A8 Parts Forum  

Go Back   A8 Parts Forum > General Natter > Daily banter

Daily banter For everything, and anything that doesnt fit in elsewhere

Reply
 
Thread Tools Display Modes
  #31  
Old 10th April 2018, 12:57 PM
MikkiJayne MikkiJayne is offline
Senior Member
 
Join Date: Jan 2012
Posts: 5,017
Default

Its very strange for sure. I might see if I can find some documentation on the spray pattern and try and calculate if its being disrupted.
Reply With Quote
  #32  
Old 10th April 2018, 01:00 PM
HPsauce HPsauce is offline
Senior Member
 
Join Date: Sep 2011
Location: Chilterns, almost over HS2!
Posts: 8,366
Default

Could it be due to a pressure differential between the combustion chamber and behind the cylinder?
A high revs (implies high power) there's more fuel and more combustion so higher pressure. At lower revs/power/pressure the oil works up past the pistons and is burnt.

Not sure that 100% makes sense.....

Is there evidence of burning oil in the exhaust when running at lower revs?
Difficult to test unless you have a dyno I guess.
__________________
2003 D2 FL S8. Irish Green Pearl/Beige. Solar sunroof, auto-dim mirrors, electric rear seat functions, ski hatch retrofit; extended leather. Aftermarket DVB-T, reversing camera and full XCarlink (Bluetooth etc.).
2016 Volvo V40 T5 Cross Country (4WD) with ALL the toys including adaptive cruise etc. etc. Osmium Grey with Blonde/Charcoal leather interior. Polestar performance "optimisation". (A much rarer model than a D2 S8 by the way!) Oh, and a brand new engine at just under 30,000 miles on the factory one!
Finally: gone, but not forgotten.....
1998 D2 PF S8. AgateGrey/Platinum. Every option (I think) except electric rear seats, tiptronic steering wheel, ski hatch, towbar & dimming door mirrors.
e.g. Cruise control, NavPlus/TV, Bose, GSM, Xenons, Solar roof, Parking sensors, Alcantara/leather everywhere of course. (internal dimming mirror added later)
1998 (very early) Ford Focus 1.8 Zetec; ABS/TCS, Heated screen/mirrors, Aircon, Auto-dim mirror, Leather, Trip computer, Cruise control, OEM Ford SatNav with CD changer.
And before that a lot of Rover 800s, a few oddities, a lovely Triumph Dolomite 1850HL with Overdrive and way back in my schooldays an Austin Seven aka Mini 850!
Reply With Quote
  #33  
Old 10th April 2018, 04:43 PM
Dezzy's Avatar
Dezzy Dezzy is offline
Senior Member
 
Join Date: Sep 2009
Location: N. Devon
Posts: 2,715
Default

If the bores are being washed I'd expect the oil (what's left of it to smell a bit petrolly) If she's burning it should soot the plugs and be a bit gunky?

T8 uses a drop and you can see it being burnt at high speeds, will leave a blue smoke trail >140. never seen it at lower speeds but she'd still use a drop, sometimes she'd smoke a bit at start up
__________________
1996 A8 4.2 QS. Bose, Solar roof, um...um... rally sport towbar. Now gone to a new home as the Traders 8.

Bright yellow bus o love.
Reply With Quote
  #34  
Old 10th April 2018, 10:09 PM
MikkiJayne MikkiJayne is offline
Senior Member
 
Join Date: Jan 2012
Posts: 5,017
Default

I haven't pulled the plugs yet, but at the moment I'm fairly sure it's blow-by. The oil breather pipework has liquid oil in it which is unusual. Normally its sooty sludge, not clean liquid oil. I think what is happening is that at low rpm the rings are quite loose in the bores and so combustion gases get in to the sump and push the oil vapour out of the breather system and then in to the intake manifold. Exactly how its supposed to work, but more than is supposed to happen. At high rpm there is enough combustion pressure behind the rings to seal them in the bore hence lots of power and no oil usage. Pretty much as you described Andrew The oil smells fine - no fuel in it.

Vera says there is a puff of smoke when setting off - I think this is oil that has settled in the separator pod being pulled through the engine. There's no sign of it in the exhaust so it is definitely burning and not blowing straight through.

