I didn't find anything definitive during the rebuild and looked at everything. I bought the car at 90k miles and although it had MD service history I've no idea how it was treated. I was having dpf regens every 150 or so miles even on Motorway runs, hence 6-7 weekly oil changes (I do lots of miles). Last summer I eventually traced the premature regens to a failed dpf (tell tale sooty exhaust tips) that was replaced and regens are now great, drove down to the French Alps last Saturday and it did 750 miles before a regen. All seems good now, but would feel happier if I could fine a definitive reason for failure. L405 SV Autobiography LWB SDV8, finished in Aston Martin China Grey by ETO division.

Not disputing that oil dilution is likely contributing to bearing failure, after monitoring oil pressures and seeing oil pressures prior to the oil getting up to the temperature at least double that of when the oil is warm, I suspect cold starts are playing their part in causing accelerated wear due to inadequate lubrication especially if combined with other than gentle driving until warm. Even at 20 degC overnight here ATM, initial idle pressure is 35 psi but only 12 psi once up to temperature and initially over 50 psi at 1200 rpm but only 15-16 psi once warm. My suspicion is that there could initially be inadequate bearing lubrication due to insufficient oil until the oil is at its hot viscocity where it flows much more readily, as allowed for by the engine designers.

My rural abode allows gentle warm-up driving until oil pressure has subsided to its hot pressures, which it currently does after around 10 minutes and around the time the coolant temperature gauge shows normal.

4RRS wrote:

I didn't find anything definitive during the rebuild and looked at everything. I bought the car at 90k miles and although it had MD service history I've no idea how it was treated. I was having dpf regens every 150 or so miles even on Motorway runs, hence 6-7 weekly oil changes (I do lots of miles). Last summer I eventually traced the premature regens to a failed dpf (tell tale sooty exhaust tips) that was replaced and regens are now great, drove down to the French Alps last Saturday and it did 750 miles before a regen. All seems good now, but would feel happier if I could fine a definitive reason for failure.

I rather sadly watch my Gap IID tool like a hawk. Having an Android 12" head unit helps as I run the IID app on that to save being distracted looking at my phone based app. L405 SV Autobiography LWB SDV8, finished in Aston Martin China Grey by ETO division.

GraemeS wrote:

Not disputing that oil dilution is likely contributing to bearing failure, after monitoring oil pressures and seeing oil pressures prior to the oil getting up to the temperature at least double that of when the oil is warm, I suspect cold starts are playing their part in causing accelerated wear due to inadequate lubrication especially if combined with other than gentle driving until warm. Even at 20 degC overnight here ATM, initial idle pressure is 35 psi but only 12 psi once up to temperature and initially over 50 psi at 1200 rpm but only 15-16 psi once warm. My suspicion is that there could initially be inadequate bearing lubrication due to insufficient oil until the oil is at its hot viscocity where it flows much more readily, as allowed for by the engine designers.

My rural abode allows gentle warm-up driving until oil pressure has subsided to its hot pressures, which it currently does after around 10 minutes and around the time the coolant temperature gauge shows normal.

That's a big discrepancy in warm-up time when they're both circulating in the same block.

Yes but the coolant is also being heated by the FBH in winter and thus coolant temp is not the engine temp. Oil temperature is the crucial measure of when an engine is up to 'operating temps' and thus able to safley be run under load. 2012 TDV8 Vogue (L322)

OK, heat from a source other than the combustion chamber and the sump could be providing extra cooling too.

According to WSM specs, once the oil gets to 65 degC it's up to temperature as it's viscocity has lowered such that idle and maximum pressure match specs.

If 65deg C is 'operating temps' then the lag is much less. 2012 TDV8 Vogue (L322)

How many people that talk about fuel dilution can show used oil analysis reports (UOA's) showing the actual measured fuel dilution?

Reading this post one can reach the conclusion people using the ECU 'Service required" notification as their oil change interval are ruining their TDV8.

Maybe, just maybe, having your DPF cleaned every now and then isn't so bad.
Maybe, just maybe, it's part of routine maintenance on engines with a DPF. 2012 4.4TDV8
2000 Honda S2000

I'll check mine's 65degC pressures when I remember to connect the IIDtool on a morning run to get the mail.

