What could be the cause of 3 failed turbos?

What could be the cause of 3 failed turbos?

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Discussion

Elatino1

Original Poster:

895 posts

20 months

Wednesday 30th September
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I have an impreza STi twin scroll with a roller bearing vf36 turbo.

When the previous owner bought the car it had to have a replacement turbo as it was becoming whiney and sounded like a police siren.

He drove the car with a knackered radiator and overheated it cooking the head gaskets. I bought the car had the head gaskets replaced heads skimmed etc and the whining started to become noticeable again. I sent the turbo off to be replaced and after 1k miles it has started becoming noisy again..grrrrr. The turbo has not lost any power and holds boost at 1.4bar no problem but is getting noisier and noisier.

The turbo refurbisher has suggested to check that it has the correct restrictor in the oil feed. I have had the turbo removed and will send it back to him along with the banjo bolt with the restrictor attached. The turbo is getting lots of oil so I am not confident this is the problem.

Anyone come across this before? Any ideas what might be the problem if the restrictor is correct? It is becoming an expensive issue and I dont want to just get it refurbed again and try my luck with no actual resolution.

Any suggestions or help appreciated. Thanks

enginebuilder

54 posts

58 months

Thursday 1st October
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If it is getting oil as you stated, making sure the little banjo bolt filter in the avc's oil feed supply to the turbo is clean & fitted the correct way round, the other common thing I find is the turbo when all bolted down is distorted, caused by ill fitted or distorted up pipe & support brackets, or the casing actually in contact with the gearbox / engine mating faces.

320d is all you need

593 posts

2 months

Thursday 1st October
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Is there any damage to the compressor wheel, or is it just the bearing assembly? I presume oil feed is replaced as well as full oil change on installation of new turbo?

Also, who is doing the turbo rebuilds, is it a quality shop using quality bearings or a cheap shop using cheap bearings?


chrisch77

297 posts

34 months

Thursday 1st October
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Disclaimer - I know nothing about a typical Subaru turbo setup!

But if you are confident that the oil supply is 'correct' then I would be wanting to check how the oil returns from the turbo. No good feeding oil in if it can't get out as this will not allow the heat to be dissipated.

Another question is what happens when you turn the engine off, is there any provision for an electric pump on the oil system to continue circulating oil to mitigate heat soak in the turbo? Do you let the engine idle for a while after a run or switch it off straight after a thrash?

Elatino1

Original Poster:

895 posts

20 months

Thursday 1st October
quotequote all
enginebuilder said:
If it is getting oil as you stated, making sure the little banjo bolt filter in the avc's oil feed supply to the turbo is clean & fitted the correct way round, the other common thing I find is the turbo when all bolted down is distorted, caused by ill fitted or distorted up pipe & support brackets, or the casing actually in contact with the gearbox / engine mating faces.
Will be getting the banjo checked when the turbo goes back for another rebuild. Thanks for the suggestions will look out for these.

Elatino1

Original Poster:

895 posts

20 months

Thursday 1st October
quotequote all
320d is all you need said:
Is there any damage to the compressor wheel, or is it just the bearing assembly? I presume oil feed is replaced as well as full oil change on installation of new turbo?

Also, who is doing the turbo rebuilds, is it a quality shop using quality bearings or a cheap shop using cheap bearings?
Fastline turbos is doing the rebuilds. I haven't found anyone else that rebuilds these turbos. At £750 I don't think it was a particularly cheap repair. Was silent when i got it back.

Elatino1

Original Poster:

895 posts

20 months

Thursday 1st October
quotequote all
chrisch77 said:
Disclaimer - I know nothing about a typical Subaru turbo setup!

But if you are confident that the oil supply is 'correct' then I would be wanting to check how the oil returns from the turbo. No good feeding oil in if it can't get out as this will not allow the heat to be dissipated.

Another question is what happens when you turn the engine off, is there any provision for an electric pump on the oil system to continue circulating oil to mitigate heat soak in the turbo? Do you let the engine idle for a while after a run or switch it off straight after a thrash?
No turbo timer but I always leave it idling for a minute or 2 at least after a decent drive.

Will also be checking the return. Thanks

TEKNOPUG

14,715 posts

164 months

Thursday 1st October
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Idling is no good as there is no airflow through the car. You are actually increasing the heat soak. You need to back off the boost and drive gently for the last few miles of your journey.

