ACE challenge

I’ve had a 2000 Discovery 2 V8 ES since 2009 and generally have not had much trouble with it. I fitted an LPG system. I experienced and fixed the three amigos warning fault, plated the corroding rear chassis members, changed the rear air suspension cylinders and the front suspension turrets, front springs and shock absorbers – all the usual things. Two years ago I received an advisory about the ACE hydraulic pipes leaking and showing signs of corrosion. Last year the advisory was repeated and I received a verbal warning that I wouldn’t get away with it again. I want to keep the ACE. I’m aware of the difficulty of replacing the pipes like for like and decided to go down the route of exchanging them for two wire hydraulic hose. I removed the aluminium valve block from the pipes and chassis and dismantled it on the bench, removing the valves so that I was working with a bare aluminium block. Then I tapped the ports to fit ¼” bsp nipples, cleaned, reassembled and refitted to the chassis. Next, I had new hydraulic hoses manufactured with banjo fittings at the cylinder ends, 3/8” compression fitting to connect into the feed hose and return pipes at the bottom of the radiator and ¼” bsp connectors onto the valve block. I hope that all makes sense. I kept the original attenuator hose as it was in good condition.

I then filled the reservoir with fresh hydraulic fluid and turned the pump over by hand until fluid flowed from the output and then tightened the banjo bolt on the pump. Next, I “blipped” the ignition several times topping up the reservoir as the fluid was presumably pumped into the system. Thinking that all was well I started the engine and a few seconds later there was a pop and hydraulic fluid was squirted onto the fan and sprayed all over the front end of the engine compartment. The rubber hose of the attenuator had burst about 2” below the compression joint to the banjo bolt pipe and about 1” above the top constrictor on the hose.

I obtained a replacement attenuator hose and fitted it. I then made a test plug and lead that enabled me to test all three valves on the aluminium block by connecting them directly to the battery. The two valves on top gave a healthy clunk when operated. The valve on the rear edge was silent. I replaced it and tested again to confirm it was working. The new valve clunked satisfactorily.

So I refilled the reservoir, bled the pump and tried blipping the engine again. Between blips I rocked the body to try and energise the valves (without any signs that they were). This time I didn’t get to start the engine. After the third blip the hose burst in the same place.

If this has taken some time to explain it reflects the twelve months my Discovery has spent on axle stands on the drive. I managed to fall and tear a cartilage during the procedure and it took some time to get that repaired (more successfully touch wood).

So ….. has anyone any suggestions of any glaring errors I have made or suggestions of what to try next? I have been made an offer to take it away by a local Landrover fettler and at the moment I am sorely tempted to call it a day.

Thanks if you have made it this far.

Are you sure that you connected the outlet pipe(with atenuator) to the correct port in the block? cos if not there will be no circulation of fluid and the pressure builds up to dangerous level

sierrafery said:

Are you sure that you connected the outlet pipe(with atenuator) to the correct port in the block? cos if not there will be no circulation of fluid and the pressure builds up to dangerous level

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That's a reasonable question given my previous postings. I photographed and drew sketches of the assembly before I dismantled it. I checked and checked again as I reassembled it. I checked again after the two poppings. I'm sure it is correct.

Then it's possible to be a blockage in the valve block or something, remove te ACE relay and start it like that cos then it should be almost no pressure as the fluid should simply recirculate between the feed and return while the valves to the rams are closed

sierrafery said:

Then it's possible to be a blockage in the valve block or something, remove te ACE relay and start it like that cos then it should be almost no pressure as the fluid should simply recirculate between the feed and return while the valves to the rams are closed

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I'll give it a go. I'm going to quadruple check yet again that I have reconnected it correctly and then I'll gaffer tape the hose and put a hose clip over the rupture to prevent leakage - hopefully that will be adequate to hold it whilst there is no back pressure. Thanks for the advice - I'll get back to you once I've tried it.

With removed relay the ECU doesnt get feed and you should see te fluid circulating hard in the tank, if it blows the pipe that way it's ceratin that there's blockage in the block, can be the filter or the pressure control valve or something, the circuit with relay removed is like i edited with red, here's from the WSM:
ECU does not receive ignition ON signal. No ARC control = 'Locked bars' condition
...
'Locked bars' means that all pump flow is directed through the valve block and returns
to the reservoir. ...

There should be a P stamped on the valve block where the feed pipe goes, see this ACE pipe schematic

It is very easy to get them the wrong way round, just remember the ram ones are almost straight through, and the pump are a seperate pair.

I am not sure if it is front ram or pump pipes, they are very easy to accidentally swap over.

Attached drawing of the ACE pipe layout

It is the bottom pair which can get swapped, they sort of cross over between the inner wing and the block.

It never ceases to amaze me why people put themselves through this to keep a system, as good as it may be, when it’s working, that is very easily bypassed. A full year of stress and a vehicle off the road for nothing really

meego said:

It never ceases to amaze me why people put themselves through this to keep a system, as good as it may be, when it’s working, that is very easily bypassed. A full year of stress and a vehicle off the road for nothing really

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Ok, it's a system, that does work, sort of. But if you replace your shockers with good quality gas ones, it is almost unnecessary. Mine works as it should, but if you really push the beast through a series of bends, it reacts too slowly.
The one time it switched itself off and locked, it drove as well as without, more or less and I am talking about when I took it down our mountain road, a 10 minute drive with 44 bends, of which three are hairpins and which drops 360 metres. Same on the way back up.
It seemed to fix itself once I turned the engine off, checked all fuses, (which were all intact) then tried it again.
So if mine ever played up I would simply remove the fuse and let it just lock. And I don't think I'd ever fix it. Would rather spend the time and money on a good set of shocks.

