CitroJim wrote: 28 Dec 2022, 04:23
That's so frustrating Matt
Feeling your pain there...
Might be well worth a new starter and a full check of the integrity of connections and wiring to it... Especially as when the starter is not in the equation all seems good...
Think is a speed of turning over issue.
Some diesels are really fussy of their cranking speed and if yours was both slow and taking excess current causing a voltage sag to the electronics then that might account for it... Low volts into the engine ECU might make it just unhappy enough to cause the cough.. die...
One last test might be to jump using a very large, well-charged battery in parallel with the car's own and seeing if that makes any difference...
At risk of going over old ground and egg-sucking... You are certain the battery and its connections and heavy earth to the engine is good?
Fingers crossed the true root cause soon makes itself known
Happy to go over old ground more than once if we unearth the issue!
Quick summary of the old ground:
Starter has been apart and slight clean up commutator, regressed. Brushes not new but not down to nothing. Not touched solenoid and wondered if possible high resistance to it's contacts internally is a potential loss of motive force?
Starter, gearbox earth point and battery terminals connections all off, tickled with wet and dry and reinstated. All seem ok. Crude test with multimeter whilst cranking didn't seem to show significant volt drop during cranking (realise that I could have probed the solenoid output terminal to see volt drop between battery +ve and that point - pretty sure I did solenoid input instead as that's the more accessible connection from memory.
Lots of fuel system messing about which I am unconvinced now was fixing anything. Tiny bit of diesel bug found in fuel pickup strainer but nothing else untoward anywhere else in system. Fuel filter new. Previous one cut open and no bad news inside.
Intake manifold valve (anti shudder valve) is open when needs to be.
Timing checked and is correct. Runs well, well, when runs!
Glow plug fault, not tested plugs but started ok even in sub zero temperature a couple of weeks back.
Sure is other stuff might have missed.
We will get there, between us all 
