Turbo weak, some questions

[D.Slatford]

Hey all, I've changed my Xantia again, this time for a new style, 133K 1.9TD. It's rather nicer than the earlier models! It's had a ton of work done in the last year too (head gasket, abs sensors etc).

However, the engine is definately less powered than my last ~160K TD. The turbo does work (I can hear it say, in an enclosed carpark when the walls reflect the noise) but otherwise I can't hear a thing. My previous TD had a much more noticable whistle after 2000 RPM. I seem to be putting my foot down harder too, and when the turbo does kick in, I can't really feel it (again, my last TD 'took off' when the turbo ran). There doesn't appear to be any smoking.

Now, there might be an air leak. With the bonnet up, revving the engine, there's a quiet but definate hissing somewhere down in the corner near the alternator side of the intercooler, that I can hear over the engine. I don't know which way the air flows through it, should I normally hear any 'hiss' from one side or the other? I would imagine not, but I don't know for sure. I do assume any air leak at any point will reduce the performance (and sound) of the turbo? If this seems like the culprit, I'd love to know if there's any handy tips for confirming the diagnosis, or more accurately locating it!

[406 V6]

If you have a leak from the intake side, with the turbo boosting, you should ear something like pushing the air out of you mouth with the lips in the "U" sound positions and you tongue in the middle (this is the best i can think of). Or like a bladder pushing the air out
you should have arrows pointing the airflow on the intercooler; from there you can check all the pipework for leaks.

[jeremy]

There are 2 elements to turbo boost, one is the supply of high pressure air to the engine, the other is additional fuel.

On you old TD there was a pipe from the high pressure side of the inlet system (between the turbo and the engine - probably from one of the pipes running to the intercooler) which ran to an additional fuel device on the injection pump (top for Bosch, radiator side for Roto-Diesel). It is very common for that pipe to split or simply drop off - and you have an instant conversion to a non-turbo engine.

Your new car may have a partly electronic pump but probably has a similar device. Your first stop should be to see if that is in place.

Has anyone been tinkering with the engine recently? If so not only may they have dislodged the pipe but they may have messed up an air hose and split it when joining it - and caused an obstruction. This would be a rubber to steel pipe joint.

[Kowalski]

Your new car may have a partly electronic pump but probably has a similar device. Your first stop should be to see if that is in place.

The setup on the later engines with the electronics in the pump is pretty much the same as the older ones with the pure mechanical pump. The electronics on the pump only control the timing advance, they don't do anything to the fueling.

[nick]

With the bonnet up, revving the engine, there's a quiet but definate hissing somewhere down in the corner near the alternator side of the intercooler, that I can hear over the engine.

When one of the intercooler pipe connections on mine came off that's exactly where it did it - where the large rubber hose fits onto the end of the intercooler down near the alternator. When looking at this pipe from above it can look as if its connected properly, even when it isn't. It tends to work loose at the bottom so to all appearances it looks ok, but most of the boost pressure leaks away through the gap and you get a whistling/hissing noise from that corner of the engine bay, and very reduced acceleration.

[D.Slatford]

Well, all appears to be fine with the air ducting. I have noticed two things, one very worrying:

The head gasket was changed about 10K ago. However, there's some oily sludge appearing in the water (no cheese and nothing under the oil cap). Not happy - I may well have been sold a dud. Or, is it possible this is residual oil running through the system from a previous failure? Otherwise I guess it was a botched job, or cracked head, or something else terminally expensive Which would be a shame, as literally everything else works fine on this SX, itself something of a rareity in my experience!

Secondly, there's this device, connected by a cable to the fuel pump, and air hose to two more devices:

http://foxhosts.co.uk/pics/xantia_iv/DSCF2981.JPG
http://foxhosts.co.uk/pics/xantia_iv/DSCF2983.JPG

I don't know what it does, but whether the car is hot or cold, the cable doesn't budge at all. I recall from my last TD it moved when revved. Is this part of the turbo in any way, could it be a cause or a symptom of the problem?

[AndersDK]

Oil in the coolant is un-avoidable after repairs.
More often than not its just there.

