First of all appologies to all for not posting this sooner (i did try a while ago but the site was down)
My solution to the TD4 power loss was in the end simple.
First i will recap my original probs which where (and if you have had these and spent loads of cash at the local stealers its best not to read past them)
1) loss of power around 55 onwards in 5th ratio (gear) your could feed the power in very gently and get to about 65ish sometimes before it hit "the wall" and lost all acceleration staying around 60ish.
2) On accelarating up a hill in most ratios it was quicker to get out and push and people on pushbikes where trying to pass.
3) On coming up to a roundabout lifting the accelerator slowing to 5-15mph then pulling away over the juction the engine bogs down and i'm left with a 40 ton rig bearing down on me with a driver whose not best pleased (probably cos hes had to disengage his cruse control for the first time in 200miles, but that another gripe)
Now ive had these symtoms, or should i say my wife has, as its her car, for about 12-18 months but as it was not my vehilcle i couldnt see the problem, although the relentless nagging does wear you down. I have had many attempts at trying to resolve, mainly by looking on forums and once actually discussing it with a highly trianed mechanic at the local LR dealers who informed me my hoses where collapsing and would have to strip them all off to check. However, on futher technical discutions with him i soon came to realise he had the mechanical aptitude of a gorilla and could not see him being able to hold a spanner, without it dragging on the ground, let alone use one. So it was down to me and although mechanically compedent (mechanical engineer by trade) i'm not a mechanic!
These are a list of things i had done before finding the solution.
a) Changed air filter
b) Changed fuel filter
c) Changed MAF sensor (always a favorite of the stealers)
d) Flushed out heavy oil & grease deposits in the inlet manifold)
e) Changed the engine vent-to-inlet filter
f) Checked connections & Pipework upteen times.
g) Checked all solenoid operations on vacuum & diesel lines
Alas none of the above gave me a blind bit of difference. However it did narrow it down. I had tried ingnoring it and putting it of put could only concluded it was a turbo problem.......I was right!!!
The reason for MY problem was a siezed variable actuating ring within the turbo itself. The actuator, which operates via a solanoid switch after a signal from the ecu using the systems vacuum to pull the linkage was found to operate fine, once linkage disconected, but was not able to move (vary) the variable nozzels on the tubo due to a build up of carbon deposits on the ring and nozzels themselves within the turbo. What had happened was the nozzels have seized in thier nearly maximum position. And thinking it through it actally made sense.
1) When accelerating through the gears everything is fine as the engine management changes the gear to suit load using information from all the sensors. However when in top gear the extra boost provided by the "open" nozzels has nowhere to go and thus activated the "overboost" sensor which inturn shut down the fuel supply from the high pressure pump to reduce the boost. However this only serves to reduce power until a happy equalibrum is acheived. This may be at different speeds depending on where the ring has stuck ie how much boost is provided.
2) As for pulling away from the roundabout & Accelarating up hill i can only assume its because the nozzels are in the max open position instead of closed position thus providing the incorrect flow of gasses over the turbine itself & consiquently giving it extreem "turbo lag" symptoms.
The turbo rectification once tubos removed was actually quite simple. Remove the housing where the ring and nozzels are throughly clean and rebuild checking operation of nozzels by pulling & pushing linkages. Very fine emery helps as does a airline to blow the particulate matter away.
The hardest part is the removal and installation of the turbo itself (this is not for the faint hearted) and require your arms to articulate in at least 17 places while working blinfold!!!! i kid you not its a pain. i did read on the above message that part of the gearbox was removed by someone to gain access. Belive me if had made things easier i would have gone down that road but cant quite see how its done. perhaps someone can advise.
Anyway that was
MY repeat
MY solution to this problem but i just wonder how many turbos have been changed by the LR dealers when a simple solution was available. I would suspect a smaller local garage would be a better solution as LR would be happy to change the turbo complete Im sure wheras the smaller garage with less overheads can probably afford the extra 2 hours it took to stip clean & rebuild from removal. My wife now loves me and thinks im wonderful and 4 months down the road its been running perfect and most of all it cost
NOTHING to fix apart from a weekend under the car.
So there it is and i can't see this being a isolated case as, i feel its a design flaw. And i certianly cant see LR coming clean but your welcome to thrust this infront of them when they tell you you requrie a new turbo for a zillion pounds.
Sorry to go on, and for the spelling mistakes, which a can't be bothered to check. Let me know if you want some pics of the stripped down turbo as i can't upload to this site (files too big).
Carl
This is the first time of sending a picture so if poor result apology's, however marked in green is the depression limiting valve,this has a filter on it and if blocked or not working properly can give [1] loss of power at higher speeds[2] oil gunge blow back in breather or dip stick,i always assumed these were fuel related problems ,but thanks to other diligent feed back by others has opened another thought,so just my opinion here,how many have had say other expensive parts fitted,to cure this problem,when just a new filter could cure it, i will try and get the part no, [ this is a 2ltr td4]. . .not sure if other engines have this. . .
