S8 5.2 Intake Manifold removal and cylinder cleaning
12-22-2012, 12:28 AM
#12
AudiWorld Wiseguy
Walnut shell blasting
Cylinder head removal is definately not required, only intake manifold removal. Have a look here.
http://www.e90post.com/forums/showthread.php?t=682116
Excellent DIY instructions, albeit for a BMW but exact same issue. Explains the process in detail and the tools BMW/MINI dealers use to clean the intakes out. My MINI which has a DI engine needed a clean after only 20k. It was done "on the house" and it made a hell of an improvement.
Walnut shell blasting tools can be rented so this should make the job a much more feasable DIY prospect, but it can be purchased easily enough. In fact ECS tuning sell them
http://www.e90post.com/forums/showthread.php?t=682116
Excellent DIY instructions, albeit for a BMW but exact same issue. Explains the process in detail and the tools BMW/MINI dealers use to clean the intakes out. My MINI which has a DI engine needed a clean after only 20k. It was done "on the house" and it made a hell of an improvement.
Walnut shell blasting tools can be rented so this should make the job a much more feasable DIY prospect, but it can be purchased easily enough. In fact ECS tuning sell them
12-22-2012, 08:22 AM
#13
AudiWorld Super User
Only thing I am concerned about is lose deposits that will stay around valves. Vacuuming or blowing can't clean all. That dust can stuck valves opened or jam piston rings.
That BMW shouldn't be cleaned at all at the first place. Those ware minor deposits that barely "painted" intake and valves.
It is interesting that everybody is talking about cleaning and not about preventing. If Mini had to be cleaned after 20K it will have to be cleaned again after 15K and so on. Deposits generally came from oil, but also from a low quality fuel. FSI only oil. That oil comes from the crank case ventilation that by low has to go trough the combustion process. There are systems that should prevent any oil to go that way, but not all of them are perfect. Another way to get oil there is around intake valves if they are not perfectly sealed. Just cleaning deposits without addressing this is ridiculous. And to address leak around valve steams head has to come off.
That BMW shouldn't be cleaned at all at the first place. Those ware minor deposits that barely "painted" intake and valves.
It is interesting that everybody is talking about cleaning and not about preventing. If Mini had to be cleaned after 20K it will have to be cleaned again after 15K and so on. Deposits generally came from oil, but also from a low quality fuel. FSI only oil. That oil comes from the crank case ventilation that by low has to go trough the combustion process. There are systems that should prevent any oil to go that way, but not all of them are perfect. Another way to get oil there is around intake valves if they are not perfectly sealed. Just cleaning deposits without addressing this is ridiculous. And to address leak around valve steams head has to come off.
12-22-2012, 12:02 PM
#14
AudiWorld Wiseguy
I'm aware of all that but the fact of the matter remains that not even the manufacturers seem to have solved this problem yet so Joe Schmoe hasn't got much hope. In the meantime those of us with DI engines are stuck with having to clean them periodically, or butcher the crankcase breather system which usually results in codes being thrown and problems passing emissions tests.
Whether or not that BMW needed to be cleaned is not relevant, it's the "how to" that matters. However the reason walnut shells are used is because at worst a couple of bits of ground walnut shell ending up in the cylinder is no big deal. It's much much softer than any other material in there, and is quickly burned away to nothing. Same for any residual carbon deposits...and lets not forget where they came from in the first place.
Sure you can take the heads off and make a huge deal of the job, however the cost/benefit of doing this over the walnut shell blasting doesn't make any sense.
Lastly, that business about it being caused by low grade fuel and oil is total BS. That line is spun by the manufacturers to try and shift the blame for their fundamental design flaw onto user error. My MINI has been run on nothing but OEM oil from the dealer and BP or Shell's finest since new, and it was all coked up after only 20k. That's not user error.
Whether or not that BMW needed to be cleaned is not relevant, it's the "how to" that matters. However the reason walnut shells are used is because at worst a couple of bits of ground walnut shell ending up in the cylinder is no big deal. It's much much softer than any other material in there, and is quickly burned away to nothing. Same for any residual carbon deposits...and lets not forget where they came from in the first place.
Sure you can take the heads off and make a huge deal of the job, however the cost/benefit of doing this over the walnut shell blasting doesn't make any sense.
Lastly, that business about it being caused by low grade fuel and oil is total BS. That line is spun by the manufacturers to try and shift the blame for their fundamental design flaw onto user error. My MINI has been run on nothing but OEM oil from the dealer and BP or Shell's finest since new, and it was all coked up after only 20k. That's not user error.
12-22-2012, 01:19 PM
#15
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Only thing I am concerned about is lose deposits that will stay around valves. Vacuuming or blowing can't clean all. That dust can stuck valves opened or jam piston rings.
That BMW shouldn't be cleaned at all at the first place. Those ware minor deposits that barely "painted" intake and valves.
It is interesting that everybody is talking about cleaning and not about preventing. If Mini had to be cleaned after 20K it will have to be cleaned again after 15K and so on. Deposits generally came from oil, but also from a low quality fuel. FSI only oil. That oil comes from the crank case ventilation that by low has to go trough the combustion process. There are systems that should prevent any oil to go that way, but not all of them are perfect. Another way to get oil there is around intake valves if they are not perfectly sealed. Just cleaning deposits without addressing this is ridiculous. And to address leak around valve steams head has to come off.
That BMW shouldn't be cleaned at all at the first place. Those ware minor deposits that barely "painted" intake and valves.
It is interesting that everybody is talking about cleaning and not about preventing. If Mini had to be cleaned after 20K it will have to be cleaned again after 15K and so on. Deposits generally came from oil, but also from a low quality fuel. FSI only oil. That oil comes from the crank case ventilation that by low has to go trough the combustion process. There are systems that should prevent any oil to go that way, but not all of them are perfect. Another way to get oil there is around intake valves if they are not perfectly sealed. Just cleaning deposits without addressing this is ridiculous. And to address leak around valve steams head has to come off.
I'll agree, however, that that Mini did not need cleaning yet. My friend's S6 at 40k was 13 times worse than that, and certainly needed cleaning.
As to what causes this, I'll agree that the manufacturers still have a lot of work to do in curing this problem on the DI engines, and until they figure this out, I think simply accepting this as a maintenance item is the best you're going to get.
12-22-2012, 03:30 PM
#18
AudiWorld Super User