Why does a Turbo fail?

[Craigie]

Son’s 2015 Polo 1.8 GTI turbo has “seized” according to my local indie. Son took it to him when he felt the power disappear. Car has only done 30000 miles.

Prices for replacements are scary but not only that, I am concerned that whatever happened to this Turbo could happen again? Indie says he has checked and everything else seems fine and it must just be a fault with the Turbo but that doesn’t fill me with confidence.

Do they just seize??

[r44flyer]

I guess it could seize, if it was run without oil.

When you say 'indie' do you mean a VW specialist or just a local garage?

We need more symptoms and whatever fault codes it has.

[RazerSauber]

Could be one of several reasons. I find that seizure is usually due to insufficient oil flow. Turbo gets too hot, no lubrication and cooling from the oil and bam, seized solid. Could also be fuel getting into the oil, reducing lubricity but this tends to be more prevalent on diesels where the engine is prevented from completing a DPF regen. If I were you and the vehicle is in the garage, definitely worth checking the oil passageways aren't blocked or restricted so proper oil flow is supplied to the turbo.

[Craigie]

r44flyer said:

I guess it could seize, if it was run without oil.

When you say 'indie' do you mean a VW specialist or just a local garage?

We need more symptoms and whatever fault codes it has.

It was in my local indie garage. Back now on the driveway waiting our next move. I’ll speak to him tomorrow to see if he got fault codes. According to my son he was told that “ he accessed the turbo and stuck finger in which is supposed to be able to turn it but it was seized solid”

[GT9]

Quite often it can be due to overheating the residual oil left in the turbo at shutdown. If the engine is often stopped suddenly after 'spirited' driving, the turbo hasn't had a chance to cool down. Leaving the engine running for a few minutes or a period of 'cool down' driving at the end would maybe avoid this.

[Wombat3]

How often has the thing had its oil changed? If its on some silly long life service schedule then that really doesn't help. Once a year or absolute Max 10K miles for anything with a Turbo IMO, & more often if its any sort of performance motor.

Also, as above, shutting it off when its very hot never helps, best to let it cool down at idle for a minute or so.

[stevemcs]

Lack of oil, poor quality oil, wrong oil, lack of oil changes - the 1.8 has issues with sump blocking and when it struggles to pump oil around the engine the part furthest away dies, usually the turbo. If they cannot turn the impeller by hand then its new turbo time, possibly drop the sump and clean the pick up pipe, replace feed and return pipes and fresh oil and filter.

We did a biturbo on a transporter a few weeks ago, that was stupidly expensive as it was engine and gearbox out to change.

[georgeyboy12345]

Take the car to another garage to get a second opinion. I have had a garage try to have my eyes out with this kind of thing before. It might just be a hole in the turbo or intercooler pipe, or a faulty actuator, etc. Nothing to lose and potentially £700+ to be saved.

[stevemcs]

georgeyboy12345 said:

Take the car to another garage to get a second opinion. I have had a garage try to have my eyes out with this kind of thing before. It might just be a hole in the turbo or intercooler pipe, or a faulty actuator, etc. Nothing to lose and potentially £700+ to be saved.

Or the turbo fails on the way to the second opinion spits the bits through the engine and then more bits are needed. If it was a hose split you would hear it.

[liner33]

There is no need to idle an engine to allow the turbo to cool down , not on a modern car , a series 1 RS Turbo perhaps but nothing in the last 20 years . Dont switch the engine off at max rpm and load but after normal driving it's not going to cause an issue

Most turbo failures are oil related in some ways but of course manufacturing defects exist as well , plus running a car with a remap or even an air leak will work the turbo harder and can cause failures

[cerb4.5lee]

liner33 said:

There is no need to idle an engine to allow the turbo to cool down , not on a modern car , a series 1 RS Turbo perhaps but nothing in the last 20 years .

I'd got that used to letting the turbo cool down on my S14a 200SX, that I still do it on my F82 M4! I know that I don't have to, but it makes me feel better still doing it though.

