The TDV8 in the L322 has surprisingly low oil pressure specs and I note that the oil pump part number has changed twice since the engine's appearance in the MY13 L405 which was the same as the L322. With the engine's willingness to work at very low revs, I'm wondering if oil pressure is adequate at those revs. I'm working towards installing a pressure gauge in my L322 to monitor its pressure lower in the rev range.

Can anyone provide the pressure specs from the last engines in the L405? I'm wondering if the oil pump was revised to provide a higher pressure.

From WSM 2018

The oil pump housing also contains a relief valve assembly which is secured in the housing with a roll pin. The oil
pump supplies a greater amount of oil than is normally required for adequate lubrication. The oil pressure relief valve
is incorporated in the pump oil circuit to limit maximum oil pressure to 4.5 bar (65.25 lbf/in²).
The pressure relief valve is a spring-loaded bypass valve which comprises a small piston and spring located in a bore
in the oil pump housing. Under normal pressure conditions, the spring holds the relief valve closed and all the oil from
the oil pump flows into the oil galleries and to the bearings. Under abnormally high oil pressure conditions (when the
oil is cold for example), the pressure relief valve opens. Oil pressure pushes the small piston back in its bore in the
housing by overcoming spring tension. This allows some of the pressurized oil to bypass the main oil galleries and
return back into the oil pan. Most of the oil still flows to the bearings and a preset oil pressure is maintained. 2018 SE SDV8 4.4 Byron Blue

Relief valve setting doesn't confirm the actual pressure but 65 psi is much higher than the 35 psi maximum pressure at 3000 rpm at oil temp 65 deg C of the L322's pump.

Do you have the 2018 pump pressure specs?

GraemeS
I have not seen anywhere what oil pressure range (specs) to expect depending on revs etc?
Oil pumps are usually a positive displacement pump and therefore the pump/system need's to be protected by a relief valve.
Hence they quote the pump can possibly hit more than 4.5bar with cold oil at start up, what it would be at normal temp at idle, only a pressure gauge as you point out, will help you.

Unfortunately the good old days of oil pressure gauges and dipsticks have gone

The low pressure switch should have been a pressure sensor then you could have seen it on GAP or CarScanner app.

On the Car Scanner app, I can see DPF diff pressure, Boost pressure, Fuel Rail pressure and Intake manifold pressure etc. But one of the most important -oil pressure is missed out.
But report back how you get on it would be interesting  2018 SE SDV8 4.4 Byron Blue

Just found this in WSM its in Diagnosis and Testing section of 303.0

C1: CHECK FOR LOW ENGINE OIL PRESSURE
1 Remove the oil pressure sensor.
2 Connect a suitable oil pressure gauge in place of the oil pressure
sensor.
3 Start the engine and check for leaks at the gauge connection.
4 Allow the engine to idle and monitor the oil pressure.
5 Raise the engine speed to 2,500 rpm and monitor the oil pressure.
Is the oil pressure less than 0.50 bar (7.25 psi) between idle and 2,500
rpm?
Yes
GO to C2.
No
GO to C3.
C2: CHECK FOR LOW ENGINE OIL PRESSURE AT ENGINE SPEEDS GREATER
THAN 2,500 RPM
1 Raise the engine speed to above 2,500 rpm and monitor the oil
pressure.
Is the oil pressure less than 1.0 bar (14.5 psi) at engine speeds greater
than 2,500 rpm?
Yes
Pressure this low may indicate a problem with: oil pump, filtering,
clearances within the engine. Check if there are any other indications of
engine faults (noise, etc), refer to the symptom chart above.
No
GO to C3.
C3: CHECK FOR HIGH ENGINE OIL PRESSURE
1 Monitor the engine oil pressure at varying engine speeds.
Does the oil pressure reach 4.0 bar (58 psi)?
Yes
Pressure this high may indicate a blockage in the lubrication system. If
this is not resolved, high oil pressure will lead to engine oil leaks and
other failures.
No
If the oil pressure stays in the band between 0.50 bar (7.25 psi) and 1.0
bar (14.5 psi) this would be considered normal. 2018 SE SDV8 4.4 Byron Blue

