I understand flow / pressure arguments... But, we're attempting to lubricate a rotating piece of machinery and overcome centrifugal forces and force (not dribble) oil onto highly stressed bearing surfaces.

My understanding is that you need sufficient oil pressure to force oil through all the small oil galleries, especially those feeding the crank's main and con-rod journals (not to mention the piston cooling / little end lubrication jets, and of course up to the cams and everywhere else that's pressure fed, rather than splash lubricated).

It also has to be delivered to the crank with sufficient pressure to overcome centrifugal forces generated from the rotation of the crank itself. Ensuring oil makes it not only onto the surface of the main bearings in sufficient quantity, but also delivered to the big ends and not defeated by rotational forces.

I can only think that oil is being delivered at such low pressure to reduce the parasitic losses from running the oil pump at higher pressures, all in the name of emissions / economy targets.

Has anyone got the specs to hand for oil pressure vs engine RPM for the 4.4 TDV8? I wonder if it's been reduced on the later car's to improve fuel efficiency?

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)

Danb_220_2019 wrote:

Indeed, as above.

As long as the pressures are in spec, then I wouldn't worry. It may be that the lubrication system is set up for 10L/min flow at 12PSI where the oil pressure sensor is located - a good flow at low pressure there may mean a lower flow rate at higher pressure elsewhere in the oil system and vice versa.

Would you rather your bath filled at 100PSI and 1L/min or 1PSI and 100L/min?

The write-up in the WSM refers to adequate pressure.
Note that the same pump is used on the 3.6 which has the same crankshaft bearings but which produces less torque.

The oil pump bypass opens at 4.5 bar.
The spec at 3500 rpm is 2.4 bar (2.0 bar min)
IOW when the oil is warm the pump is never in bypass, all oil goes through the engine.
One can draw a line from 800rpm idle / 0.8 bar to 3500 rpm / 2.4 bar to get a rough idea - minus some flow loss - what the pressure / rpm is.
1400rpm = 1.25bar roughly.

But that's just bar, not volume.
There is no spec in the manual showing the amount of oil the pump is supposed to pump at a given rpm.

The oil pump has to deliver the oil to where it's needed.
Journal bearings create their own oil pressure by rotating and that's much higher than what the oil pump delivers.
The inlet for journal bearings is at the low pressure side, of course, they may even suck the oil in a little.
Remember those little oil reservoirs on steam engines?
A 'drop of oil a second' was enough.

The HTHS (HighTempHighShear)value of engine oil gets into play when it needs to keep parts apart under load.
The 4.4 TDV8 oil spec is SAE 5W-30 & Ford WSS-M2C934-B.
Most oil meeting that spec also meet ACEA C1 spec, low SAPS, stay-in-grade, and those oils STILL need to have a HTHS value of at least 2.9mPa.s
The HTHS is measured at 150C, btw.
The stay-in-grade part is about the viscosity at 100c (the 30) during the whole oil change interval.
HTHS is linked to this but it depends mainly on base oil quality.
Modern group III base oils are not true synthetic oils like group IV and V but still pretty good and used a lot for the 5W-30 C1 oils.

Without UOA's showing the actual dilution it's anyone's guess if the dilution is a problem in your engine.
Using a quality C1 5W-30 gives piece of mind during your oil change interval. 2012 4.4TDV8
2000 Honda S2000

There is a thread on this forum….how many miles on your FFRR. There are plenty of examples with >100k miles

Engine failure on the L322 4.4 is beyond rare
I have heard stories about engine runaway (take with pinch of salt) on the 4.4s that haven’t had the engine / turbo oil drain mod. None of the old wives runaway stories have persuaded me to have the mod. An occasional Italian tune up helps IMHO. Some folk drive the FFRRs without use of the 2nd turbo…and in truth the engine has so much torque, you can drive like this. But this engine flies over 3000rpm and makes a lovely noise ..