I won't rag a car either...until the oil has got up to around 80 degrees as well. I probably baby modern cars too much to be fair.

[Smint]

S'funny, we keep being told the latest everything engine wise is so much better than everything that came before and needs no care or common sense mechanical sympathy.

Yet people who care for and service their cars well, often giving the maker's advice (who warrants it for 3 years only) a good ignoring re long life engine servicing, and allow their engines to warm up and cool down sensibly, manage to go through the years without a single engine or turbo failure to their name over sometimes millions of miles driving.

You see the same with automatic gearboxes, never needs the oil changing guv its 'sealed for life', a phrase which means what exactly? so long as it lasts till the warranty expires when it's no longer anything to do with the maker, owners with more nous ignore that sealed for life cobblers and get their gearboxes serviced at sensible intervals, which invariably means the box never fails.

Usually when a turbo fails there's lack of mechanical sympathy (abuse) or stupid service intervals or a lack of oil in the sump among the reasons, the problem with replacement depends to a certain extent on why it failed, could there be carboned oil residue partly blocking the oil galleries (common issue with the 1.6 PSA Diesel of Doom) which if left in place would not be good news for the replacement turbo.

[Evoluzione]

If your mechanic is honest then it needs to go to a turbo specialist for a PM, if they're any good they'll tell you.

[NMNeil]

Craigie said:

Son’s 2015 Polo 1.8 GTI turbo has “seized” according to my local indie. Son took it to him when he felt the power disappear. Car has only done 30000 miles.

Prices for replacements are scary but not only that, I am concerned that whatever happened to this Turbo could happen again? Indie says he has checked and everything else seems fine and it must just be a fault with the Turbo but that doesn’t fill me with confidence.

Do they just seize??

Take your pick from the possible causes.
https://www.cummins.com/sites/default/files/2019-0...

[Boosted LS1]

OP, does the shaft turn, if not it's seized. As for why, who knows but that could be an oiling issue. If you want the garage to establish the cause and carry the liability for that it'll be expensive.

I'd ask them to clean the oil supply line and replace the turbo.

[Wombat3]

Smint said:

S'funny, we keep being told the latest everything engine wise is so much better than everything that came before and needs no care or common sense mechanical sympathy.

Yet people who care for and service their cars well, often giving the maker's advice (who warrants it for 3 years only) a good ignoring re long life engine servicing, and allow their engines to warm up and cool down sensibly, manage to go through the years without a single engine or turbo failure to their name over sometimes millions of miles driving.

You see the same with automatic gearboxes, never needs the oil changing guv its 'sealed for life', a phrase which means what exactly? so long as it lasts till the warranty expires when it's no longer anything to do with the maker, owners with more nous ignore that sealed for life cobblers and get their gearboxes serviced at sensible intervals, which invariably means the box never fails.

Usually when a turbo fails there's lack of mechanical sympathy (abuse) or stupid service intervals or a lack of oil in the sump among the reasons, the problem with replacement depends to a certain extent on why it failed, could there be carboned oil residue partly blocking the oil galleries (common issue with the 1.6 PSA Diesel of Doom) which if left in place would not be good news for the replacement turbo.

Spot on. Same applies to "sealed for life" manual gearboxes IMO changing the oil in them at 60K is cheap insurance.

Some good suggestions also being made re residues blocking oil supply. The first VAG 1.8 turbos that they put in Passats & Audi A4s were notorious for "turbo turds" blocking the screen covering the oil pickup in the sump thus restricting oil flow to the whole engine. Part of the problem was that the silly thing had barely 4 litres of oil in it in the first place.

So you have a high revving 1800cc engine doing 150+ hp with a 10k mile oil change on only 3 & a bit litres of oil....it's not going to end well eventually.

[Craigie]

Thanks for all your replies. I will speak to the indie today and try and get some more information.
What are the panels thoughts on second hand turbos ie from eBay/breakers yards? Worth the gamble?
I am being quoted around £1200 for a refurbished, year guaranteed OEM from a local Turbo specialist but there also seems to be some scrap type turbos from EBay for only a few hundred?

