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 :D , no silly ideas boys :ROFL:
- 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.

Added the link for the mini ratchet which you will need to remove the bracket bolted to the bottom of the manifold.
http://www.screwfix.com/p/titan-scre...questid=550707

Wow, thanks so much, that's really, really helpful. I am surprised how much carbon there was in that engine, considering I've always read that the BSM engine doesn't suffer as much as most with carbon build-up!

You did a really good job in cleaning that out. How long did it take you in all?

Did the toothbrush have any effect at all on the carbon deposits? I always imagined carbon deposits to be super hard and stuck fast. I've had some reasonable luck using a steam cleaner to get carbon off an exhaust, so I'd like to try it on the backs of the valves.

I don't know if I'm quite brave enough to tackle this myself though... I had to work myself up to installing the umbrella holder in the boot!

Cheers Tony +++
I am please with the results.
It took me about a week, but only because I was doing manifold at the same time and working as well.
If you jump on it and focus only on the decoke it's about up to two days non stop.
Deposit on the walls is very soft and very hard on the plates and valve heads.
Toothbrush is not the tool for the job, but it helps you to get to the edges of valve heads in certain spots, but only after removing most of the build up and soaking it for a while in the degreaser.
What you don't want is to spray the degreaser from the beginning as it gets very messy and you can't see sh1t and it's hard to vacuum it out properly with either wet or normal vac. Get as much dry, hard and greasy deposit with a dry vac first and only then introduce degreaser me finish the job with it.

That is very detailed Marcin! Looks like a lot of work, patience, and swearing!

What does the performance feel like now you've done it?

Precisely mate
I haven't driven the car prior to that and at the same time I have deleted manifold flaps completely, but Del was staying at mine over the weekend and after an hour and a half of driving and hunting down a BBQ after "season" he definitely noticed a bigger roar from the engine and exhaust plus a performance difference.
How much I don't know as I haven't done the dyno run before hand.
Next step is to clean injectors and rolling road remap with all the graphs before and after so I will have some live data from the car after decoke and no flaps before remapping it.

Excellent write up thanks Marcin - added to sticky for reference +++

Great job mate, truely.
Forgive my complete ignorance here.
When you say flaps delete, do you mean that you just took them out completely and didn't put them back whem rebuilding the intake??

Hi Rick
Have a look at this thread, it should give you all the answers you are looking for +++

http://forum.a8parts.co.uk/showthread.php?t=12128

Marcin,
If you had to do this again and you had the option, do you think a blaster with a media like crushed walnut shells would be a way to go? Do you think it would speed the process up?