When my MY 11.5 4.4 TDV8 goes to a breaker’s yard, I would be really surprised if the reason is engine related. As far as i am concerned, at 116k miles, the big old lump is just about run in

Rambles wrote:

<SNIP> Engine failure on the L322 4.4 is beyond rare <SNIP>

I think it would be difficult to find any forum on cars where engines have a 100% non fail record.
Your points are valid apart from the one about the 8speed as it will not 'labour ' under load and changes down quick enough when under load. One of my issues with it is that fact that on my L322 it is all too happy to change down and use the revs which seem excessive for the load. Maybe the L405 is different? 2012 TDV8 Vogue (L322)

D3Jon

Looks like those are L405 SDV8 engine failures rather than L322 TDV8 engine failures…

Rambles wrote:

Looks like those are L405 SDV8 engine failures rather than L322 TDV8 engine failures…

Ooh, very good observation! All but one are SDV8's. I never picked up on that, so obvious when you stand back a little!

I was grouping them together as a TD/SDV8 as to me, they're the same engine. Perhaps not though, or it's something in the packaging of the engine in the L405!

If it is internal to the engine, what's changed with the SDV8 I wonder (EDIT -> other than the slight power hike and turbo drain mod)? An even lower pressure oil pump to meet emission targets?

This is exactly why I started this thread!

J 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)

It would be easy enough to compare the oil pressure tests in the respective workshop manuals. Same engine internals will respond differently in terms of stress and wear to different ECU gearbox and engine mapping. Like I said I 'think' my L322 revs too high under load for the torque capability of the engine at low revs but this may be entirely appropriate for reducing undue bearing load at low rpm/ low oil flow rates? Additionally we know the ECU holds higher revs during warm-up to speed up engine temp rise but this has always puzzled me as it's load not revs that creates internal engine heat so maybe safe oilflow to the bearings is the real reason? I can however imagine customer feedback or marketing to want the lowest possible revs for any gear to emphasis the effortless quiet quality of the power unit. 2012 TDV8 Vogue (L322)

D3Jon

I think you’re right - there is no difference internally between the two
Same max torgue….power up by approx 20bhp…emissions down
Maybe different tuning means the SDV8 runs hotter ? Not that this would necessarily make any difference to engine wear
Do the SDV8s suffer more from oil dilution from DPF regens than the TDV8s?

20bhp at high revs is easy to acheive through mapping and is insignificant as a load on the engine. I doubt it runs hotter to lower emissions as the purpose of the EGR system is to reduce combustion temperatures to reduce NOX emissions. The emissions reduction of NOX on the Euro 6 version of the SDV8 is done by the adblue injection in the exhaust system. Difficult to imagine after so many years of use and develpment that they messed up the DPF regen strategy and worsened oil dilution but at the same time marketing may well have been pushing for longer service intervals as a selling point. 2012 TDV8 Vogue (L322)

The latest oil pump part number fitted to my L322 did not change oil pressure at all, so no change in pressure menas no change in capacity. I noted that the rotor widths were the same.

If only the engine manufacturers added an extra injector into the exhaust manifold / downpipe (post cylinder head & pre DPF) and injected the extra fuel THERE for DPF regen purposes, we wouldn't have all this oil dilution mess!

All the extra fuel would be added post cylinder, so couldn't get past the rings and into the sump. Mind you, that'd be extra cost (injector(s) & plumbing), rather than just a software change.

Am, I missing something here? Or is the extra diesel actually combusting as it passes through the exhaust valves and into the manifold? Can't be though, surely? That'd burn out the exhaust valves.

I really should Google this up, but thought I'd ask here in case anyone's ever read up on this.

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)

GraemeS wrote:

The latest oil pump part number fitted to my L322 did not change oil pressure at all, so no change in pressure menas no change in capacity. I noted that the rotor widths were the same.

That's interesting Graeme, so no updated parts like there is for the TDV6, would surely mean there's no problem with the oil pump on the TDV8! Which has to be good news!

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)