From many owners reporting here - and my own experience - the XU/D engines will overpressure the cooling sytem on bad HG's. They do not do the old fashion oil in coolant - or greycolouring of the engine oil.

The cable thingy I believe is the coldstart device. Should come from a cylindric device fitted in the thermostat housing.
The electro valves I believe is part of the EGR system - which lowers emission values.
These dingies has nothig to do with the turbo at all.

Dont think you have any worries really

[RichG]

The things in your pictures are the fast idle / cold start devices.

The first picture shows the diaphragm and the second the 2 electrovalves. One should be green and one blue. From the vacuum pump on the end of the camshaft a pipe should run to a tee-piece. Each end of the tee is connected to a separate valve. One valves outlet goes to the diaphragm and the other valves outlet disappears behind the engine to the Exhaust gas Recirculation valve. If ANY of these pipes become disconnected then the engine will run at a fast idle all the time. If the device is working correctly then the cold fast idle should be about 1050 rpm and the hot idle about 950 rpm. When the aircon is used (if fitted) then the idle speed should increase up to the cold fast idle setting. If all the pipes are intact and it is still not working then the idle elctrovalve is duff. This is quite common and easily (if not cheaply) fixed by replacing the valve. I have done this on mine once.

Hope thishelps.

Richard

[D.Slatford]

Thanks for the replies guys! I had a feeling that was something to do with cold start.

It does idle a bit fast - around 1000RPM, although if it's meant to idle at 950 then it hardly seems a big difference.

I'm hoping the oil in coolant is just residual crud from the gasket change. It did seem to loose a bit of water though, unless that just evaporated off and found its level, it's too early for me to tell (or maybe it rises and falls with temperature). I could never be sure exactly where the correct level is meant to be on those resevoirs. It's dropped to a bit below the two cut-out grooves in the side of the plastic thing under the cap, which is about where it was when I topped it up two days ago.

[Kowalski]

Secondly, there's this device, connected by a cable to the fuel pump, and air hose to two more devices:

http://foxhosts.co.uk/pics/xantia_iv/DSCF2981.JPG
http://foxhosts.co.uk/pics/xantia_iv/DSCF2983.JPG

I don't know what it does, but whether the car is hot or cold, the cable doesn't budge at all. I recall from my last TD it moved when revved. Is this part of the turbo in any way, could it be a cause or a symptom of the problem?

The first is the device that controls the fast idle, when the engine is cold or you have the air con on the fast idle should be activated (approx 900 rpm). Once the engine gets warm (approx 60 C) the slow idle should be activated (approx 800 rpm). Like you said, when the engine is revved the diaphragm should move, the engine seems to use the raised idle speed as an anti stall when the engine is hot, and seems to deactivate it when the engine is revved and cold.

The second thing you've pictured is the pair of electrovalves. One controls the idle speed, the other controls the EGR. If your idle speed isn't working properly, there can be one of two faults. Firstly, the electrovalves can and do fail, I've had to replace one on my car, the coil on mine went open circuit you can check for that with an multimeter. The other fault that occurs is that the little pipe that goes to the EGR valve goes hard, splits then comes off the EGR valve, this dumps your vacuum to atmosphere so even if the electrovalve worked correctly it has no vacuum to operate the diaphragm, this has happened to my car too.

[Dave Burns]

Tip. Your car is better off without EGR, just pipe up the vacuum pump to the idle speed electro valve and diaphragm.

If the blue idle speed electrovalve is shot, i.e doesn't click when energised then you can use the green EGR electrovalve instead, all you need to do is shave off the mating rib on the inside of the socket, the blue plug will then connect to it.

Both valves function the same, the only difference is the position of the mating rib to prevent the wrong plug being inserted.

Note that the valve will not work if the vacuum supply goes to the wrong port on the valve.


Dave

[D.Slatford]

Thanks to all for your help. After new oil today and a good run with injector cleaner it's quite clear the turbo is working fine afterall

The electrovalve connected to the cold-start diaphragm is open circuit, so I'm looking for one of those. Connecting the vacuum pump direct to diaphragm somewhat slows the idle speed.

As for the oil, it does seem just scum on top of the water, seems I probably don't have much to worry about (touch wood), time will tell if the water disappears on me!