hi...you get a whistle when a big chunk of a vane is missing......looking at them pics some debris as got in from somewhere and destroyed the compressor wheel.....cannot think how unless it lost a big chunk off a vane and did that

heat wise......they dont get anywhere near as hot on a diesel and that colour and contition of the vnt mechanism looks as you would expect it to look

do they not make a cat by pass kit that you could try........

 

think about a cheap diagnostic lead and try some free software like multiscan when you run after repair.
turbo vanes look to have been in fully closed position judging by the shadow on the vnt ring.
this with any sort of full throttle I would expect to create high egt and overheat the turbine.
also this would create the overboost.
you want to check and confirm the vnt actuator works correctly and then the vnt solenoid also if it has one could be stuck in max spool position giving full vac to actuator all the time.
theres no way the turbos been assembled wrong or the vnt stop screw adjusted ?
when the turbos assembled again you need to confirm the vanes are free to move actually do with vac applied and removed.
with same issue twice id say vac supply to vnt actuator more likely issue a cheap vac gauge and some tubing and a vac pump or large syringe should suffice to test the control side.
you could run it with cat missing as is to test but if vanes are still closed your problem will only get worse with a more free flowing exhaust.
some info in here would be of help regarding vnt vac tests
http://www.alfaowner.com/Forum/alfa-147-156-and-gt/686993-fault-code-jtdm-p0237-3.html

 

I have a kkl cable from long time ago.
The stop screw was unstouched at first. I mean, the turbo was very slow to spool, so I tried lowering the screw few months later.
As I say, the turbo pressure was very irregular over the rev range. Maybe 0.3 boost at 1700rpm, then 0.7 bar at 2400 and quickly started to rise up to 1.4bar at 3000rpm.
That makes me think that the turbo was bad adjusted, or the clogged cat was causing this?
When I had changed the turbo core, everything moved freely, although due the bad boost it moved only when the engine was at high revs and high load.
Then the car was stalled for 3 months (strange noise like clapping valves that nobody knew to fix until someone looked at the camshaft and replaced it), and since then the overboost started to appear.
I guess the turbo had rusted inside for being unused all that time. But when I opened it it was when I found it was knackered!
There was no changes, all was the same. This turbo has pressure actuator, instead vacuum.
The pressure that the turbo makes, moves a pneumatic actuator that pushes the geometry.

http://i49.tinypic.com/jaj777.jpg

So, in "idle" state, the geometry runs in max boost position. When the pressure raises, the actuator starts to move, to maintain a continuous pressure of 1 bar.
Even at the minimum the vanes don't touched the turbine, I guess that if the vanes had touched they should look grinded and not only a little bent?
Anyway, now I got a complete turbo. So it should have any problem related to the actuator or geometry.

Definitely I'll empty the cat. So, are you sure that that wasn't overheating?

 

not sure of anything ?
if its already off the car I think id be bashing the cat out anyway, if your turbo troubles are over it should help free up a few mpg and help turbo spool quicker , if turbo troubles are gone that is?
ive no experience with the older pressure actuators or your car, but in the same way you need to test that turbo before fitting so your confident that the vnt operates as it should, so with an atained boost pressure of 1000mbar it should have turned the vanes to fully opened ? or just be opening ?
is there any chance the pipe from compressor housing to vnt actuator was holed and not opening up vanes ?
be very wary of altering the stop screw its been set there for a reason.
that last pic you've posted if its your old turbo looks like its been getting some foreign object damage to the leading edge of the compressor wheel, that wont have helped with its performance or efficiency, also due to the damage on the turbine wheel I would guess it had also lost most of its efficiency especially a low revs low load, when the revs and load got up it would catch up id expect.
id want to slip that hose off the compressor housing and apply pressure to test that actuator with a gauge t'd in to see what pressures it moves at before fitting to car.

 

Nope, the last picture is taken from the Web .
Mine was perfect , in both turbos.
Instead of "are you sure?", I'd better say "is it very rare that diesel overheats and melt the turbo?"
Regards

 

Finally I did it all. New turbo and empty cat.
The engine seems smoother and revs better, I noticed that the engine noise in 4-5k revs is much snoother than before. For bow I just left the car idling to burn all the oil that comes in the turbo intenals and housing.

After 20 minutes or so all was hot and clean, I tried some reving and tomorrow I'll do a testing drive.
I was curious and made photos of the exhaust ports of each cylinder.
Unfortunately, I found something that I'm pretty sure caused the first turbo break.
Is it a valve guide with a bit off?
https://dl.dropboxusercontent.com/u/23958662/turbo/Screenshot_2014-11-29-23-22-31.png

I'd definitely say that the second turbo was damaged by me when touching the stop screw. Do not do it folks!

The car starts perfect even on cold mornings,and idles nice, so I think compression is ok

 

Purely out of curiosity, what plans have you to deal with the broken valve ? I'm thinking that is going to continue breaking up, which in turn will damage the turbo again. Anyone have an idea how it broke in the first place ?

