Thread: boost lost???

Originally Posted by uninformed

yes but....thats all I had so the 2 copper washers have been reused. I will keep an eye on it.

good info on the start up procedure.....should I do it now after I already started it (should have checked in first doh!)

off to give its first run

It will still be oily, it will be fine, dry bush on the turbine shaft is bad, but seeing as you've just removed it

VNT, will make less boost, high EGT's with non operational vanes, or no boost and higher EGT's depending on action of control and where it fails to, as you have found, also the whistle is awseome, when in the open position!!

Ill have to learn how to do that annealing trick one day.

well a definite improvemnet. feels pretty much like normal, maybe a little better than pre Friday's event. I would put that down to excessive play between the actuator rod fitting and the external plate. EGTS are much closer to normal with only getting up to 250c Post/T on a hard excelleration up to 80km/h through the gears and in to 4th, with it starting to fall a little when leveled out 80km/h. The more destinctive turbo whistle has now gone back to normal as well. This was only a 2-3km short run. I will do some more with inspections today.

nothing seems to be leaking at this stage. I will keep an eye on that banjo fitting. The turbo to manifold did not have a gasket??? and as for the 3 studs/nuts, well if it wasnt for my beautiful Snap-on Hi-po 0 offset ring spanner, I think I would still be trying to get those undone. Torque was set at FT!

the hardest thing for me doing this, was self-doubt. Not having the "feel" for certain things like bolt tightness etc...and it is always hard to tell when getting in for that first drive as being a bit worried, emotion comes into play and the senses are hightend, which is hard to remove that from logical judgment of the small things

thanks to all that chipped in a helped. Especially Rick for putting up with my phone calls

Originally Posted by uninformed

Ill have to learn how to do that annealing trick one day.

well a definite improvemnet. feels pretty much like normal, maybe a little better than pre Friday's event. I would put that down to excessive play between the actuator rod fitting and the external plate. EGTS are much closer to normal with only getting up to 250c Post/T on a hard excelleration up to 80km/h through the gears and in to 4th, with it starting to fall a little when leveled out 80km/h. The more destinctive turbo whistle has now gone back to normal as well. This was only a 2-3km short run. I will do some more with inspections today.

nothing seems to be leaking at this stage. I will keep an eye on that banjo fitting. The turbo to manifold did not have a gasket??? and as for the 3 studs/nuts, well if it wasnt for my beautiful Snap-on Hi-po 0 offset ring spanner, I think I would still be trying to get those undone. Torque was set at FT!

the hardest thing for me doing this, was self-doubt. Not having the "feel" for certain things like bolt tightness etc...and it is always hard to tell when getting in for that first drive as being a bit worried, emotion comes into play and the senses are hightend, which is hard to remove that from logical judgment of the small things

thanks to all that chipped in a helped. Especially Rick for putting up with my phone calls

For a dude who seems to raze people on the interweb often about being wrong, I'd of thought it would of been a doddle, I can understand the diagnostics can be a little daunting, but those repairs?

Anyhow, turbo to manifold should be fine, so long as there has been no deformation, its quite common to surface grind heads and manifolds and all things similar and run no gasket

Originally Posted by rovercare

For a dude who seems to raze people on the interweb often about being wrong, I'd of thought it would of been a doddle, I can understand the diagnostics can be a little daunting, but those repairs?

Anyhow, turbo to manifold should be fine, so long as there has been no deformation, its quite common to surface grind heads and manifolds and all things similar and run no gasket

yep, I will give a raze or 3 with things like opinion or if I feel miss information, but I dont remember giving anyone a hard time about having a go or doing mech stuff themselves, especially those that arnt trained. I normally take my truck to a LR mech as it is my only, AND work vehicle. I dont have the time nore want to miss somthing or do damage due to something silly like over/under tightening a nut/bolt etc. 50% of this stuff is principle and 50% feel from PROPER experience. I dont have anyone local that can really help me with this stuff especially a LR. I have 2 mates that are youngish ex mech's they can be helpful and then sometimes not know stuff I would. You may find it funny, but the LR mech of over 30 years, with a very good reputation didnt even pick up the problem after I was very clear about it, then when I informed him that it hadnt been resolved he wanted to adjust timing....clearly he felt the turbo system was fine. I doubt he checked the actuator at all. Hell it didnt take me long to find it with some internet help....and I thought it was a wastegate hahahaha