GraemeS wrote:

Not disputing that oil dilution is likely contributing to bearing failure, after monitoring oil pressures and seeing oil pressures prior to the oil getting up to the temperature at least double that of when the oil is warm, I suspect cold starts are playing their part in causing accelerated wear due to inadequate lubrication especially if combined with other than gentle driving until warm. Even at 20 degC overnight here ATM, initial idle pressure is 35 psi but only 12 psi once up to temperature and initially over 50 psi at 1200 rpm but only 15-16 psi once warm. My suspicion is that there could initially be inadequate bearing lubrication due to insufficient oil until the oil is at its hot viscocity where it flows much more readily, as allowed for by the engine designers.

My rural abode allows gentle warm-up driving until oil pressure has subsided to its hot pressures, which it currently does after around 10 minutes and around the time the coolant temperature gauge shows normal.

Hi Graeme,

Those warm oil pressure readings seem low? I don't know what the actual spec is for a 4.4 TDV8 so could be talking out of my posterior, but 15-16psi at 1200rpm, seems very low to me?

With the ZF 8 speed box, 70mph on a motorway is achieved at little more than 1400rpm, I can't see the oil pressure rising much higher with just another couple of hundred rpm or so? If I had a traditional oil pressure gauge marked from 0-100psi (which they often are), I'd be very worried if the oil pressure was under 20psi at motorway speeds!

I know that general opinion with the Disco boys is that spun bearings / snapped cranks in the SD/TDV6 engine are highly likely to be a result of low oil pressure due to oil pump wear. Additionally, the V6 crank design, journal count and big end lubrication is totally compromised as PSA wanted a 'shorter' engine that could also be mounted transversely in a car. Their thoughts are that the SD/TDV6 being coupled to the ZF 8 speed box, giving low cruising RPM, together with a worn oil pump is one of the primary causes of spun bearings. And because the crank in the V6 oil burner is a bad design (AKA made of chocolate), it can snap when a bearing seizes.

I know they're completely different engines, with the TDV8 coming from Ford, but I wonder if low oil pressures linked to low cruising rpm's and perhaps also a worn oil pump isn't also a factor with TDV8 engine failures? Perhaps a car with 'mainly motorway miles' isn't such a good thing after all! 1992 RR Classic 3.9 efi Vogue
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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)

I very recently replaced mine's pump when I saw such low pressures after seeing quite high pressures at start-up in our late summer temperatures when I took the opportunity to fit a pressure sender while replacing a leaking radiator, done because of the unexplained bearing failures in the TD/SDV8. However the new genuine pump didn't produce any more pressure than the original that had done 180K kms. Hot specs are idle 12 psi (min 9) and 35 psi at 3000 rpm (min 29 psi) at 65 degC, which mine has achieved at its hot temps of 85-88 degC each time I've checked it.

I certainly don't like such low pressure at cruising speeds - 1300 rpm at 100 kph with my 31" tyres only showing 15/16 psi. I now ensure that 7th at 1600 rpm is used on hills where the pressure increases to 17/18, which while not much higher, the few extra revs are obvioulsly increasing flow because the pressure rises. My old habit of upshifting as soon as the higher gear pulls well enough has been abandoned to ensure higher revs when the gbox eventually upshifts.

I used to tow my 2.5T caravan at 100 kph in 8th, which I will now not allow by using Sport mode.

I've read that the D300/D350 has ecu-managed oil pressure, presumably an improvement from fixed flow.

Edit: One of my sons has my old 3.0 D4 now done well over 300K kms which should have an oil pressure gauge fitted within the next few days. The 3.0 TDV6 max pressure spec is 38 psi at 3500 rpm so we'll soon know if it still has acceptable pressure.

Oil pressure is just a measure of resistance to flow hence why it changes with viscosity and temperature. It's only low if it's below the manufacturers spec at a particular temp and RPM. Seemingly low pressure can actualy mean good flow and vice versa 2012 TDV8 Vogue (L322)

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? 2012 (L322) 4.4TDV8 Vogue SE, RSE, Fuji White over Arabica.
Previous V8s: BMW 645Ci, P38 4.6, P38 4.0, Merc CL500
Previous others: Honda x1, Volvo x7, Rover x6, BMW x6, Ford x1, Mercedes x2, Skoda x3, VW x2, Renault x2, Citroen x1, Mazda x3, Nissan x1, Audi x3, Kia x1, Fiat x4, Subaru x3, Austin x2, Triumph x2, Jeep x2, Hyundai x2, Lexus x1, Mitsubishi x1, Saab x2... and some others I've forgotten!