Clean Turbo

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mooseshaver
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Post by mooseshaver »

I've been using Expensive Fuel mostly as I did think at first it ws related to some cheap fule I decided to put in quite some time ago.
The one for the air intake goes in the turbo after the flow airmass sensor. Will see if a family member can help me with that this weekend
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Post by wheeler »

citrojim wrote:
mooseshaver wrote:Had a previous post somewhere about anti-pollution fault. Cit Dealer think the trubo needs replaced as the Eolys builds up in the turbo. But I've been told that turbos can be cleaned.
There is a place in Kendal that will do it for around £300. But tis a bit far. A new turbo fitted from Citroen is £1060.
Surely the Eolys burns in the particulate filter? It is hard to see how it could cause a mess in the Turbo. In fact, the Eolys (if I understand correctly) is ignited in the particulate filter by making the exhaust gasses very hot for a short while and this very act would help burn any deposits out of the turbo turbine.
The eolys fluid is mixed with the fuel so it will eventually end up in the exhaust & therefore the turbo aswell, the eolys fluid reduces the temperature at which the soot burned off at but does not burn itself.

The anti pollution warning is just the same as the engine management light & there are lots of things that bring this warning on, nearly any sensor fault will effect emissions & caus the warning to appear.

Remember when these turbos fail they default to full boost so if the turbo is failing it will boost too much therefore give the too high pressure fault that is coming up.

Then again it could just be the turbo electrovalve stuck open.........
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Post by KevMayer »

The turbo on a C5 2.2 Hdi doesn't have a waste gate like a Garret or KKK turbo. It has a vacuum actuated solenoid which pulls on a shaft.

The power turbine spins inside a cylinder. The vacuum actuator pulls the shaft to move the cylinder to vary how much of the power turbine is exposed to the exhaust gas flow.

At low speed the cylinder covers most of the power turbine to leave just a short section exposed. Exhaust gas flowing through this small gap flows at high speed and makes the turbo spin fast resulting in high boost pressure.

As the boost pressure increases, a pressure switch detects the increase and the vacuum solenoid is activated and pulls the shaft which draws the cylinder away to expose most of the power turbine.

With most of the turbine exposed the gas velocity is reduced and the boost pressure reduces.

Now, if a build up of something, say Eolys oil ?, prevents the cylinder from moving then only a short section of turbine is available all the time. The very high exhaust gas speed flowing through the small gap causes very high turbo boost. Your engine sees an overboost and gives the Anti Pollution Fault.

The turbo is shown on this site:-

http://www.citroenet.org.uk/passenger-c ... tech3.html

Cleaning the turbo will probably restore the movement of the cylinder over the power turbine.

cheers,

Kev
Cheers, Kev

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Used to have:- Xantia 1.9 TurboD SX. 1996 Blue & 1998 Silver Activa. + 1992 BX TZD Turbo.
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Post by mooseshaver »

KevMayer wrote:The turbo on a C5 2.2 Hdi doesn't have a waste gate like a Garret or KKK turbo. It has a vacuum actuated solenoid which pulls on a shaft.


Kev
Thanks Kev, all very usefull, it looks like a clean mighth fix my problem.
Is the lack of waste gate the reason 2.2 turbos don't whistel as much as other cars, like vauxhall's? Not important just wondered.
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Post by CitroJim »

This is most interesting and I can see now how a clean will help these turbos. It won't take much carbon and rubbish to clog up this sliding wastegate :shock:

I wonder how possible it is to take one apart to clean it. On the face of it, it should not be difficult and looks, from the picture, that it can be done without disturbing the turbine.

Whistle. Now Personally, I don't think the design of wastegate really makes much difference. A whistle usually means a bit of pressure is being lost somewhere. None of my TD turbso ave ever whistled and nor does my petrol turbo. You can hear them whining a little but this is purely down to the mechanical noise of the shaft, turbine and compresser impeller rotating at very high speed.
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Post by Kowalski »

citrojim wrote: Whistle. Now Personally, I don't think the design of wastegate really makes much difference. A whistle usually means a bit of pressure is being lost somewhere. None of my TD turbso ave ever whistled and nor does my petrol turbo. You can hear them whining a little but this is purely down to the mechanical noise of the shaft, turbine and compresser impeller rotating at very high speed.
The whistle on a turbo is caused two things, one is the vanes passing through the jet of exahust gas that is fired at the turbine, the other is the pressure waves coming off the impeller and hitting the outlet on the high pressure side.

You may think of the gas flow going through the turbo as being smooth but the impeller and compressor of the turbine both have vanes and the vanes cause pressure "surges" at an enourmous frequency, hence the whistling noise.

I have two Xantias, one with a KKK turbo and one with a Garrett, one whistles and one is silent, off hand I couldn't tell you which is the Garrett and which the KKK, but the newer ones turbo is quieter.

Kev your description of the "variable nozzle" turbo is quite good, but you've missed out on one little point. The point of the variable nozzle is partly to control boost as you've described but, it's also to increase low rpm boost.

