Hi guys,

Just wondered if anyone had some advise for me on my 2007 v6..
Basically ive replaced the valve block, filter, pressure switch, solenoids and put new fluid in the system but when driving along slowly the front end makes a loud knocking/clunking sound and as soon as I turn a corner the red suspension light comes on. Read the fault codes and it gives me C1B11 (pressure control valve) and C1119 (hydraulic pressure). If I drive faster and keep the revs up and turn left to right the suspension light doesn't come on until I slow down. But once the red fault light has come on and locks off the bars the clunking noise seems to stop. My next option is do I replace the pump or the front stabilizer bar? I've inspected the front bar and there seems to be no leaks present and the fluid in the reservoir seems to look like it's being pumped round if that makes sense..

Any help would be gladly appreciated!

Thanks[/i]

Before you go to the expense of a new front ARC bar and pump, try changing the fluid reservoir. Inside the reservoir is a gauze mesh filter to protect the pump, if this is sludged up and restricted the pump will cavitate and lose ability to supply fluid under pressure to the system.
It is possible that with the pump turning at a higher speed, it is able to pull enough fluid through this gauze to satisfy the system but at lower speeds, it becomes starved.

Thanks for your reply, I have already removed the reservoir and cleaned it out as the gauze was dirty.. it looks pretty clean to me now so probably not worth changing?

Sounds like the pump isn't putting out enough pressure. Try putting the car into low range and see if it does it then, you will be able to hold the revs higher without going fast.

The pump is around £1k...

Before you drive it in Low Ratio make sure that you are NOT on a metalled road, find a grassy / sandy area or loose gravelly area otherwise you can damage the transmission with wind up, driving on a lower friction surface will allow the wheels to spin out any wind up that may build up in the system. 2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
2018 Melting Silver Mini Countryman PHEV - soon to be replaced
2015MY Corris Grey SDv6 HSE Dynamic, the best car I have ever owned, totally reliable only a cou0le of rattles in 3 years, now no longer in my care
Also in my garage is a 1996 TDi300 Defender 90 County HT made into a fake CSW

How is driving in low ratio any different to normal ?

The cars are full time 4wd, with 3 diff's balancing the torque etc. so long as no special programs are selected then only difference between high and low range is the gear ratio in the transfer box.

Is no one thinking it's the front stabilizer bar that's causing the issue? I only say this as it really knocks and bangs when you drive the car until the fault light comes on..

The fault codes suggest that it's the pump not giving enough pressure or that one of the valves isn't working as it should be.

It may be that your bushes are well and truly destroyed and allowing the bar to move so much that it's crimping one of the feed hoses (unlikely) or being as you've replaced the valve block it could be that there is a short to earth somewhere but that would usually throw random intermittent errors rather than just when cornering. The fact that the warning light comes on when you slow down says to me that it could be the pump as the flow rate is based on engine speed (hence try low box and keep the revs up to test)

The banging could be either the sway bar, the lower arms or the drop links. Most likely is the sway bar bushes.

There is a software update to stop the ACE system from being quite so agressive, it would be a good idea to check you've got it. But if the banging is as bad as you say then I would resolve that first before going further.

The pump's output rate is at maximum by 1000rpm so no need to be in low range. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

Thats is true if the pump is working correctly, but if the relief valves have gone weak the pump won't be able to maintain a high enough oil pressure, so reving the engine over 1k rpm will allow the pump to reach the required flow rate/pressure.

Well I've managed to find a new pump on eBay for £200, has anyone changed the pump before? Big job?

I would test first and confirm its faulty before pulling the trigger on a new pump, I wouldn't want you to spend £200 if it's not the pump at fault.

I'm not sure what it's like to do on the v6, but on the v8 it's not a massive job. Maybe 1.5 hours to remove and replace.

I've tried driving the car in low range with the revs high and fault light doesn't come on, which seems to me what everyone is saying is the pump isn't producing enough pressure. I've had the lower arms, bushes and wishbones replaced last year and all has been fine until recently. I just can't explain the knocking/clunking noise that occurs when turning and driving at low speeds before the fault light kicks in..

could you get the wife to drive the car and you record it ?

did this get resolved i've got the same symptoms and codes on mine