C5 - Turbo Gone -30,000 Miles ???

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Post by fred1 »

Hi,

Could be you have a leak in the vacuum line that controls the variable vane operation on the turbo or the vacuum line to the VV has come adrift somewhere.

Had similar experience with a C3 1.4 HDi 16v (which is the same engine as the 1.6).

Suddenly lots of smoke and very lumpy. Then smoke cleared but tick over unreliable and power very much reduced. Things slowly improved over a few days but power stayed low.

Following extensive investigation I found a loose vac line down behind the back of engine, reconnected it and problems all went away. Been ok now for 10 months since the "incident".

The C3 doe not give out messages such as the anti pollution one. However, on the C5 these are often associated with over boost on the turbo.

the AP message is generic one with many causes. It is there to warn the driver that the engine is trying to operate in a way that will exceed the emissions regs! If it is an extreme excursion that might also damage the engine you will go into "limp home" mode to protect the engine.

Regards

John
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Post by Kowalski »

HDI wrote: Turbo's haven't become smaller , they are sized to suit a given application and that size is dictated by the airflow requirement of the engine in that application. EGT's are no higher now than than they were , I think you are confusing with pollution treatment gas temperatures created by FAP etc techniques , but this is after the turbo. EGT of diesels is lower than petrol engines by about 100 deg C. As a consequence turbo's on diesels should have a longer life but the lower EGT can be partially mitigated by the tendency of diesel turbo's to have a higher duty cycle.
I'm afraid I don't agree with you here, I firmly believe that turbos have been getting smaller for a number of years, the thing driving them to smaller sizes is reducing turbo lag, a small turbo will spool up more quickly than a larger turbo but to produce the same airflow as a larger turbo it must spin faster.

As an example, the XUD9 (1.9 TD, 90 BHP) came fitted with a range or turbos, one of which was the Garrett GT1549. The DW12 (2.2 HDI 136 BHP) came fitted with a Garrett GT1549S turbo. The numeric part of Garrett's naming scheme for their turbos represents the size, e.g. 49mm compressor wheel on the GT1549, so while the turbo hasn't changed in size, the power has gone up by about 50%.

Exhaust gas temperature is connected to the power output of an engine, the more work your engine is doing, the higher the exhaust gas temperature will be. In the past, large diesel engines (e.g. ship engines) would have a thermometer on the exhaust manifold corresponding to each cylinder, this was so that you could balance up the cylinders and have each one doing it's equal share of the workload. This method of calibrating the individual injection pumps relied upon the fact that the exhaust temperature went up when the load increased on individual cylinders. Now as I'm sure you're aware, the specific power outputs on diesel engines have been rising, e.g. the 1.9 TD produced 92 BHP where as the 2.0 HDI 16 valve engine can produce 136 bhp and is roughly the same size as it, my point here is that at full power a 2.0 HDI 16V will have higher exhaust gas temperature than a 1.9 TD, it is also worth noting that at full power EGR will be disabled.

Under normal cruise conditions, e.g. driving at 70 mph on the motorway, a power higher output engine will have no higher exhaust gas temperature than a lower output engine of the same size all things being equal. However as you mentioned in your post EGR does have an effect. At part load (and no load), the EGR system is activated and one of the things EGR does is to increase exhaust gas temperature.

Further aggrivating things, the turbo on my C5 (2.0 16V HDI) seems to have some sort of thermal insulation / heat shielding that the Xantia didn't have, so not only will the gas its exposed to be hotter than what the turbo on the Xantia was exposed to, it could also be getting less air to cool it, so it'll run hotter again.

There are a number of factors that mean current turbos are more highly stressed than they have been in the past and that in itself could be a reason for them not lasting as long as they have done in the past.
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Post by Peter.N. »

Sounds reasonable - yet another reason for running a '90s car :D
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Post by uncle buck »

Kowalski wrote:....one of the things EGR does is to increase exhaust gas temperature.
I think you will find that the whole point of EGR is to Lower the combustion temprature to stop the formation of NOx (nitrogen oxides)

Lower combustion temprature = Lower exhaust gas temperature.