I've finished pulling things from the old engine and started putting them on the new engine.



Oil cooler / filter housing cleaned up, fitted with a new cooler, filter, pressure sensor, connecting pipe and bolts.



We replaced the timing belt too. The old one is in visibly perfect condition since its only ever been run in at the factory, however it is 18 years old! Its a no-brainer to replace it at this point. Imagine the shiny new belt behind the shiny new covers, since I forgot to take a pic. You know what that looks like by now anyway



Fitted the main water pipes from the old engine to the new one. The pipes that came with the engine didn't have the fittings for the aux heater.



LPG injectors installed



I made some 20mm aluminium spacers for the fuel rail. Much better than it just floating there



Engine going back on the jig



Cue angelic chorus: aaaahhhhoooooeeeeeeaaaaaaahhhhhhhh



Factory manual flywheel Replaced since we're in there, along with the clutch of course.



Engine back on the jig. Only 5 of 8 flywheel bolts were delivered so I can't put it all back together yet. The remaining 3 will be here in the morning.



Going back in the car tomorrow after cleaning the engine bay
Attached Thumbnails
Click image for larger version

Name:	WP_20180410_001.jpg
Views:	582
Size:	108.9 KB
ID:	18369   Click image for larger version

Name:	WP_20180410_002.jpg
Views:	541
Size:	104.2 KB
ID:	18370   Click image for larger version

Name:	WP_20180410_004.jpg
Views:	574
Size:	107.1 KB
ID:	18371   Click image for larger version

Name:	WP_20180410_006.jpg
Views:	574
Size:	122.4 KB
ID:	18372   Click image for larger version

Name:	WP_20180410_007.jpg
Views:	558
Size:	102.5 KB
ID:	18373   Click image for larger version

Name:	WP_20180410_008.jpg
Views:	569
Size:	86.8 KB
ID:	18374   Click image for larger version

Name:	WP_20180410_009.jpg
Views:	571
Size:	117.3 KB
ID:	18375   Click image for larger version

Name:	WP_20180410_010.jpg
Views:	562
Size:	89.4 KB
ID:	18376   Click image for larger version

Name:	WP_20180410_011.jpg
Views:	566
Size:	97.8 KB
ID:	18377   Click image for larger version

Name:	WP_20180410_012.jpg
Views:	567
Size:	112.2 KB
ID:	18378  

Reply With Quote
  #35  
Old 10th April 2018, 10:21 PM
Mechcanico Lee Mechcanico Lee is offline
Senior Member
 
Join Date: Jul 2015
Location: St Helens Haydock
Posts: 434
Default

Some good theory’s on the oil consumption , I like the thoughts .

Some of the petrol Vauxhall’s have a pcv unit inside the rocker cover with a take off pipe that comes directly from inlet manifold ( quite a big bore pipe )

This internal pcv valve in the rocker cover fails and on overrun and light throttle loads where manifold vacuum is high it pulls the oil into the manifold and the oil gets burned that way .

There’s a few engines that suffer with high oil consumption that are pcv issues , tell tale is oil filler cap gets sucked on with some vigour or dipstick gets sucked in if you pull it out a touch . The bmw valvetronic suffers with high oil consumption, that has pcv issues

Some of these issues support the ‘ only uses oil at lower revs ‘ lower revs less throttle openings = higher manifold vacuums , more chance of oil getting pulled into pcv .

I’ve never seen this but heard that on some engines where the oil scraper rings are on the piston ,the oil drillings or micro slot passsages through the piston ring landings can get carbonised up so the oil control rings cannot do there job of scraping the excess oil away .

Would of been a good diagnostic lesson to strip that engine Mikki jane to have a look just for the knowledge gains .

Good post carry on with the good work
Reply With Quote
  #36  
Old 11th April 2018, 04:41 PM
MikkiJayne MikkiJayne is offline
Senior Member
 
Join Date: Jan 2012
Posts: 5,017
Default

D2s are never straightforward...


We discovered this 3 inch crack while Vera was cleaning the engine bay



The tig guy is coming tomorrow morning so I can't put the engine back in today as planned.

