some internet posts/youtube videos say.

You might have saved yourself the hassle of what you've already done.

My advice about rebuilding is only for if you need to end up doing it - not once did I say thats what was wrong with the car. I certianly wouldnt recommend pulling the turbo before you've done some proper diagnostics, unless you are just loving spending time under the car.

If someone can explain in engineering terms how siezed vanes will cause a siren sound, I'll give you $1000.

(The only thing remotely close might be severe turbo overspeed due to the vanes being closed and this would cause crazy boost.)

[moreboost]

Our problem is that there are no VW specialists in town and those in Perth are at least 425 kms away.
A VW 'dealer' opened here last year, same company as the Holden dealer and they do Jeep, Chrysler etc as well. Don't seem to keep service parts even......
So we went looking for a solution with the resources we had.

Post Mr Muscle the noise is different. Before the turbo seemed to spool up momentarily after you released the throttle and seemed slow to spin down,

something like this ( video is no load though)

https://www.youtube.com/watch?v=cc4ykrnn_3c

once the vanes were free (could physically feel the difference on the actuator) it was immediately obvious that the turbo slowed faster (vanes opening fully). Now sounds like any wastegated turbo....

[brad]

I thought those old fashioned air raid sirens were fixed vanes?

I'd assume all you need is the right angle & enough speed. Get on the right harmonic & it would howl like a coyote.

[benough]

That would be a hilarious trick, if you could position a VNT's vane to that point and make it howl on them. hahaha