Cheers.
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Post by HDI »

Kowalski wrote:
HDI wrote: Turbo's haven't become smaller , they are sized to suit a given application and that size is dictated by the airflow requirement of the engine in that application. EGT's are no higher now than than they were , I think you are confusing with pollution treatment gas temperatures created by FAP etc techniques , but this is after the turbo. EGT of diesels is lower than petrol engines by about 100 deg C. As a consequence turbo's on diesels should have a longer life but the lower EGT can be partially mitigated by the tendency of diesel turbo's to have a higher duty cycle.
I'm afraid I don't agree with you here, I firmly believe that turbos have been getting smaller for a number of years, the thing driving them to smaller sizes is reducing turbo lag, a small turbo will spool up more quickly than a larger turbo but to produce the same airflow as a larger turbo it must spin faster.

As an example, the XUD9 (1.9 TD, 90 BHP) came fitted with a range or turbos, one of which was the Garrett GT1549. The DW12 (2.2 HDI 136 BHP) came fitted with a Garrett GT1549S turbo. The numeric part of Garrett's naming scheme for their turbos represents the size, e.g. 49mm compressor wheel on the GT1549, so while the turbo hasn't changed in size, the power has gone up by about 50%.

Exhaust gas temperature is connected to the power output of an engine, the more work your engine is doing, the higher the exhaust gas temperature will be. In the past, large diesel engines (e.g. ship engines) would have a thermometer on the exhaust manifold corresponding to each cylinder, this was so that you could balance up the cylinders and have each one doing it's equal share of the workload. This method of calibrating the individual injection pumps relied upon the fact that the exhaust temperature went up when the load increased on individual cylinders. Now as I'm sure you're aware, the specific power outputs on diesel engines have been rising, e.g. the 1.9 TD produced 92 BHP where as the 2.0 HDI 16 valve engine can produce 136 bhp and is roughly the same size as it, my point here is that at full power a 2.0 HDI 16V will have higher exhaust gas temperature than a 1.9 TD, it is also worth noting that at full power EGR will be disabled.

Under normal cruise conditions, e.g. driving at 70 mph on the motorway, a power higher output engine will have no higher exhaust gas temperature than a lower output engine of the same size all things being equal. However as you mentioned in your post EGR does have an effect. At part load (and no load), the EGR system is activated and one of the things EGR does is to increase exhaust gas temperature.

Further aggrivating things, the turbo on my C5 (2.0 16V HDI) seems to have some sort of thermal insulation / heat shielding that the Xantia didn't have, so not only will the gas its exposed to be hotter than what the turbo on the Xantia was exposed to, it could also be getting less air to cool it, so it'll run hotter again.

There are a number of factors that mean current turbos are more highly stressed than they have been in the past and that in itself could be a reason for them not lasting as long as they have done in the past.

I will still have to disagree with u :)

Engine power has increased mainly due to common rail ecu controlled injection systems combined with conventional engine tuning techniques.
Turbo's are governed by by thermodynamic laws and fluid flow dynamics. To reach a given power output with a given engine requires a turbo with commensurate air flow capability. Which means that a compressor / turbine combination still needs to be of a size capable of delivering the required air flow at the necessary boost pressure within the constraints of it's efficiency map. There have been advances with aerodynamic design and turbine efficiency but nothing that dramatically reduces physical size.

EGT has to be controlled within the design limits of the turbo and this hasn't changed with the advent of increasing power. Diesel turbo's will be around 750 deg C and petrol around 850 deg C max. Any higher and the life of a turbo is proportionately decreased until the turbine melts !

Heat shielding on the turbine housing actually improves efficiency by maintaining the temperature at the optimum EGT. It also reduces radiated heat into the engine bay.

Many petrol engine tuners actually set up fuelling by mainly the EGT than by AFR or exhaust gas analysis. Obviously with an ear to det !!

