Apologies for the layout, I could not find how to do it cleanly, or move things around.
This is for an Australian (RHS drive) 2010 Touareg 7L6 TDI 3.0 litre, 176 Kw CASA engine.
Mileage was at 270K. The upper inlet manifold removal is straightforward, the PDF of the VAG manual that
c4ar kindly shared recently is correct.
The fuel connection pipe was empty when loosened and lifted up, so there was no diesel mess. It does indeed need to be undone, there is definitely no space to slide the manifold out unless the connection pipe is loosened / removed.
The electrical connector under the throttle valve that has to be undone and is tricky to grip properly, I had to use small short screwdriver from below to push in the clip to free it, it came off easily then. A mirror, then finger feel, helps to find the right spot.
Bolts are all easy access, except for one, and are an easy undo as the torque is only 9 Nm. The tricky bolt (looking at the engine from front) is at the rear left of the right-side manifold arm. There is a T-piece coolant connector there (red screwdriver tip points to it in image), the rubber hose connection rearwards back to the radiator tank (the tube can be seen running from ~ center to the top of the image). It’s a long T-connector with two lips on it, so the squeeze clip needs to be taken well away from its normal position, back towards the firewall.
There was no gasket between the EGR pipe and the manifold when I opened it up, so I’m guessing the manifold had been cleaned by a previous owner who lost / forgot to replace it. But there was no evidence of leaks there, the surfaces are smooth and mated well, I put it back the same and will source a gasket and do later.
As expected the carbon deposits were significant throughout the manifold, up to perhaps 5 mm deep in places, mostly 3-4 mm on most walls.
My back of envelope calculations of the reduction in flow this would cause (assuming no turbulence – not likely to be true ) is that if a ~50 mm (average, guessed representative value) diameter pipe is reduced to a diameter of 46 mm, that’s a 15 % reduction in flow; if a 40 mm pipe reduced to 36mm it’s a 19% reduction. So it ought to make a real difference cleaning it out. I guess it would have a similar effect to replacing an air-filter that was really dirty.
I bought some Liquimoli (Diesel Engine Intake Decarb) as used by Stranga
(
)
to help dissolve the carbon deposits in the removed manifold, but one can definitely won’t do it. I did find that standard carburettor-cleaner cans - usually around on special - did a similar job, but at 1/3 the cost 😊. The hack of using several (larger size) long zip-ties, held in and rotated by a portable drill, to attack the deposits on the deeper inside regions of the manifold worked quite well too. But it’s easy to get bits of carbon / black sludge flicked on to you when moving it back and forth, take care. Also, bind the drill end of the pointer-end of the cluster of zipties with electrical tape first, so that the chuck has something firm to grip down on when tightened.
It is a really messy job as other posts have mentioned, I used lots of gloves and paper towel. After physically removing what I could, then spraying / soaking in fumes to get to the rest softened as much as possible (with plastic bags rubber-banded over the openings to keep the vapours in there, for 30 mins in the sun), I pulled through disposable cotton rags to get as much as I could out. Finished off with a degreaser spray, and then a Karcher high pressure squirt through. I did not get it back to shiny metal (was not trying to), but the surfaces were quite smooth and there was no obvious moveable carbon deposit in any of the blacker-coloured areas.
(I knew I did not have time to do the lower inlet manifolds on each side, but they will be worth doing when I can get that time. I’ve included images that show the varied height of the carbon there).
After reinstalling – nothing special just the reverse of removal- it took about 20 secs for the fuel to refill while cranking for the engine to start, but it was fine after that. A short drive suggested there was a smoother take-off, but I have a 3 hour trip towing a trailer-sailer next week so I’ll report back on any differences after that.
(Later, after our long trip): Very obviously better slow speed take off, smoother and less delay in take up from the accelerator push down. We also got perhaps 1.5 l/100km better mileage that before when towing the trailer-sailer (at approx. 100km, for several hours, as displayed by the dashboard “average-use” calculation for this Touareg). Kickdown is still sluggish from 100kph for overtaking, but no different to before.
That’s all, hope you CASA people find this of help.
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