This engine will run with the oil filler cap off (and tons of gas with some entrained oil coming out of the oil fill hole). With the cap on it will start and run for a few seconds before the RPM drops gradually and it quietly stops running. The seems a carbon copy of this post https://forums.tdiclub.com/index.php?threads/blow-by-kills-motor-unless-oil-cap-off.462864/ - but there is no conclusion to the thread :-(
History: Car is Seat Alhambra 2011 2.0 TDI engine code CCF with 170k on clock. Recently I noticed oil level seems to be rising, about 3 months ago I took a litre of oil out and watched it and a few days ago it seems to have risen to a few mm above 'full' again.
The wife took the kids to the park yesterday and eldest texted me during journey to say car was making a noise. Wife declined to return home and continued to destination. On their return shortly after departing, car got slower and slower and stopped (while making bad noises), refusing to restart.
Eldest says car was initially making a noise like a toy car / like my dewalt drill spinning. Then other sounds started (scraping noise and a noise like metal was being dropped on to the road!)... obviously she is an 11 yr old and I can't trust her recollection completely but she is quite switched on.
I cleared a load of codes from the computer, and now no codes are coming back (there were plenty originally which are saved). I can start the engine (with the oil cap off) and no codes occur. If I do this a volcano of oil and gas (a bit smokey gas, smells like exhaust fumes - not that bad) comes out of the oil hole (or the hose that connects the rocker cover to the air intake hose pre turbo, or the dipstick hole if the dipstick is removed - any will work to keep the engine running). In messing round with it for 2 or 3 hours and perhaps 20 short starts not a single code has come back.
I then put all the hoses back to normal and tested it again and it dies after seconds again. Then removed the flexible air hose running to the anti judder valve (on the input side of the intake manifold, so it can suck air directly into the manifold) and its fine again (runs indefinitely), but a bit of smoke is still coming out of the flexible hose I have removed (so smokey gas is going through the rocker cover -> intake hose pipe, through the turbo air side, through the intercooler and out of the hose that would normally connect to the intake manifold - also through the air filter and out of the main air intake).
So, my guesses are that the 'smokey gas' is exhaust gas depleted of oxygen. So something is causing a high pressure of exhaust gas in the rocker cover, could be from the top end of the engine or I assume the bottom in which case its going up to the rocker cover via the engine block oil return channels. This is being recycled into the engine and the engine is starved of oxygen so stops.
Theres a couple of ideas in that other thread - turbo blown and blocking exhaust output, loose injector, but the loose injector seems to have been dismissed, and my turbo *seems* ok - I can stick my fingers into the intake and the shaft only has perhaps a mm or less radial play, and I think I heard it spin up slightly (not sure about that - to check later).
The most interesting theory from the other thread was that a blocked turbo exhaust port would cause exhaust gasses to pass through the turbo oil return pipe into the crankcase, up the oil return channels to the rocker cover and hence out. But I imagine also possible is a head gasket allowing gas from 1 cylinder to go directly into an oil channel in the head?
Coolant and oil look fine, no milk etc. Is a badly blocked DPF possible? I was wondering if I could loosen the lambda sensor for instance and allow the exhaust gas to escape that way to test it. One last thing, the fuel is just above zero and the wife swears blind that its used a quarter of a tank in 15 miles. I don't really believe it but I thought I would mention.
Any ideas would be really appreciated.
History: Car is Seat Alhambra 2011 2.0 TDI engine code CCF with 170k on clock. Recently I noticed oil level seems to be rising, about 3 months ago I took a litre of oil out and watched it and a few days ago it seems to have risen to a few mm above 'full' again.
The wife took the kids to the park yesterday and eldest texted me during journey to say car was making a noise. Wife declined to return home and continued to destination. On their return shortly after departing, car got slower and slower and stopped (while making bad noises), refusing to restart.
Eldest says car was initially making a noise like a toy car / like my dewalt drill spinning. Then other sounds started (scraping noise and a noise like metal was being dropped on to the road!)... obviously she is an 11 yr old and I can't trust her recollection completely but she is quite switched on.
I cleared a load of codes from the computer, and now no codes are coming back (there were plenty originally which are saved). I can start the engine (with the oil cap off) and no codes occur. If I do this a volcano of oil and gas (a bit smokey gas, smells like exhaust fumes - not that bad) comes out of the oil hole (or the hose that connects the rocker cover to the air intake hose pre turbo, or the dipstick hole if the dipstick is removed - any will work to keep the engine running). In messing round with it for 2 or 3 hours and perhaps 20 short starts not a single code has come back.
I then put all the hoses back to normal and tested it again and it dies after seconds again. Then removed the flexible air hose running to the anti judder valve (on the input side of the intake manifold, so it can suck air directly into the manifold) and its fine again (runs indefinitely), but a bit of smoke is still coming out of the flexible hose I have removed (so smokey gas is going through the rocker cover -> intake hose pipe, through the turbo air side, through the intercooler and out of the hose that would normally connect to the intake manifold - also through the air filter and out of the main air intake).
So, my guesses are that the 'smokey gas' is exhaust gas depleted of oxygen. So something is causing a high pressure of exhaust gas in the rocker cover, could be from the top end of the engine or I assume the bottom in which case its going up to the rocker cover via the engine block oil return channels. This is being recycled into the engine and the engine is starved of oxygen so stops.
Theres a couple of ideas in that other thread - turbo blown and blocking exhaust output, loose injector, but the loose injector seems to have been dismissed, and my turbo *seems* ok - I can stick my fingers into the intake and the shaft only has perhaps a mm or less radial play, and I think I heard it spin up slightly (not sure about that - to check later).
The most interesting theory from the other thread was that a blocked turbo exhaust port would cause exhaust gasses to pass through the turbo oil return pipe into the crankcase, up the oil return channels to the rocker cover and hence out. But I imagine also possible is a head gasket allowing gas from 1 cylinder to go directly into an oil channel in the head?
Coolant and oil look fine, no milk etc. Is a badly blocked DPF possible? I was wondering if I could loosen the lambda sensor for instance and allow the exhaust gas to escape that way to test it. One last thing, the fuel is just above zero and the wife swears blind that its used a quarter of a tank in 15 miles. I don't really believe it but I thought I would mention.
Any ideas would be really appreciated.