[Smint]

Wombat3 said:

Spot on. Same applies to "sealed for life" manual gearboxes IMO changing the oil in them at 60K is cheap insurance.

Some good suggestions also being made re residues blocking oil supply. The first VAG 1.8 turbos that they put in Passats & Audi A4s were notorious for "turbo turds" blocking the screen covering the oil pickup in the sump thus restricting oil flow to the whole engine. Part of the problem was that the silly thing had barely 4 litres of oil in it in the first place.

So you have a high revving 1800cc engine doing 150+ hp with a 10k mile oil change on only 3 & a bit litres of oil....it's not going to end well eventually.

Indeed, another issue with modern engines (particularly Diesels with really high compression pressures) is that now injectors are fitted inside the engine where at one time they were bolted or clamped into the cyl head where a spark plug would have been fitted on a petrol engine.
Not only did this make the removal and refitting of injectors for periodic cleaning/overhaul easy, you immediately noticed if there was any seepage from the injector seal and even if left it wouldn't do any great harm unless long term.
Now that injectors are inside the engine, any such leakages can go unnoticed for years, but the carbon blow by gets into the engine oil and not only gets deposited around the oil galleries especially on vehicles which don't see regular oil changes and that carbon can and does congeal in the oil pick up filter leading to total engine failure.
This is exacerbated by the modern trend to suck the oil out instead of draining properly.
The big advantage to a long overnight oil drain is that depending on sump design you can inspect either with the naked eye or by use of an endoscope the oil pick up strainer for signs of contamination, early warning there might be issues.

I don't get this almost bible like adherence to the ridiculous oil change intervals now suggested for some cars, circa 20k miles (i offer PSA 1.6 in evidence though its hardly alone), changing the oil regularly is probably the cheapest and best maintenance a car owner can do for their car, cheap as chips if you buy your own oil in bulk packs when on offer and DIY, most cars its a matter of minutes unless you own a car with known possible issues where the oil pick up is best checked out after an overnight drain...note not the owners of 5 cyl Ford Ranger engines the pump of which apparently can't reprime its engine oil if left drained longer than 15 mins.

Talking of oil intervals, the leased truck i drive is on 100k kms service intervals, though in mitigation like most truck engines it has an oil splnner as standard and large truck sumps hold between 5 and 7 gallons of oil, it also uses about 2.0 litres of oil a month (some 11000 kms) so gets part of a complete oil change in between services, the oil spinner helping keep the filters healthy.

Another thing i'm unsure about, so many people driving modern Diesel cars claim to use no oil at all between services, which can be as much as 20k mile intervals, one wonders if they had the oil analysed at the end of 20k how much of that oil would be fuel that's blown by or in later engines due to failed regens, anyone tried this?

[Smint]

Craigie said:

Thanks for all your replies. I will speak to the indie today and try and get some more information.
What are the panels thoughts on second hand turbos ie from eBay/breakers yards? Worth the gamble?
I am being quoted around £1200 for a refurbished, year guaranteed OEM from a local Turbo specialist but there also seems to be some scrap type turbos from EBay for only a few hundred?

If you are going recon i'd be inclined to get the present one refurbished due to its known low mileage, you have no idea what another used one might been through.

Whoever does the job, suggest replacing any oil supply pipes the turbo uses, and drains the engine oil out properly and inspects the oil pick carefully via endoscope for signs of carbon or other contaminants, might even be worth whipping the top engine cover off and see what the valve train looks like for cleanliness.
We don't know what caused the failure for certain, but be assured allowing the engine to warm through before demanding too much of it, allowing it to warm down for a minute or three depending on what sort of driving immediately before stopping, keeping the oil topped up and regular sensible oil changes will see it has the best chances of lasting a long time.

[pointer7]

Could be a number of things I guess, mainly bad seals in the turbo, overfilling of oil and then the dreaded runaway!

As a preventative measure, I always let my car idle for 30 seconds after I stop before switching off to keep the turbo supplied with oil until it slows down....