I have been involved in tuning high power Jap cars for a number of years so this is something I have almost everyday contact with.
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Post by BX »

I believe turbo failure is a common fault on 1.6Hdi engines no matter what vehicle they are in (Pug, Cit, Ford Volvo mazda fiat suzuki). The failure is due to oil starvation caused by carbon crystalising in the oil. The oil feed arrangement on later engines was updated but im not sure from when.
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Post by Kowalski »

uncle buck wrote:
Kowalski wrote:....one of the things EGR does is to increase exhaust gas temperature.
I think you will find that the whole point of EGR is to Lower the combustion temprature to stop the formation of NOx (nitrogen oxides)

Lower combustion temprature = Lower exhaust gas temperature.

Cheers.
Lower combustion temperature can mean lower exhaust temperature all things being equal, but if you're comparing an engine with and EGR system to an engine without EGR, all things are not equal.

You're right that EGR does lower combustion temperature, it does so by in two ways. Firstly, the gas drawn into the engine has a lower density due to being hotter than ambient air thus has expanded. Secondly the gas contains water vapour which has a higher specific heat capacity than air, so as it is compressed it raises in temperature less.

The gas that an EGR system recirculates is exhaust gas which is hotter than the ambient air and if an engine draws in hotter gas, it's going to blow out hotter gas too, the fact that the combustion temperature is lower means that less heat will be transfer from combustion into the the block and head too. If less energy is lost to the engine block, its going to come out of the exhaust instead.

I am taking a somewhat simplistic view here, for example lower combustion temperatures can mean lower efficiency and that can mean more fuel needs to be burned for the same power output, having an additional effect on exhaust gas temperature, but even that in itself isn't completely straight forward..
HDI wrote: I will still have to disagree with u :)

Turbo's are governed by by thermodynamic laws and fluid flow dynamics. To reach a given power output with a given engine requires a turbo with commensurate air flow capability. Which means that a compressor / turbine combination still needs to be of a size capable of delivering the required air flow at the necessary boost pressure within the constraints of it's efficiency map. There have been advances with aerodynamic design and turbine efficiency but nothing that dramatically reduces physical size.

EGT has to be controlled within the design limits of the turbo and this hasn't changed with the advent of increasing power. Diesel turbo's will be around 750 deg C and petrol around 850 deg C max. Any higher and the life of a turbo is proportionately decreased until the turbine melts !
The point I was making about turbo sizes is specifically that turbos have not increased in size as horsepower has gone up, so a given size of turbo is now producing more power than it has in the past. I can give quite a good example of a "shrinking" turbo, as I mentioned above, some examples of the 92 BHP XUD9 1.9 TD came fitted with a GT1549 however, the HDI 90 2.0 8 Valve came fitted with a GT1546, which is a smaller turbo, granted the power output is 2 BHP lower (about 2%) but that's a 3mm or 6% drop in diameter.

Fundamentally, an engine needs more gas flow to produce more power and that gas flow has to be provided by the turbo. If the turbo has is not increased in size when an engine gets bigger the turbo will have to work harder to produce more power. As you've mentioned, there are fundamental limits on what a turbo can do but also as you approach those limits things have shorter lives. It was suggested earlier in the thread that turbo failures are becoming more common, all I'm offering is a potential explanation for that.
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Post by HDI »

Turbo's are heat driven by hot exhaust gas and that hot gas is provided by the engine. The compressed air delivered by the turbo allows more fuel to be combusted in the engine which in turn produces more hot exhaust gas which provides the turbine with power to drive the compressor and therefore compress air. This would be a runaway process eventually resulting in overspeed of the turbine and ultimately failure with the turbine and or compressor wheels exploding so control of speed and therefore boost is affected by the wastegate bypassing a proportion of the exhaust flow which balances turbo speed against required boost.
As long as speed is controlled , the boost pressure and EGT will stay within the design parameters of the given turbo and it's functional life will be normal.
The above applies to OEM turbo installations and should be considered accepted practice for normal applications to give reliable and durable service.
Things are different in the tuning world though ! Here turbo's are pushed to provide much higher boost so mechanical and thermal stress are increased dramatically. Boost on a family car is normally around 0.8 to 1 bar , but we often push boost to 2.2 or even 2.5 bar on high performance installations. Wear goes up due to much higher thrust on the bearings and rotational speed. Thermal stress is less of a problem though as time spent at peak boost on a 600-800 bhp engine is , quite brief on a public road !!

