[Engine] Oil Pressure Light & Clattery Noises after flat battery.

[smutts]

1.6 hdi 16v
Been a funny one.
Car started fine, then after a second, cut out. 
Tried to restart, but the battery was now dead.
Used multimeter to confirm battery death, no problems with engine earths, terminals etc.
Fitted new battery.
Starts fine, alternator charging fine, 
but now the oil light is now on, 
and the engine sounds horrible & clattery, like there is no oil.

How can a flat battery magically destroy the engines lubricating system?

Hoping the low voltage has messed up the engine & BSI settings, ie wrongly lighting the oil light.
can the injector settings get screwed up by low voltages and cause injector knock?

Any good ideas?

[SinsBird]

I wouldn't ignore the light and wouldn't start the car without verifying that the oil pressure is sufficient. Might be the valve lifters clattering cause of no oil pressure.

[smutts]

I'm thinking that the oil pump grenaded itself.
Fun day tomorrow trying to see what's going on.

[OMG]

Nothing on the diag?Be hell of a coincidence that the oil pump went at the same time.

[smutts]

Well here are my thoughts.

The oil pump is wrapped around the nose of the crankshaft.
I think that the rotor of the oil pump broke up on starting and dragged the engine to a stop.
Or the chaos of the pump eating itself knocked the crank sensor out of limits, which would cause the engine management to shut it down.
Also a weak cold battery trying to drag the crank through the wreckage might seem like a "dying battery"

Enter new battery, drags the crank through wreckage until the chunks rearrange themselves, allows the crank sensor bracket to get close enough to give the "right" signal and engine fires up.

And, sounds like a suit of armour falling down a staircase.

So the search begins for another DV6 engine.

Ford..................
HHDA
HHDB
HHJD
HHJC
HHJE
GPDA

Fiat.................
9HU

Peugeot & Citroen............
DV6ATED4: 9HX, 9HV

Mini.............
DV6ATED4: 9HZ

Mazda..................
Y406
Y646

Suzuki.................
9HX

Volvo..................
D4164T

Where have all the scrapyards gone?
Turned to "affordable" housing, every one.

[smutts]

Peugeot planet tomorrow, just to see if there were intermittent crank sensor errors.

[cancunia]

An easy oil pressure check is to loosen the turbo oil feed pipe. If you try that, wedge a screwdriver or similar at the side of the oil pipe banjo to stop the banjo moving when you undo & redo the banjo bolt.
Another car to add to your list is the Volvo C30.

[smutts]

Another car to add to your list is the Volvo C30.

Oops! Good spot, I forgot to post that one......

Volvo.........D4164T

[smutts]

The moral of the story is to not assume that the car is crying "Wolf" every time the dashboard habitually lights up like a Christmas tree.
My Bad. 

[smutts]

Finally got Peugeot planet going, no major engine fault codes, but all the doom laden ones are in the BSI fault codes,
Oil pressure low permanent fault & crank speed faults.
That tallys with my theory of lunching oil pump rotors distorting the crank sensor mount, which caused the original cutting out.
Just to add to the fun, the stupid plastic dipstick has snapped off.
But looking at pictures of the engine sump, it looks as though the dipstick passes through the oil pick up assembly.
Carnage there would probably trap it.

Youtube video with brick on the throttle until it disassembles itself?