I was never around anyone mechanical growing up and never had someone tinkering etc

Sorry, I've only just got to this thread.
Of the 2 turbo pics that Ric posted above, the 1st turbo is mine. It is a genuine VNT (variable nozzle turbine, also known as variable geometry turbine) turbo for the same 2.8 litre engine that Serg has. That pic was taken before I fitted it to a 300Tdi in my old rangie.
To suit my application the compressor cover (housing) has been rotated a little to chage the angle of the outlet. Otherwise it is identical to the turbo that Serg has.
I still have the turbo (the rangie and 300Tdi have gone), but unfortunately it is in storage a lot of km's from where I am now, so I have to go from memory.
Reading the posts from the beginning my 1st thought was carbon/soot jambing the vanes or the vane adjustment mechanism.
To clear-up some matters in some posts:
These particular VNT turbos, as fitted to the 2.8 litre International engine, use a boost pressure actuator (same design as a wastegate actuator) to adjust the vanes (variable nozzle). A boost pressure signal from the compressor outlet is supplied to the top of the actuator can. The pressure acts apon a diaphram and as boost pressure increases to a preset pressure it will start to extend the rod below against a spring below the diaphram in the lower section of the actuator can. When these Garrett VNT turbos are fitted to most other engines the vane/nozzle actuator uses vacuum, which is easier to control by engine management computers. The modern diesels with VNT turbos and engine management computers also control the vane geometry to allow greater recirculation of exhaust gasses to reduce NOx levels, something not easy to do with a boost pressure actuator. No computer was ever used with the 2.8 International engine that Serg has.
The pics that Rick posted above showing the vanes and the mechanism that changes their angle is just as it is with these particular Garrett VNT turbos.
When boost pressure is low, the actuator adjusts the angle of the vanes so the turbine can produce more torque from the lower energy in the exhaust gas. Greater torque drives the compressor impellor faster so boost pressure increases (being a dynamic compressor, pressure is a function of impellor tip speed squared).
As boost pressure increases, and if the driver still has his/her right foot down, the fuel injection pump will increase the fuel injection rate and the increased mass air flow through the engine (from higher charge air density and engine speed) the energy in the exhaust gas rises significantly. In this state the turbine increases speed and the actuator will start to open up the vanes to control the turbo speed and reduce drive pressure (EMP - exhaust manifold pressure).
Now to the problem of adjusting the linkage from the boost pressure actuator. From memory, with this turbo, the spring in the boost actuator pulls the nozzle control lever against the stop screw. Also from memory, the length of linkage between the actuator and control lever is adjusted so that the lever is held against the stop, but starts to move away when boost increases (I don't know what this pressure should be for the 2.8 International engine).
If the length of the linkage is too short, more boost pressure will result, but there will be greater restriction in the turbine nozzle, resulting in greater EMP and turbine speed.
I would drive it as is, then if boost pressure is significantly less than it was before the control lever failed, I would shorten up the link from the boost actuator (knurled adjustment nut with lock nut).
If boost pressure is normal (or greater than before) and EGT is higher than normal, I would lengthen the link to reduce the exhaust flow restriction in the turbine (lower EMP).
The above assumes no other problem such as leak in the boost signal line between compressor and boost pressure actuators on fuel injection pump, and turbo.
Hope this helps.

thanks John, regarding the actuator setting in my situation, I was either setting it where it was or lengthening. both postions would have it against the stop at rest. I eneded up setting the lock nut where I could see a distinct soot mark above it, stoping cleanly on the thread. If I got my hole drilled in the actuator rod fitting, the same postion as original, then it should be the same as it was set up at factory. Currently it has the actuator with a little "pre load" on the internal spring (say 1 or 2mm) at rest. Unfortunately I was unable to get the factory/original set up due to the problem at hand. By the "seat of my pants" Dyno, it feels pretty close.

Hoses have been checked and all seem ok.

currently running ok.