Turbo reliability on OEM installations should , if anything , be better than it was due to better materials and much better lubricants. If turbo's are failing prematurely there must be a problem with the installation design.
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Post by Kowalski »

HDI wrote:Turbo reliability on OEM installations should , if anything , be better than it was due to better materials and much better lubricants. If turbo's are failing prematurely there must be a problem with the installation design.
I'd agree that materials and lubricants have progressed, but the fact remains that turbo failure is more commonplace than it was in the past. There are more turbo charged cars around now than there were in the past (the growing popularity of diesel has caused this) but the failures are not specific to particular cars or even to manufacturers, they are industry wide. Perhaps you're suggesting that there is an industry wide problem with installation design and the fact that turbos are being pushed harder and closer to their limits is merely coincidence.
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Post by uncle buck »

Kowalski wrote: Lower combustion temperature can mean lower exhaust temperature all things being equal, but if you're comparing an engine with and EGR system to an engine without EGR, all things are not equal.
Yes we are talking about engines with EGR in this instance.
Kowalski wrote: ....The gas that an EGR system recirculates is exhaust gas which is hotter than the ambient air and if an engine draws in hotter gas, it's going to blow out hotter gas too.
I know this sounds logical but that's not how it works....because spent exhaust gas is included in the combustion burn the burn isn't as efficient so not as hot as it would be on pure air so a lower combustion temp is achieved.
Kowalski wrote: ....the fact that the combustion temperature is lower means that less heat will be transfer from combustion into the the block and head too. If less energy is lost to the engine block, its going to come out of the exhaust instead.
The combustion temperature is lower to start with so it will come out of the exhaust lower....it's as simple as that.



EGR does reduce NOx emissions however it increases hydrocarbons & soot particles are increased as the combustion process is cooler...hence the introduction of particle filters.

My theory is that EGR has something to do with the sudden increase of Turbo failures on modern Diesel vehicles.....it's an industry wide problem that seems to be happening for no apparent reason...something has to be causing the failures & my money's on EGR.


Cheers.
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Post by Kowalski »

uncle buck wrote:I know this sounds logical but that's not how it works....because spent exhaust gas is included in the combustion burn the burn isn't as efficient so not as hot as it would be on pure air so a lower combustion temp is achieved.

EGR does reduce NOx emissions however it increases hydrocarbons & soot particles are increased as the combustion process is cooler...hence the introduction of particle filters.

My theory is that EGR has something to do with the sudden increase of Turbo failures on modern Diesel vehicles.....it's an industry wide problem that seems to be happening for no apparent reason...something has to be causing the failures & my money's on EGR.
We're not going to agree about the hows and why's of EGR so I'm not going to argue with you about them.

I do agree that EGR has come along at the same time that turbo failures have become more common, so it's definately a suspect.

One thing that nobody has mentioned thus far is oil change intervals. The original XUD9 had a 6k oil change interval. That went up to 10k on the last XUDs and the HDIs. My C5 has a 2 litre diesel engine and a 20k oil change inteval, does that sound like something that could cause premature turbo death? In any case I'm planning on changing my oil more frequently than Citroen says I should!
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Post by Citroenmad »

BX wrote:I believe turbo failure is a common fault on 1.6Hdi engines no matter what vehicle they are in (Pug, Cit, Ford Volvo mazda fiat suzuki). The failure is due to oil starvation caused by carbon crystalising in the oil. The oil feed arrangement on later engines was updated but im not sure from when.
Thats very interesting, i wasnt aware of any common failings on the 1.6HDi until now. Though wouldnt more regular oil changes reduce the risk of this happening?
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Post by citronel »

I don't believe that turbo problems are something usual to all 1.6HDI engines; from engine configuration I think that this can happen more often to 1.6 + FAP in some specific conditions because turbo is very close to FAP filter.

