Replaced the previously mentioned hoses this morning and... absolutely no difference

I'm sick and tired of this now, what else could it be?

no idea RR 2005 4.4 petrol
Any spelling mistakes are the fault of spellchecker
Previous MG J2, CITROEN light 15 x 2 gone unfortunately
Present MERC 180e, RANGE ROVER L322, JAGUAR XJS, MERC 280SE, MG F, JAGUAR S-Type 6v 2003, jaguar s-type 8v 2004, Ford Cougar

I have re-read the thread and I don't think there is anything left. If it can't be tolerated then it is time to sell the car.

Very frustrating and annoying though! 2012 Vogue TDV8 in Aintree green over sand

I can't give up Toby, it's either a mechanical or electrical problem which should be fixable.

I will just have to keep trying until I figure it out.

I've been thinking about the pump again, is it possible for the pump to generate the correct pressure but not be delivering the correct volume of fluid?

I understand the tdv8 uses a variable displacement pump but not sure if this type of pump has a flow control valve or not.

I have already replaced the pump twice though.

Once with an aftermarket unit which made no difference to the symptoms but whined terribly and the second time with a supposedly known good used pump.

i like that, positive RR 2005 4.4 petrol
Any spelling mistakes are the fault of spellchecker
Previous MG J2, CITROEN light 15 x 2 gone unfortunately
Present MERC 180e, RANGE ROVER L322, JAGUAR XJS, MERC 280SE, MG F, JAGUAR S-Type 6v 2003, jaguar s-type 8v 2004, Ford Cougar

I've just quickly read through this thread, it's not one I've been following.

Only seen one mention of the lower steering column (might be more... so apologies in advance, but I just quickly read through all 13 pages!)

Did you check the lower steering column UJ? It could be damaged or partially seized. Common issue on the Disco 3/4 which leads to noticeable heavy steering.

Jon 1992 RR Classic 3.9 efi Vogue
2014 Disco 4 HSE
===================
Both my fatties now gone...
Previous: 2011 L322 4.4 TDV8 Vogue SE /// 2002 L322 4.4 V8 HSE /// 2009 Discovery 3 2.7 TDV6 XS /// 2004 Defender 90 TD5 /// 1993 110 V8 Snatch Landrover /// 2005 Discovery 3 2.7 TDV6 SE (Aus) /// 1990 110 Isuzu 3.9 County (Aus) /// 1976 Series III Trayback (Aus)

Hi D3Jon, thanks for your reply.

Yes I've removed the lower column in its entirety and checked both UJs and the telescoping part.

They are free but I lubricated them anyway before reinstalling

Is the BCM/CEM the latest part number? YWC000923 if yours is a 6A chassis number. Just a thought but I know you have 7V from it to the sensotronic thing. 2012 Vogue TDV8 in Aintree green over sand

Its got a YWC500521 Toby.

This is a replacement for the original which was also YWC500521. Replacement made no difference, neither did a replacement valve.

I've got 7v and 840ma out of the BCM at idle which I believe to be correct.

OK, so that's for a 7A chassis and then that was superseded to the 8A chassis, part number YWC500810.

So you have a 2007MY and your OP mentioned 2006. It does not probably matter as you say, you have the correct voltage at idle.

It was just a thought. 2012 Vogue TDV8 in Aintree green over sand

Thanks Toby, that's interesting to know.

Yes the car is a UK 56 plate, 2006 registered but 2007MY.

Struggling to come up with any other ideas.

I really don't want to get into replacing the steering rack itself yet as I can't see that it would tighten up overtime only become more worn and loose?

I dont think it has internal leakage either as this should have shown up when doing my lock to lock pressure tests. (I.e I would have seen lower pressures compared to the pressure recorded when deadheading the pump)

If someone could confirm this train of thought that would be helpful.

It seems to be electrically OK and the pressure tests are all OK. The rack is the only part not replaced IIRC.

I assume a new or reconditioned rack is not cheap? 2012 Vogue TDV8 in Aintree green over sand

Yea that's right the rack is pretty much the only thing I haven't replaced at this point.

New will be crazily priced, refurbished not sure.

It's a big job for me to undertake on the driveway as the subframe has to be lowered.

I'm not sure if it's the problem though as I don't think it's likely for it to be mechanically seized and nothing in my pressure tests suggested it was bypassing fluid internally.

Just more thoughts...

Isn't the pump suppost to regulate flow so that it is the same at all engine rpms?

I've taken a video of the fluid inside the reservoir, please tell me if I'm seeing things but it looks like the fluid becomes more turbulent when the engine is revved and held at 3000rpm. (Steering wheel not being touched so no load on the system)

https://youtube.com/shorts/U8bn9yAl9bg?si=UjiUR7_4bnacStEe

YWC500521.
is that the correct one ??
if it is i would be try changing it, i know you have already done that, but i would try an other one RR 2005 4.4 petrol
Any spelling mistakes are the fault of spellchecker
Previous MG J2, CITROEN light 15 x 2 gone unfortunately
Present MERC 180e, RANGE ROVER L322, JAGUAR XJS, MERC 280SE, MG F, JAGUAR S-Type 6v 2003, jaguar s-type 8v 2004, Ford Cougar