However, I doubt that this is the reason your turbo is failing. It will be an oil supply/flow issue providing everything had been rebuit and fitted correctly.

320d is all you need

593 posts

2 months

Thursday 1st October
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I've owned 4 turbo charged cars and never had a turbo fail.

While I don't rag it to my parking spot and switch it off, I don't sit there for 5 minutes idling after driving either. Never had an issue so far.

Elatino1

Original Poster:

895 posts

20 months

Thursday 1st October
quotequote all
320d is all you need said:
I've owned 4 turbo charged cars and never had a turbo fail.

While I don't rag it to my parking spot and switch it off, I don't sit there for 5 minutes idling after driving either. Never had an issue so far.
Good for you. I also own 2 other turbo cars and have had 15 others previously. This is the only one I have had any issue with a turbo.

Nobody mentioned sitting idling for 5 mins.

Elatino1

Original Poster:

895 posts

20 months

Thursday 1st October
quotequote all
TEKNOPUG said:
Idling is no good as there is no airflow through the car. You are actually increasing the heat soak. You need to back off the boost and drive gently for the last few miles of your journey.

However, I doubt that this is the reason your turbo is failing. It will be an oil supply/flow issue providing everything had been rebuit and fitted correctly.
Of course idling is good practice, it keeps oil circulating and stops the turbo drying out at high temps. It is why there is a a sticker on the door saying "after highway driving leave to idle for 2minutes" on Subarus.

Of course a slow cool down whilst moving is ideal but not always possible, such as traffic or track days

Elatino1

Original Poster:

895 posts

20 months

Thursday 1st October
quotequote all

320d is all you need

593 posts

2 months

Thursday 1st October
quotequote all
Elatino1 said:
320d is all you need said:
I've owned 4 turbo charged cars and never had a turbo fail.

While I don't rag it to my parking spot and switch it off, I don't sit there for 5 minutes idling after driving either. Never had an issue so far.
Good for you. I also own 2 other turbo cars and have had 15 others previously. This is the only one I have had any issue with a turbo.

Nobody mentioned sitting idling for 5 mins.
Oh, Okay. Sorry. I was just trying to be helpful. I have quite a lot of knowledge of turbochargers, given my engineering background. My comment was some artistic merit on the idea that using "turbo timers" or sitting there for 2 minutes does some good (Look at emergency services vehicles, they are driven hard, from cold, and never allowed to "cool" - most are very reliable).

With an attitude like that, I will leave it.



Edited by 320d is all you need on Thursday 1st October 19:38

ReverendCounter

4,121 posts

135 months

Thursday 1st October
quotequote all
320d is all you need said:
With an attitude like that, I will leave it.
320, looking at this conversation from the outside, so to speak, it does come across from your opening line that you're suggesting the OP doesn't know how to look after his car/s.

Just saying.

320d is all you need

593 posts

2 months

Thursday 1st October
quotequote all
ReverendCounter said:
320d is all you need said:
With an attitude like that, I will leave it.
320, looking at this conversation from the outside, so to speak, it does come across from your opening line that you're suggesting the OP doesn't know how to look after his car/s.

Just saying.
Ok, well apologies if that's the case - not how it is intended.

Elatino1

Original Poster:

895 posts

20 months

Thursday 1st October
quotequote all
thumbup
That is how I read it. I am not new to turbocharged cars, I am new to turbo problems. All of my cars are well over serviced and treated with ocd type of care.

texaxile

2,416 posts

109 months

Saturday 3rd October
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Might be worth posting this in the "Home mechanics" sub forum, there are some really knowledgeable guys there who might be able to give you a pointer as well.
I can only speculate, but premature Turbo failure is often down to an oil issue of some description, often too little or otherwise poor manufacturing / rebuild, even something as small as a slight kink or blockage in the feed could cause problems that get compounded over time.


Elatino1

Original Poster:

895 posts

20 months

Saturday 3rd October
quotequote all
Have picked the turbo now. The feed is a metal pipe with no kink or blockage as is the return which goes straight to the sump. The shaft is rock solid and the wheel looks brand new, it is just the bearings that have become noisy again.

ReverendCounter

4,121 posts

135 months

Sunday 4th October
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Is there any way you can fit a new bearing only and see if it starts to whine pretty quickly again?

MDMA .

5,844 posts

60 months

Sunday 4th October
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Have the 3 failed turbos all be "re-built" at the same place? This could be the problem.