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Lockey
Member Since: 13 Dec 2016
Location: Limerick
Posts: 111
  
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Ok! so a bit of progress today, the front P/S cylinder was checked with a boroscope today, and theres stuff in there that really shouldnt be there it seems.. the mechanic is going to do a check on the two other cylinders on the bank and see are they the same, but it looks like a cam chain has snapped.
Im going to call down myself and have a look with him in about an hour and determine the best course of action but its looking like new engine time  any of ye guys have experience with this failure? anyone rebuild an engine with this failure?
Cheers,
C
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 23rd Jan 2017 4:10 pm |
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Rich84
Member Since: 25 Jun 2013
Location: South Australia
Posts: 238
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Was there any scoring to the cylinder? Specific tools are required to machine compacted graphite iron blocks as the material structure of CGI is different (harder) than normal grey iron/cast iron. Also I'm not sure if oversize pistons are available for TDV6. I do know that normal aftermarket pistons are available.
Clearly there will be some damage to the valves/head. Might be worth taking the head off to inspect and making a decision from there. 2008 RRS TDV6 - Chawton White/Black/Lined Oak - 20's, h/k, sunroof - 350K KM.
2010 Audi A6 3.0T S-Line - Phamtom Black/exclusive 2-tone valcona 184K
2000 Audi A4 avant 1.8t Q Sport - Phantom Black/black 385K KM
1990 Nissan Pintara TRX - red - lots of mods - 439K KM
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| 23rd Jan 2017 10:37 pm |
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Lockey
Member Since: 13 Dec 2016
Location: Limerick
Posts: 111
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Ok false alarm! I went down and inspected with the boroscope myself (He had just picked it up yesterday and wasnt familiar with the workings of it) He had been looking too closely at the piston, and was looking at the combustion chamber in the piston (not sure the technical name for this?) so i turned the engine over by hand till the piston was at BDC and we could see the whole lot, all 3 pistons on the P/S are washed clean with diesel, look absolutely fine, and show no signs of interferance with the valves, theres a decent bit of diesel still sitting in the cylinders, this is contrasted with the three D/S cylinders which are black with soot (presumable from trying to compensate for the three non firing cylinders?).
So my conclusion of this is that there is a compression or timing issue of some sort.
-All 6 injectors are clearly firing.
-D/S bank is working, P/S bank is not.
-P/S bank is getting fuel, only other think it needs is compression to run.
Likely Culprits:
-Injector timing is wrong somehow? opening the injectors on the exhaust stroke?
-a very odd failure of the HG, where it has failed equally across all three cylinders?
-Timing has slipped on a camshaft, and the exhaust/intake valves are staying open too soon/too long and impedeing compression on one bank.
Anyone got any thoughts on this??
Cheers!
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| 24th Jan 2017 9:09 am |
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hugeviking
Member Since: 08 Jun 2010
Location: cotswolds
Posts: 1482
 
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Think your going to have to check the valve timing
Andi.
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| 24th Jan 2017 6:39 pm |
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Rich84
Member Since: 25 Jun 2013
Location: South Australia
Posts: 238
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Did you not say that you'd already done a compression test with satisfactory results?
Would've thought that would rule out a valve timing issue or a loss of compression through the HG.
Any further developments on where all that swarf in the fuel tank came from? 2008 RRS TDV6 - Chawton White/Black/Lined Oak - 20's, h/k, sunroof - 350K KM.
2010 Audi A6 3.0T S-Line - Phamtom Black/exclusive 2-tone valcona 184K
2000 Audi A4 avant 1.8t Q Sport - Phantom Black/black 385K KM
1990 Nissan Pintara TRX - red - lots of mods - 439K KM
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| 24th Jan 2017 9:41 pm |
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Lockey
Member Since: 13 Dec 2016
Location: Limerick
Posts: 111
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Hey Rich84,
Yeah weve done a compression test using an oscilloscope and all seemed good, i guess im just second guessing it with the latest hard evidence that i have (Im not the biggest fan of the oscilloscope, would much prefer a mechanical test  )
But you are correct, taking the compression test into account, rules out timing and compression issues also and really only leaves electronic failure as the root cause.