At low RPMs the turbo hasn't got enough exhaust gas flowing through it to produce lots of boost. The variable nozzle reduces the compressor area to keep the gas pressure high and to keep small gas flow going at high speed, thats what means a larger turbo can be fitted because its able to produce boost at low RPMs and a larger turbo can produce enough gas flow to boost at high RPMs, thats part of what allows newer diesel engines more power at high RPMs. Of course you could fit a smaller turbo to an engine to try to acheive the same thing, but you'd have to run it at ridiculous speeds to get the high end boost so it wouldn't last very long....
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Post by CitroJim »

Kowalski wrote:
Kev your description of the "variable nozzle" turbo is quite good, but you've missed out on one little point. The point of the variable nozzle is partly to control boost as you've described but, it's also to increase low rpm boost.

At low RPMs the turbo hasn't got enough exhaust gas flowing through it to produce lots of boost. The variable nozzle reduces the compressor area to keep the gas pressure high and to keep small gas flow going at high speed, thats what means a larger turbo can be fitted because its able to produce boost at low RPMs and a larger turbo can produce enough gas flow to boost at high RPMs, thats part of what allows newer diesel engines more power at high RPMs. Of course you could fit a smaller turbo to an engine to try to acheive the same thing, but you'd have to run it at ridiculous speeds to get the high end boost so it wouldn't last very long....
Most enlightening Kowalski :)

So in effect, the turbo has a variable A/R ratio then. Very clever! It all makes sense now...
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Post by Fella »

C5 2.2 hdi. Going back to previous threads regards ESP faults etc. my car suffered from them before the turbo blew. Incidently the turbo blew open a welded seam which indicates the pressure involved. I still have the blown turbo as I was hoping to use as evidence of a manufacturing defect and tried to get some recompense from Citroen without success.
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Post by KevMayer »

The turbo on my 2.2 Hdi has a very loud whistle at low engine speeds.
The whistle seems to disappear at just over 2000 rpm.

At just over 2000 rpm is the point when the butterfly valves open to change the variable inlet manifold ducting from the swirl to the tangential gas route.

I'm not sure at what point/pressure the turbo geometry changes.

Kev
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Post by jmd »

From recent experience with my son's C5 2LTR Hdi this "Anti-Pollution Fault" can be caused by a number of things. One of which (in my case) was the pressure switch situated in front of the Air Filter, this "switch" fits into the Inter-cooler Pipe, and is connected to a 2wire plug. It is easily damaged if removing the cover from the Air Filter. Check it, it is a rather fragile switch. Fitting a new one in my case cleared all faults, Anti Pollution Fault The Service message, and Limp Home Mode. All three were showing, together with the fact that I couldn't go over 2.000 RPM. My Xantia 1.9 Turbo Diesel has covered over 250,000 and thankfully no Turbo problems, so I doubt if your turbo is at fault.
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Post by mooseshaver »

My brother knows someone who is prepared to clean the turbo. He is used to cleaning the wastegate on VWs which often have a similar problem

Also my Dad and brother disconnected a pipe and began spraying the cleaning stuff in it. Unfortunatly it appears the air intake they chose sucks and blows, so jsut blew the stuff back out again.
Made a nice loud noise when revving with the pipe off, if I was a boy racer I would have left the pipe off.
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Post by mrbump »

Just my 2p's worth:

The VNT turbo has no 'cylinder' wastegate. The text refers to the bleed soleniod which controls the amount of vacuum that the actuator sees. Same as any pneumatic valve. It is not this that is affected by any crud buildup.

The VNT turbo operates by effectively obstructing the flow of gas into the turbine housing. Best analogy is that of one putting ones finger over the end of a hosepipe to get a jet. When the boost pressure as required is met and sensed by the ecu, the 'finger' is removed and hay presto, high flow, low backpressure.

This is achieved by a sliding ring wich sits inside the turbine around the base of the wheel. As the actuator acts on this wheel, it turns it. The wheel has cutouts for little arms which control about 12 'vanes' that look just like little areofils. These then divert the flow either onto the turbine blades or move out of the way and allow full unobstructed flow. You can see this in the pic of my VNT opened up below:

Image

All that happens is the blades get coked up and stop to move. Usually in the high boost postion. It may not need the turbo opened up to clean them. Just disconnect the wastegate arm from the lever on the center catridge of the turbo and move it fully from open to closed positions until it feels 'free' again.

Any turbo shop who is quoting £300 to do this will also be giving the turbo a rebuild, although I have known turbos just to be dismantled and put in a parts washer and still charge the rebuild fee if all checks out ok...
:?

Hope this helps... :D

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Last edited by mrbump on 20 Mar 2007, 21:42, edited 1 time in total.
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Post by mrbump »

Hmmm,

After proper inspection of the diagram properly it seems as if there is a different method used to actuate the vanes on the hdi turbo compared to the VW one I have. It seems there are 2 considerations here. The cup (sorry kevmayer i see what you mean now!! :oops: ) shaped object covers the turbine blade and reduces the gap that the exhaust gas has to flow through, also the vanes are moved in this same movement.

The same applies though, remove the actuator and move by hand till free!!

Makes me wonder why they have used both methods, i mean the VNT style vanes and also a variable entry system as well? Most likely why these turbos dont seem to last so long....
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Post by KevMayer »

No problem mrBump.

I see you have a ZX turbod and you say it now has VNT. Thats intersting, what did you do to it ?

cheers, Kev
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Post by mrbump »

kev

I ahve done a fair bit to it, had a thread a while ago.

http://www.frenchcarforum.co.uk/forum/v ... highlight=

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