I think that your problem is related to FAP problem & regeneration phase, because you mentioned that you heard often the FAN at high speed when you stopped the car and also the plastic shield under engine was melted.

For me this say that your FAP filter did not succeed to have a proper regeneration cycle when you drive the car, probably you drive the car in the city or for low distances, or other problems related to FAP system.
In short word FAP regeneration has to be done at ~600C for:
- at least 10' ( depend of FAP load )
- at speed >60km/h
- engine is hot (>60c )
- and you have >1/4fuel in tank.

Stopping the car/engine at this high temperature (600C) I think in time will destroy the turbo as it has no cooling and lubrication once engine it is stopped.

This is why I developed & installed for my car FAP sensor... if you need more info about my device Google it or ask me.

My advice if you hear the fan when you want to stop the car, don't turn the engine OFF until fan stopped, best is to keep driving the car as cooling it is better when car move !
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Post by ihatecars »

Just a passing comment, wow what an impressive and informative reply!!
Old-Guy wrote:As HDI suggests, the twin 'killers' of turbos are dirty engine oil and not allowing the turbo to cool down with the engine idling. Turbo bearing and seals depend on a good flow of oil to keep them cool - the exhaust turbine gets red hot - and particles in dirty oil abrade oil seal lips. Turbos whistle like miniature jet engines because they spin at similar speeds - tens of ..... ..brake on, hot disks cool unevenly because the pads locally retain the heat, progressively warping the discs.
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Post by JohnD »

Citroenmad wrote: Though wouldnt more regular oil changes reduce the risk of this happening?
It seems that Citroen UK are aware of the increase in turbo failures on 1.6 diesels in particular. They've issued this to dealers:-

OIL CHANGE PROCEDURE ON ALL DV6 ENGINES

It is necessary to follow a specific oil change procedure on all DV6 and DV6U engines so as to ensure that no used oil remains to mix with the new oil.

The following method must be used:

• The engine oil temperature must be at least 50°C :
- the engine oil temperature is considered to be at 50°C when the water temperature indicator is between 80°C and 90°C or the cooling fan has cut in
• ensure that the vehicle is level (side to side and fore and aft)
• remove the oil filter to allow the circuit to drain completely
• remove the oil filler cap and the dipstick
• remove the drain plug
• allow the oil to drain by gravity for at least 10 minutes (DO NOT USE SUCTION METHODS)
• fit a new oil filter
• refit the drain plug with a new sealing washer
• fill the engine with quantity of oil recommended for the engine
• refit the oil filler cap and the dipstick
• run the engine at idle until the oil pressure warning lamp goes out (about 1 minute)
• wait 5 minutes
• check the oil level using the dipstick: the level should be as close as possible to, but not exceeding the maximum mark (1) so as to be between (1) and (3)

For information, the lower mark (2) = Min (0%) the upper mark (1) = Max (100%) the intermediate mark (3) = ¾
4 of 4

CONSEQUENCES OF NOT KEEPING TO THE OIL CHANGE INTERVALS

If the customer does not have the oil changed at the recommended intervals, the oil will become excessively polluted and will no longer ensure the correct lubrication of the engine. One of the first consequences is inadequate lubrication of the turbocharger bearings causing a failure which is repeated after the turbocharger is replaced. Subsequent symptoms resulting from the reduced level of lubrication will be a noisy engine and then destruction of the engine.

We remind you that if the customer does not keep to the servicing intervals recommended in the Maintenance and Guarantee Guide, the customer will be responsible for the durability of the mechanical parts of the engine.
In this case, the any related repairs needed are not covered by the new vehicle warranty.

CONSEQUENCES OF NOT FOLLOWING THE OIL CHANGE PROCEDURE

If the oil changes are not done as described above, all deposits of old oil will not be removed and will very quickly pollute the new oil, accelerating the ageing of the oil in the engine lubrication circuit (even causing the oil to congeal).

The consequences for the engine are the same as if the oil change intervals are not observed. As a result, any related repairs needed are not covered under the new vehicle warranty.
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