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Author Topic: No boost! K04 Turbo failure. All sorted!  (Read 6958 times)

Offline samb377

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No boost! K04 Turbo failure. All sorted!
« on: October 05, 2014, 10:05:05 pm »
Went to accelerate, turbo kicked in, there was a 'hoot' noise and then nothing... No boost.

No light on dash, no codes on VCDS, had a good hunt for a popped hose but nothing. At idle it seems a bit juddery.

I'm no expert with VCDS, but I did take a look at the measuring block that shows requested and actual boost. At idle the requested seemed to say ~300mbar (it fluctuates) and the actual was just a steady 1000mBar, i.e. atmospheric, i.e. no boost. I went for a drive and also looked at the n75 duty cycle, which stayed at 0 (I have no idea what this means, apart from that it's not doing what it's supposed to do)

And before anyone says it, it's not the DV! Changed it two weeks ago and checked it today. It's also not likely to be anything to do with the cam follower, since this was changed 6months ago.

Has my turbo had it?! Maybe I'll need one of those K04s that Alex has for sale!
« Last Edit: October 13, 2014, 10:04:27 pm by samb377 »
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Offline GrayMK5GTI

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Re: No boost!
« Reply #1 on: October 06, 2014, 07:40:54 am »
Could be the N75? Or maybe the turbo failing (hope it's not this)

Good luck in finding the fault
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Offline samb377

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Re: No boost!
« Reply #2 on: October 06, 2014, 10:32:51 am »
N75 makes sense.

If it fails, it should fail safe, i.e. wastegate open (0%), so as boost builds it just vents. The wastegate is on a spring, so although it’s closed mechanically the pressure opens it when it buids. The N75 is like an off/on solenoid that regulates how much the wastegate can open (when boosting it’s cycling at quite a rate I think), hence controlling the boost. Maybe it’s this? Maybe the noise is a lot of air passing through a fully open wastegate, which doesn’t usually happen?

If I give it he beans, the car doesnt move much, but it does make the hoot noise.

Anyway, this is one plausible explanation... I think I'll leave it to the professionals.
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Offline mvb12

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Re: No boost!
« Reply #3 on: October 06, 2014, 12:51:44 pm »
you sure its not a boost leak so a pipes off, what IC you got?
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Offline GrayMK5GTI

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Re: No boost!
« Reply #4 on: October 06, 2014, 01:08:50 pm »
The more I think about it, the more I think its probably the N75. The 0% Duty gives it away
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Offline mvb12

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Re: No boost!
« Reply #5 on: October 06, 2014, 01:14:55 pm »
I just saw no boost and didn't even read his last  :ashamed:
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Offline samb377

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Re: No boost!
« Reply #6 on: October 06, 2014, 02:01:14 pm »
This is all making me feel more positive about the situation, so finger's crossed it will be the N75. I'll do some more logging tonight, and it's booked in at the local specialist tommorow, so I'll hand over all the info to him.

Cheers for the pointers!
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Offline samb377

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Re: No boost!
« Reply #7 on: October 06, 2014, 02:05:42 pm »
I have checked all the pipes and everything looks secure and in good condition. I'm guessing even if I did have a hose off the N75 would cycle, unless it's an indirect measurement (I dont think it is).
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Offline samb377

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Re: No boost!
« Reply #8 on: October 06, 2014, 08:51:10 pm »
Ok so I've had a bit more time to actually look at the log (below). N75 seems to operate occasionally but most of the time seems to be at 0%. It's also clear that I can't get it over 4000rpm.

Over to the garage!

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Offline samb377

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Re: No boost!
« Reply #9 on: October 09, 2014, 09:55:13 pm »
This isn't getting anywhere quickly it seems. Nick at R-Tech has been really helpful at providing some pointers, but so far the local independent haven't been able to identify the underlying cause, and seem to think it's actually the turbo that's gone. They managed to get an endoscope in there and identified that the turbo isn't rotating, or at least it does a bit (slowly) but then stops, making the 'hoot' noise as it stops.

So what do I know...
  • Zero boost and not intermittently.
  • Turbo not starting on car start up (or rather it begins to spin and then stops).
  • Wastegate is not opening when car is running, but will when forced by applying pressure, so the mechanics of the actuator seem to work.
  • N75 is reading 0% most of the time (as above), but I think the ecu would only activate the N75 once boost is achieved (?).
  • As per Nick's instructions, the garage have checked MAF, cam follower, air filter, hoses. Nick also suggested N75, fuel pump, catalytic convertor and I think the garage have checked these...I'll check tomorrow. Note that Nick made these suggestions before I knew the turbo was not spinning!
  • There are no VCDS codes.

I'm a bit concerned that the car is in limp mode and telling the turbo not to rotate. I'm not sure how to test this, and it seems really odd that the car is throwing any codes. Perhaps it is just a mechanical k04 failure, but I haven't heard many examples of this.

I'm going to visit the garage tomorrow, to go through it with them, so hopefully I'll have some answers then!
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Offline samb377

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Re: No boost!
« Reply #10 on: October 10, 2014, 11:57:47 am »
Well it turns out the turbo has blown. Cracked in half to be precise.

The first photo shows where the turbo housing cracked, where the two parts join. The soot marks are clear, so it has been cracked and blowing for a while, before catastrophic failure. The two parts are now not in alignment, and therefore (as you can see in the second photo) the shaft and housing are not aligned and the impeller is rubbing against the housing.

The impeller rubbing against the housing is what's making the 'hoot' noise (it didn't sound metallic when driving).

Next step is trying to get the warranty company (WMS Group / VGS) to pay up. So far they have asked for the turbo for inspection. I want to get driving so I've said that I will buy at risk, if they tell me how much they will pay. They aren't being very forthcoming with this figure, but apparently they only give reconditioned turbos (if these exist for k04), or pay the equivalent towards the claim.

This warranty company have clearly got teflon shoulders, and have already wound up the garage owner trying to convince him that it's 'probably wear and tear due to carbon build up, which is common with VW turbos'. It's a petrol engine you morons!

A new K04 from Borg Warner is about £1000. The second hand K04s from Alex are £400, so these are the options at the moment. I don't like the sound of a reconditioned one.


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Offline Scottymon

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Re: No boost!
« Reply #11 on: October 10, 2014, 12:04:40 pm »
Yes mate, don't have the mechanic agree to that sh*t about wear and tear, as they will instantly refuse the claim.

Had that on my old Saab, luckily I knew the garage owner quite well and he knew what they were trying to do, that was AA warranty.

Also, I would honestly wait until they agree a price and method of buying, otherwise they could refuse later because the wind is blowing in the wrong direction.
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Offline samb377

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Re: No boost!
« Reply #12 on: October 13, 2014, 10:03:26 pm »
All sorted! Warranty company agreed to pay out (no arguments at all!) for the turbo and 4.2hrs labour, and the new turbo is arriving tomorrow from Alex (AKS Tuning). Nearly back on the road!
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