 

yes that piece of valve guide casting would have definitely done some damage.
it could have even got jammed in the vnt vanes and jammed them in closed position.
the newer vnts are ok up to 850c or even 950c but no idea about the older type like yours but im pretty sure if its aluminium it would have melted long before the turbine tips.
you could do with a bit of logging now on boost control desired and actual before you go mental reving up into 4000-5000revs.

 

the nozzles are steel, even on the TD2503V

there's no boost control though, the turbo tries to reach 1 bar +- 0.1 bar. go over and the vanes close, underand they will open. the actuator is the same as the ones used to open a bypass on a petrol turbo.

 

I usaully run a strong dose of cataclean through the motor for 50miles minimum after a turbo failure. That stuff works good, but in your case you done wise to change/remove the cat that has been tortured by long term oil contaminants. You said hot, did you feel it on you're face?

 

I know the nozzles are steel or most likely stainless steel, I was referring to the broken head casting being aluminium and melting before the temp was high enough to melt the turbine wheel tips, a high temp alloy of steels or Inconel on newer turbos.
and I meant to log and observe that boost is "in control" and not still overboosting, not as we would call the vnt boost solenoid "control ".

 

the MAP sensor fitted is 2.5 bar, and the turbo is capable of delivering 1.4 bar boost reliably. so a check of the MAP sensore would be needed. 1.5 bar boost throws an overboost warning.

 

I drove her today. Surprisingly, this turbo performs worse than the damaged one!
The new turbo looked amazingly clean and new:
http://oi57.tinypic.com/v8hher.jpg
http://oi61.tinypic.com/2nkuudv.jpg
http://oi61.tinypic.com/2rpxs3a.jpg


This is a graph with the old turbo. As it's seen the engine was dead until 2100rpm, when suddenly all the power appeared.
http://i61.tinypic.com/168hl01.png

This is a graph with the new turbo. The pressure actuator works great, limiting the pressure to 1bar very well without spikes or overboost. But it doesn't have any power until 2600rpm, just like the old but in a higher rpm range.
http://i59.tinypic.com/343ofax.png

I'll contact the guy that made the turbo. I guess the actuator is bad adjusted, maybe it only needs two turns on the stop screw, but I won't play with fire again :cheese:

 

is it more likely to adjust the actuator rod ? than the stop screw , on this type of turbo.
if the guy you bought it off agrees maybe try turning the rod 1 turn and log again(if you can get to it)
also what sort of maf values has it got? any chance its reading low and holding back on fuel.
tried unplugging maf ?
looks a nice condition turbo though.

 

I'm confused. The turbo is always in the stop screw position, until some boost is achieved and the actuator starts moving to reduce the boost.
So, doesn't the stop screw adjust the position where the boost is best for low flow gasses?
Enlarging the actuator rod would only get it worse, as it would start moving earlier and thus reducing boost earlier.
Am I correct?

 

The maf is bosch original with 600 miles on it. Costed 120 euro! (£95)
He answered today and suggested to turn down the stop screw 1-2 turns.
Hoping the best!

Edit: I did 1 turn and traveling back from the work it was better, similar to the old turbo. I'll do another turn later and test again.

At what engine speed is it supposed that the turbo should achieve full boost? I guess it was 1600-1700rpm, but I'm not sure now.
Cheers

Edit* It was the actuator not the stop screw! I have put it back to its original position.

The picture that he had sent looked blurry on the Phone's Ebay app! In the computer the image was clear and aimed at the actuator. Damn it!

Luckly I had only traveled 1-2miles on the city, and I did just two or three accelerations. I hope nothing broke !!

 

im not familiar with this turbo or actuator functionality.
id bet youd get more info or advice in the tuning section for how to set up this actuator and what sort of pressures it should spike to and maintain.
but as I would expect it to work, yes vnt vanes would sit at the maximum spool position under no boost pressure on compressor side, the vnt arm resting against the stop screw.
the stop screw is factory set in the best position for efficiency and flow etc as too much more closed vanes may actually choke the turbine flow and starve the engine breathing maybe?
if the actuator arm is adjusted (longer or shorter) it should affect how much the vanes open to the point where the actuator has done all its movement and vanes are fully open at your max boost pressure.
say the rod is now too long(guess) with minimal pressure its already starting to open vanes and too open at max boost, looking at the last log you only just get over 1bar boost at the initial spike and from there on are dropping below.
in the vw tuning forums(where they seem to play with actuator rod lengths more) they seem to expect an initial spike and then the lower boost is what they work on.
so is yours supposed to be say 1.2-1.3 bar spike and down to 1bar at say 4000rpm?
does the ecu give a desired boost pressure figure that can be added to a log
try 1 full turns and log again. then another turn and log.
edit
ive had a quick scan for a boost map from an ecu file and this may be a boost map off a 2.4 136hp(166)
View attachment 426249
in the right column looks like max boost at revs down left axis and across top is fuel .
so looks closer to
1000rpm 1280mbar
1300rpm 1568mbar
1600rpm 1960mbar
1900rpm 2066mbar
2200rpm 2065mbar
2500rpm 2080mbar
2850rpm 2070mbar
3100rpm 2045mbar
3500rpm 2025mbar
4000rpm 2000mbar
4200rpm 1985mbar
4500rpm 1970mbar
4700rpm 1700mbar
4800rpm 1572mbar
5000rpm 1445mbar
are expected figures at maximum fuel 56mm3(or mg?)
so maybe try to add this to a log also to see your at max fuel or close to it?(total injected fuel )