At the same time, we also discovered the clutch hose was frayed:



Thanks to Goran and Mike, I actually have one of these hoses on the shelf!! Its going to be a pig to change and I still can't put the engine in, but at least we have one.
Attached Thumbnails
Click image for larger version

Name:	WP_20180411_001sm.jpg
Views:	598
Size:	212.3 KB
ID:	18380   Click image for larger version

Name:	WP_20180411_003sm.jpg
Views:	592
Size:	194.6 KB
ID:	18381  
Reply With Quote
  #37  
Old 11th April 2018, 04:47 PM
MikkiJayne MikkiJayne is offline
Senior Member
 
Join Date: Jan 2012
Posts: 5,017
Default

Spin up the engine on the stand to build oil pressure, then we know its all good to go when its back in the car.
Attached Files
File Type: mp4 WP_20180411_008.mp4 (21.23 MB, 273 views)
Reply With Quote
  #38  
Old 11th April 2018, 06:13 PM
Dezzy's Avatar
Dezzy Dezzy is offline
Senior Member
 
Join Date: Sep 2009
Location: N. Devon
Posts: 2,715
Default

Has the car been in a smack at some point? I think I read somewhere the official procedure after an 8 was hit was to remove the engine to inspect the BHD as they can crack. But that weld looks robot welded so wouldn't expect it to fail from a hairline crack from removing the cup to quick.
__________________
1996 A8 4.2 QS. Bose, Solar roof, um...um... rally sport towbar. Now gone to a new home as the Traders 8.

Bright yellow bus o love.
Reply With Quote
  #39  
Old 11th April 2018, 06:14 PM
steamship's Avatar
steamship steamship is offline
Senior Member
 
Join Date: Jun 2013
Location: Londonderry, Northern Ireland
Posts: 2,931
Default

Quote:
Originally Posted by MikkiJayne View Post
D2s are never straightforward...


We discovered this 3 inch crack while Vera was cleaning the engine bay

At least she was in the right place when it was found.
__________________
2001 A8 D2 FL 3.7 Q - LPG Conversion, Engine: AKC, Gearbox:FBB, Colour:LY5X Aqua Blue pearl effect, Interior:WJ light beige/dark beige valcona leather with burr walnut inserts

My DIY jobs - Replaced alarm horn, Replaced Coolant Temp sensor, Updated RNS-D firmware, Installed Reversing Camera and Digital TV, Dashcam Installation, Retrofitted Rear Blinds, Auto-Dimming Rear View Mirror, Chrome Boot Struts

Sold! 2008 S8 D3 5.2 V10 - Engine: BSM, Gearbox:KLW, Colour:LY7F Suzuka Grey Pearl Effect, Interior:Black/Black with Silver/Black valcona leather with carbon atlas inserts, Bang & Olufsen, Heated windscreen, Soft-close doors, TV, DAB, AMI, Quad Zone, Auto Boot, Auto dim Mirrors, Keyless entry, PDC with rearview camera, AFS II Headlights

My DIY jobs - Fan Jet Windscreen Washers, Retrofitted Electric Side Blinds
Reply With Quote
  #40  
Old 11th April 2018, 07:31 PM
MikkiJayne MikkiJayne is offline
Senior Member
 
Join Date: Jan 2012
Posts: 5,017
Default

Quote:
Originally Posted by Dezzy View Post
Has the car been in a smack at some point? I think I read somewhere the official procedure after an 8 was hit was to remove the engine to inspect the BHD as they can crack. But that weld looks robot welded so wouldn't expect it to fail from a hairline crack from removing the cup to quick.
There's no other evidence of accident damage. I believe this is from hitting a pothole and bottoming out as there is also the usual crack in the sound deadening above the control arms too. I've seen another one pull the brace bracket off the chassis leg from the same sort of event.

The tig guy is going to re-melt the weld to fill in the crack and I'm hoping the welding won't melt too much of the paint. Vera went out for a pelican blue aerosol this afternoon so I'm hoping to be able to make it look reasonable afterwards. The weld itself is hidden but some of the paintwork won't be.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 05:37 PM.


Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.