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Old 14th September 2016, 08:44 PM
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M-A8 M-A8 is offline
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Join Date: Aug 2012
Location: SE
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Default S8 5.2 V10 Decoke (carbon build up)

Hi folks

First of all massive thanks to Del for mental support and giving me confidence which allowed me grow a pair and complete this process along with manifold split, flaps delete and compression test. Also thanks to Scott and my mate Grant who was holding the torch above the inlets in the moments when I was missing 3rd hand

I've been absent for a while and I'm making my way back slowly.
I was ridiculously busy for the past 18 months and especially last 6 months and to top it up I got myself a little S8 project car for my 33rd birthday, mainly to drag myself out of work from time to time and one of the things to do on the list was a full decoke inc. inlet manifold variable flaps, but I will cover this part in more detail in the Inlet Manifold Flaps Delete thread.

I've completed the process over the week time mainly due to work and doing inlet manifold at the same time along with other jobs.

Depends how far you want to go (full on decoke is the only way in my mind) I still don't think this process can be done in one day. Inlet manifold itself is a pain to remove to start with, not like on V8 petrol engines when the whole process was very quick.

I followed this guide in order to remove the manifold.
http://audirevolution.net/forum/index.php?topic=3221.0

Please note:
- Inlet wont come out just like that like this guy claims
- You will have to remove both fuel pumps, one on each side of the manifold
- Remove two the most obvious and easiest to undo fuel lines and move them aside.
- This is the worst part which he did not mention at all, unless someone had his manifold out before and did not bother to bolt on the electrical connectors bracket for the fuel injectors which is bolted by two torx bolts to the bottom/front manifold and which will prevent you from removing the manifold.
You WILL NEED a pair or small hands, lots of patience and this mini ratchet with a torx bit (T25 or T30) on the end to unbolt the bracket. This is one of them bolts I've dropped and recover using endoscope camera and grap tool. Both bolts are visible thru the square cut out with the pin in the middle of the crash frame where the bonnet's latch goes.
http://www.screwfix.com/p/titan-scre...questid=550707

What I've used to do the job:
- Wet vac with a 10mm rubber pipeline taped around at the end (sorry no picture, should have take a pic of each vac setup)
- Standard vac with a 20mm plastic flex hose taped to the end.
- Tooth brush
- Long ish reach flat head screwdriver with the last 15mm bend slightly (it makes huge difference when cleaning walls and edges of the valve heads
- Approx. 8-10 cans of WD40 Specialist Fast Acting Degreaser (thats just for inlets and valves). People will tell you to use gunk or whatever but this stuff is fantastic and I've tried most available stuff on the manifold and they were not as good as WD40 stuff
http://www.screwfix.com/p/wd-40-spec...FUqdGwodPXwGxg
- Cordless drill
- Wire brushes (for the drill)
https://www.amazon.co.uk/dp/B00BCY5S...eywords=982654
- More wire brushes
https://www.amazon.co.uk/175MM-BRUSH...wire+brush+set
- Box of latex gloves , no silly ideas boys
- Few green scouring pads
- Pack of 10 microfibre cloths, 5 of them cut in half and rolled up to block the inlets after cleaning and two with open valves prior to cleaning to avoid crap going into the cylinder.

This process will also involve:
- removing chunky 40Amp fuse above the batter
- removing both undertrays, big one under the engine and small one just behind it and jacking up one side of the car in order to disconnecting engine position/speed sensor which is between the engine and gearbox, easy access

The above is the prep work for the cylinders compression test which is worth doing while you doing decoke, but also 2 out of 10 valves will always stay open so you will have to crank the engine and very quickly turn the ignition off to allow both open valves to shut.

Also while you doing this, its worth pulling coil packs with the spark plugs and dropping endoscope camera down each cylinder and inspect each cylinder, only if you are as an@l as me.
https://www.amazon.co.uk/dp/B00KV669...ower+borescope
...and if you are as lucky as me and will manage to drop a bolt down and get it stuck between the radiator and fan, this camera and grab claw tool will save your day.

It's worth mentioning that my oil separator wasn't performing as it should and on top of it I've had one internal flap broken off and remaining 4 flaps on the same run very loose so that would slightly contribute to a little of extra build up.

Process:
Lets start from the inlet plates. Remove as much build up as possible, put all the plates in the bowl and let it soak in the degreaser while you are working on the inlets.

Inlets, this is how completed this process with a great result at the end.

1. Scrape off as much build up as possible with the slightly bend flat head screwdriver. Inlet walls first.
2. Vacuum out.
3. Use either plastic or brass wire brush on the drill (avoid steel brushes).
4. Vacuum out.
5. Valve heads - this is the worst part as they get very hot so the build up is rock hard and stuck well, it's where you will spend most of the time.
6. Vacuum out.
7. Spray the walls with the degreaser using the narrow nozzle to flush it all off.
8. Suck it with a wet vac and inspect places you've missed.
9. Carry on using combination of toothbrush, wire brush (drill), normal wire brush, green scouring pad until all or almost all of the build up is gone.
10. Fill up the inlet with the degreaser (3/4) and run it over with a plastic wire brush on the drill. You will have to try all sort of angles to clean the edges of the valve heads which you can't always see and valve rods/shafts from behind.
11. Suck it all with wet vac
12. Fill the inlet with degreaser again flushing inlet walls at the same time
13. Suck it all out with the wet vac.

Then inspect and if you are happy move on to the next one and repeat the process 9x more times, if you still can see bits left behind use appropriate tools. I wasn't happy with few of them so I was doing it over and over again

Apologies if some of it may not make sense or it's just too much detail for your liking, I wanted to describe this process as well as possible and as quickly as possible for Tony to decide if he wants to do it himself or get the garage to do it.

Photos attached, any questions please ask.
I've attached also few shots of inlet's variable flaps which I have decoked while having manifold split, doing it on the manifold in piece would be a pain and to do the job properly you need access from inside the manifold - you will need at least two days to split the manifold, clean it inside and the flaps of course, removing flaps is easy, then cleaning the silicon off which is a pain, putting it back and resealing it inc. bolting back on flap motors and all that.
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__________________

2006 D3 S8 5.2 V10
Ceramic Brakes, Bang&Olufsen, DTV, DAB, Rear Camera, BT, TPMS, Soft Close, Auto Boot, AMI , 4 Zone AC, Home Link, All Electric Blinds, Fingerprint, Ski Hatch, Black Extended Leather, Heated Sport Seats, Alacantra, Carbon Trim inc Aluminium Pack 2.
2015 A3 S line 1.4 TFSI - for the missus to keep her away from my car.
Standard S-line equipment, no extras.
2006 D3 A8 3.7 V8 - SOLD but not forgotten

Last edited by M-A8; 15th September 2016 at 07:46 AM.
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