Stanleysteamer said:

Mine works as it should, but if you really push the beast through a series of bends, it reacts too slowly.

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But do you really know how it should work ? for example that it's conceived only for road use at speeds above 25mph?... below that speed it's disabled

Stanleysteamer said:

Ok, it's a system, that does work, sort of. But if you replace your shockers with good quality gas ones, it is almost unnecessary. Mine works as it should, but if you really push the beast through a series of bends, it reacts too slowly.
The one time it switched itself off and locked, it drove as well as without, more or less and I am talking about when I took it down our mountain road, a 10 minute drive with 44 bends, of which three are hairpins and which drops 360 metres. Same on the way back up.
It seemed to fix itself once I turned the engine off, checked all fuses, (which were all intact) then tried it again.
So if mine ever played up I would simply remove the fuse and let it just lock. And I don't think I'd ever fix it. Would rather spend the time and money on a good set of shocks.

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sierrafery said:

But do you really know how it should work ? for example that it's conceived only for road use at speeds above 25mph?... below that speed it's disabled

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This car is a large heavy 4x4. For me it’s a very comfortable road car that I see no need to be throwing into corners. Each to their own, but if you are going so fast into bends with this vehicle that you “need” ACE, your driving skills need looking at. And by “you” I don’t mean any of you two guys quoted

meego said:

This car is a large heavy 4x4. For me it’s a very comfortable road car that I see no need to be throwing into corners. Each to their own, but if you are going so fast into bends with this vehicle that you “need” ACE, your driving skills need looking at. And by “you” I don’t mean any of you two guys quoted

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Quite!
If for some reason you, (i.e "one") wants it to handle like a rally car, , one puts much thicker anti roll bars on, one lowers it and uses stiffer springs, shocks and lower profile tyres, as one would on any car.
But why would any"one" do that? On a 4x4? Only for a poseur.

Stanleysteamer said:

Quite!
If for some reason you, (i.e "one") wants it to handle like a rally car, , one puts much thicker anti roll bars on, one lowers it and uses stiffer springs, shocks and lower profile tyres, as one would on any car.
But why would any"one" do that? On a 4x4? Only for a poseur.

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One will have to use “one” more often in one’s future posts I didn’t pay much attention in English

sierrafery said:

But do you really know how it should work ? for example that it's conceived only for road use at speeds above 25mph?... below that speed it's disabled

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Believe me, the trip down the mountain is at a lot higher speed than 25mph! Even the artics go faster! I can hear the pump working on each bend.
I can even hear it on roundabouts.
One day I may record the trip on my dash cam and put it up as I do seem to be mentioning it a lot, if I can do it without getting stuck behind a campervan!

meego said:

One will have to use “one” more often in one’s future posts I didn’t pay much attention in English

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Just like you, wishing to not give offence to any particular "you"!

meego said:

This car is a large heavy 4x4. For me it’s a very comfortable road car that I see no need to be throwing into corners. Each to their own, but if you are going so fast into bends with this vehicle that you “need” ACE, your driving skills need looking at. And by “you” I don’t mean any of you two guys quoted

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Active ARBs are much better for road use than no ARBs, so if I removed the system it would roll a LOT, as like when a drop link snapped and I pulled the relay.

I like the system as it works well, it stops roll, it make the car much more comfortable on a twisty road, it allows good articulation.

And I am supposed to have 1 car for everything or a seperate car for every task?

MJI said:

Active ARBs are much better for road use than no ARBs, so if I removed the system it would roll a LOT, as like when a drop link snapped and I pulled the relay.

I like the system as it works well, it stops roll, it make the car much more comfortable on a twisty road, it allows good articulation.

And I am supposed to have 1 car for everything or a seperate car for every task?

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I did say “each to their own”. I don’t expect you or anyone else to agree with my opinion though. I have had no issues with the system bypassed. You chose to alter and maintain it. It’s no big deal !!

MJI said:

Active ARBs are much better for road use than no ARBs, so if I removed the system it would roll a LOT, as like when a drop link snapped and I pulled the relay.

I like the system as it works well, it stops roll, it make the car much more comfortable on a twisty road, it allows good articulation.

And I am supposed to have 1 car for everything or a seperate car for every task?

Click to expand...

No ARBs would be lethal, pretty well. don't thing anyone actually suggested having none at all!
ACE was originally conceived to counteract the roll all highish vehicles have and it had been widely touted on TV that 4x4s were dangerous because of their so-called tendency to roll over.
Disco 1s never had it, and yes they rolled a bit. But that could be reduced quite a bit by putting gas shockers on. Mine are GAZ fitted in about 2004and they dramatically improved the drive on the road.
The D2 being a bit longer would have had even more roll if they didn't do something about it. Thicker roll bars would have done this but then, as it is supposed to be good, off road, this would have been a limiting factor, off road. Less articulation. So ACE is kind of best of both worlds cos it still allows good articulation as, as @sierrafery said, under 25 mph it don't work, which is fine for off road.

All ARBs have to be a happy medium as they are not easily altered without taking them off the car, or sliding joints along them, which requires tools etc. ACE itself cannot cope with extremes, but it has a wider range than fixed ornery ARBs.
You buy a car for a mix of jobs usually, hence estate cars, little town cars, etc etc. No one car can do everything.
But a Disco I feel is a fantastic mix of long distance, comfortable cruiser, load -lugger, and tow car. And one with 7 seats is also a people carrier. So, very versatile. But when we go to France we do still take our Citroen Pluriel as it is smaller, faster, more economical and a soft top, so it pushes different buttons. So no, one car can't do everything, but you don't need a car for each activity unless you are doing extreme activities.
Cheers!