 

so looks closer to
1000rpm 1280mbar
1300rpm 1568mbar
1600rpm 1960mbar
1900rpm 2066mbar
2200rpm 2065mbar
2500rpm 2080mbar
2850rpm 2070mbar
3100rpm 2045mbar
3500rpm 2025mbar
4000rpm 2000mbar
4200rpm 1985mbar
4500rpm 1970mbar
4700rpm 1700mbar
4800rpm 1572mbar
5000rpm 1445mbar
are expected figures at maximum fuel 56mm3(or mg?)
so maybe try to add this to a log also to see your at max fuel or close to it?(total injected fuel )

this seems to follow the torque curve for a 136, but I'm unsure why these values are in the ecu as the only way to control the boost is through the fueling...

 

Thanks for the tip!
Was the gt2256 easy to mount? Did the turbo match the exhaust?
You used the pressure actuator from the td2503 on that turbo, right?

Edit. I did 1.5 turns on the stop screw.
As you can see, the boost is much better
https://dl.dropboxusercontent.com/u/23958662/NEW_TURBO/1,5_turns_Stop_Screw.png

What I don't understand is the low intake air quantity. The maf is Bosch new.

 

the turbo matched the exhaust manifold, but I made a custom downpipe from 2 90 degree bends and matching flanges. I believe I also ordered a new oil feed pipe for a 20v.

you're still late to make boost though, I truly believe you should aim for what sussexa posted:

1000rpm 1280mbar
1300rpm 1568mbar
1600rpm 1960mbar
1900rpm 2066mbar
2200rpm 2065mbar
2500rpm 2080mbar
2850rpm 2070mbar
3100rpm 2045mbar
3500rpm 2025mbar
4000rpm 2000mbar
4200rpm 1985mbar
4500rpm 1970mbar
4700rpm 1700mbar
4800rpm 1572mbar
5000rpm 1445mbar


I remember the engine coming on song around 1500 rpm, pulling effortlesly even up the steepest hills in 5th (20%)

air quantity seems about 10% down off boost? did you already blank the egr valve?

 

Yep, the EGR is totally blocked, in both sides.
For testing purposes, I ran without the MAF and the driving was absolutely horrible.
Was like a 50hp petrol engine moving the 1350kg (3000 pounds) car, the power was completely linear.
So I think the maf is ok?.

 

yes maf is ok. you can see the maf readings correspond to the boost and don't lag behind.

how about engine timing?

 

I have to replace a pulley that has been doing more and more noise, I'll also tell the dealer to check that.

 

looks a lot better than before but a said still a touch late in the rev range, I still think the actuator rod would be where id try next ive no idea on that turbo , but tips of vanes can contact tips of turbine blades on some turbos if the stop screw is adjusted too far.
just as a spot check with ign on only what is map sensor reading ? close enough to atmospheric ? possibility the map sensor is over reading and therefore maf values would be less than expected. 50-80mbar might make a difference ?
other than that possible air leak after the maf before the turbo on the inlet pipe or crankbreather pipe maybe? the maf values don't look drastically low but worth checking.
try the actuator rod 1 or 2 turns to see if it moves the max boost up at all, the stop screw will only affect max spool position on the stop , once boost is reached and actuator opens vanes only adjusting actuator rod can alter max boost value ? it may bring boost up earlier in revs also?
did you log fuel quantity in any logs? if its not getting enough fuel theres not enough energy in the turbine to make boost quick enough to achieve say the 1.1bar before 1900rpm.

 

At idle it reads 1010-1020mbar (I live at sea level)
At a friend's house, who lives in a place which is at ~500meters over sea level, it reads 940-950mbar.

From this chart, it seems that MAP is OK.
It's in Spanish, but you only need to know that "metros" are meters and the rest is the same

 

Some news: I told the seller about the stop screw.
I sent him the graph with 1.5 turns, showing the great difference.
Also told him about opening the exhaust side and moving the stop screw until the clearance between the vanes and the turbine was 1mm. And he said ok!
Now I'll have to remove all the damn thing again .
Maybe next week. I don't have time enough to dismantle half car each weekend! :tut:

 

I just forgot to greatly thank you all for all the help :thumbs:

Just to be sure...vanes are closed for best spool on low revs, while it opens when the exhaust flow is high (high revs) to reduce the speed of the turbine and prevent overboost.
Is it right?

Just like this image:

Or this video:
http://www.youtube.com/watch?v=Gc2awh0O0Bc


If so, I don't understand how loosening the stop screw would cause damage to the turbo?
As doing so would close them even more.
There's no other way that the vanes touch the turbine unless the actuator pushes too much, right?

 

that's right. but make sure you don't fully close the vanes, leave about 1 mm open.