I found specs for the 2.7 and 3.0 TDV6 which also have a 65 psi relief setting yet only 27.5 psi at 3500 rpm. Your specs find reinforces my view that the pressure is too low for the work that the engine will do lower in the rev range still at MY18. My experience from engines in years gone by is that the relief valve is opening most of the time so that there is adequate pressure at lower revs, to the extent that the valve plunger needs to be replaced from time to time because the seat has worn. It seems with these engines that the pressure is never expected to get to the relief pressure unless there is a blockage and therefore pressure is basically linear with the revs. I was initially surprised that Ebay is full of adverts for bearing sets for these engines but now suspect that many are being replaced even though there's little or no mention of this on this forum. I've been accustomed to pulling my 2.5T caravan at 100 kph in top gear but won't be doing that again, probably simply achieved by using sport mode.

Today I purchased a pressure gauge and adapter to monitor the pressure to determine at what revs the pressure gets high enough for my liking. If I find that I want permanently to see the pressure then I'll make my own small 2-digit display to sit in the bottom right of the instrument cluster using the pressure transducer supplied with this gauge.

How did you get on with this Graeme?

Once warm, idle pressure was around 12 psi, 1300 rpm (100 kph in 8th) around 15 psi and maximum a little over 35 psi with 5W-30 Magnatec A5 that had done 10K kms and due for a change. New 5W-30 made no difference so Edge A3/B4 5W40 was tried which made very little difference, now with around 18 psi at 1300 rpm.

A new pump fitted over the last 3 days made no difference whatsoever to the hot pressures. By the time the coolant temperature gauge gets to its steady warmed-up position and with oil temperature around 85 degC, the pressures have plummeted. On this afternoon's short test drive both the oil and coolant temperatures stabilised at 88 degC.

I don't know if the low hot pressures are normal as oil pressure isn't usually checked by mechanics.

I am no expert , but I think some thoughts should be given to the effects of higher oil pressure on the already very vulnerable rubber O ring seals on the turbo feed pipe, and indeed on the oil cooler body.
Given that they are known for leaking as they age and get brittle, higher oil pressure can only make the leaks worse, and I-dread to think of a sudden failure of them at speed.
Just my thoughts, ?.
Mike. G reg 2.5VM Vogue Portofino red 1991- 1999
V reg 2.5td P38 Rioja red 1999- 2006
53 reg td6 Vogue Oslo blue 2006- 2015
11 reg 4.4 TdV8 Vogue SE. Baltic blue 2015- date.
https://www.fullfatrr.com/forum/topic56162...tty+affair

Absolutely.

There seems to be a fad around worrying about oil pressure suddenly … and that there is hand wringing around it working at low revs and that somehow it must be bad design and we are doomed.

To me, pressure cant be everything … flow rate surely must matter too ? Perhaps the tdv8 has high flow rates which counter the lower pressure so that overall oil delivery rate is the same. Larger bore channels less likely to block for off road use and crappy working environments ? It’s well documented that LR will modify existing blocks to accommodate the working range of angles and environments.

Let be honest, it’s rare to see the tdv8 let go with its bearing shells compared to the tdv6, so not overly worried. V8 or else ...

Whilst many TDV8/SDV8 engines have ended-up with failed big-end bearings, I can only assume that because my engine's pressures meets specs that nothing untowards had happened to my engine. I will in future tow in Sport mode and will stop upshifting just because the engine will pull acceptably in a higher gear so that the pressure is a little higher along with a little less momentary load on the bearings due to the crankshaft spinning slightly faster as something that I can do to try to extend the life of this engine.

Yeah, I think thats a fair point with holding gears. To an extent, it should already do that when towing anyway should it not ? The gearboxes should self - sense towing and select its towing sub-mode, which in turn will hold gears longer etc etc . V8 or else ...

My biggest concern is that I've unknowingly upshifted to 8th cruising with the van attached the moment the engine was happy to stay there, but now informed I'll be able to look after the engine better.
Of interest, a LC200 owner has stated that his vehicle's hot oil pressure as indicated by the standard pressure gauge at 100 kph and 1450 rpm is only slightly above hot idle pressure, so not too different to my TDV8. I guess it's the philosophy with modern engines where the designers do their utmost to reduce engine friction for reduced emissions.