blackwolf wrote:

Waka56 wrote:

... What does the actuator actually do? ...

The actuator, under ECM control, alters the angle of the static vanes in the turbine part of the turbo, and by so doing adjusts the speed of the rotor to alter the effective boost. By this means the boost pressure can be adjusted largely independent of engine speed and exhaust gas flow, with the particular result that high boost pressures can be obtained at low engine speeds. Similarly when power is not required, the boost pressure and hence fuel demand can be reduced.

In the 13 years I have owned my Defender I have had two problems relating to the turbo performance. The first was caused by the linkage in the turbo jamming in the "no boost" position, with the result that the actuator could not shift it. I can't remember the fault codes, but the effect was immediate and very significant, no boost, negligible power (made more alarming by the fact that I was just about to start the climb up Haldon Hill with a 3-ton trailer at the moment of failure). Disconnecting the link from the actuator and turbo and waggling the operating lever on the turbo sorted this out, and it hasn't recurred. Note that the vane operating lever should move so freely it feels as though it is broken and doing nothing. I think that fitting a catch can to the engine breather circuit and blanking the EGR probably both prolong the life of the turbo.

The second issue I had was caused by one of the sense wires in the harness from the actuator to the ECM chafing through on the engine, which resulted in the actuator immediately moving to the full boost position and staying there whenever the ignition was on. This has two interesting effects, firstly the engine power is impressive since full boost is present all the time, and secondly the induction noise (especially as I have a large-bore RAI) is extraordinary, like rolling thunder (reminded me of a Vulcan at full climb with afterburn)!

Thanks Black wolf  Making my Defender great again. (Or trying to at least xD)

LandRoverAnorak wrote:

For some time now, my Defender has been suffering from a strange intake-related noise, almost like that of a dump valve fitted to boy racer hot hatches, and occasional power delivery hiccups, which were explored in this thread a few weeks ago. I even took it to my local independent LR garage, who couldn't find anything wrong. Anyway, as a bit of a gamble I decided to replace the turbo actuator, which seemed to be a likely suspect for the problem and so far, so good!

The actuator is located on top of the turbo on the right hand side of the engine and is relatively easy to access. It's secured with three torx head countersunk bolts through the turbo casting and is connected to the acuating rod for the vanes with a small circlip. The latter has a slot in the end to make it easy to remove with a small flat bladed screwdriver. There is also a large multi-plug that needs to be disconnected by squeezing the tabs on each side.

The old one removed showing the connector to the actuating rod:


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The new one prior to installation. The original is a Hella part whilst this is obviously a pattern part, purchased from eBay. The significant number when finding a replacement is the 'G-72' stamped on the side, which also exists on the Hella unit under the dirt:


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With the original unit removed I was able to check that the linkage was free and also add a bit of lubrication for good measure:


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And the new unit bolted into place:


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The whole job only took about half an hour to do and was quite easy. The results were immediately obvious with much smoother power delivery in first and second gear and no odd noises from the air intake. A definite result!