No idea where the metal swarf came from, but can only assume it was the HPFP. the fact that the HPFP is now changed and theres no improvement, leads me to assume, the metal swarf is from an original HPFP, and that nobody cleaned the tank out after its failure, and just replaced the HPFP with the one i pulled out and replaced a few weeks ago either way, HPFP is now definitely a good unit, and LPFP is inspected and bench tested, so neither could be the problem.
im at a loss at this stage
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| 25th Jan 2017 9:14 am |
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Erea
Member Since: 19 Mar 2012
Location: Munster
Posts: 1509
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Lockey wrote:Ok false alarm! I went down and inspected with the boroscope myself (He had just picked it up yesterday and wasnt familiar with the workings of it) He had been looking too closely at the piston, and was looking at the combustion chamber in the piston (not sure the technical name for this?) so i turned the engine over by hand till the piston was at BDC and we could see the whole lot, all 3 pistons on the P/S are washed clean with diesel, look absolutely fine, and show no signs of interferance with the valves, theres a decent bit of diesel still sitting in the cylinders, this is contrasted with the three D/S cylinders which are black with soot (presumable from trying to compensate for the three non firing cylinders?).
Cheers!
Surely if there is compression in the cylinders and diesel in there, those cylinders should fire momentarily if only to burn off that excess diesel? Even without the injectors I thought, with enough compression the diesel should self ignite (I'll duck now as the rudimentarys of a Diesel engine are explained  )
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| 25th Jan 2017 11:19 am |
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Lockey
Member Since: 13 Dec 2016
Location: Limerick
Posts: 111
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fully inclined to agree with you Erea.. however, my thinking is, that one of two things is happening:
A: My compression test is inaccurate and in fact dont have compression on the P/S bank (This could be caused by timing slipped a tooth or three, blown HG, lobes spun on the camshaft causing timing to be out..etc)
B: Compression is good, and for some reason, electronically the injector pulse timing is out (This is what the original fault codes are indicating) and hypothetically the injectors are firing at some point in the exhaust stroke, so 90% of the injected fuel goes out the exhaust.
Ive no idea if be is possible, or how i could test it, but its looking more and more likely to be the culprit..
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| 25th Jan 2017 3:14 pm |
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hugeviking
Member Since: 08 Jun 2010
Location: cotswolds
Posts: 1482
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Presumably the oscilloscope shows resistance of the compression stroke or resistance of another "type",
Ie mechanical contact.
Is it possable to cross any pipe work from the HPFP ?? Injector wiring??
Andi.
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| 25th Jan 2017 9:16 pm |
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Lockey
Member Since: 13 Dec 2016
Location: Limerick
Posts: 111
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The oscilliscope shows the draw on the battery to turn the engine over on each compression stroke of each cylinder, it shows this as a sine wave type graph, provided the engine is mechanically healthy, the graph should be sinusoidal or even, all waves should be the same distance apart and peaking at the same point.
This shows that the timing is correct and the compression is good on all cylinders... theoretically. And thats how it appeared in the test i did a few weeks back. I am a bit wary of this type of test though and would prefer to get a mechanical compression test done for a more accurate reading of each cylinder.
As for crossing pipe work from the HPFP, im not really sure what you mean? i have tested the wiring to each injector and they seem to pulsing, what i can t be sure of is if theyre pulsing at the right time. Theoreticaly i could probably get a 2nd input from the cam position sensor and match this to injector pulse to see is it firing at the right time.
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| 26th Jan 2017 10:43 am |
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hugeviking
Member Since: 08 Jun 2010
Location: cotswolds
Posts: 1482
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Hi Lockey,
I was just thinking aloud i suppose. I just wondering if any pipework or wiring could have been crossed at some point, perhaps by the previous owner ( you bought it as a non runner ??)
Andi.
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| 26th Jan 2017 5:20 pm |
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Lockey
Member Since: 13 Dec 2016
Location: Limerick
Posts: 111
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Ah i see where youre coming from now. Its unlikely that a wrongly plumbed or wired system is the fault as the initial failure the previous owner witnessed was a sudden loss of power on the motorway, followed by the usual array of warnings and bells, special functions restricted, lowered suspension etc.
So it was working, and then this happened.
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| 27th Jan 2017 11:38 am |
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hugeviking
Member Since: 08 Jun 2010
Location: cotswolds
Posts: 1482
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Would a snapped cam chain on the LH bank ( passenger) affect drive to the HPFP ?
Andi.
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| 27th Jan 2017 2:47 pm |
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Lockey
Member Since: 13 Dec 2016
Location: Limerick
Posts: 111
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No it wouldnt, and would display the symptoms were seeing here. but its mostly ruled out seeing as theres no sign of the valves hitting the piston heads. we'll be pulling the rocker cover soon so we can be sure of this among other things, so we'll be able to rule it out soon 
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| 27th Jan 2017 2:55 pm |
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hugeviking
Member Since: 08 Jun 2010
Location: cotswolds
Posts: 1482
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Best of luck 
Andi.
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| 27th Jan 2017 6:53 pm |
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