Chris_B

FSI carbon buildup A.K.A. Audi Black Lung

27 posts in this topic

Anyone experienced this, worried about his, doene anythign to avoid this, planning to settle down in the future and retire in the country with this? Erm, perhaps not that last one... :o

I've seen reports of FSI engines getting a carbon build up on the tops of the valves, mainly due to the crankcase breather - oil vapours are recycled into the top of the block to be burnt off in the cylinders. In a non-FSI engine, the valve tops are washed with petrol and only accumulate a hydrocarbon build up slowly. in an FSI engine of course, there's nothing to wash the valve tops, so this becomes a potential problem.

Audi seem to have designed in a triple-cyclone vapour catch, but reports from RS 4 owners in particular indicate that it might not be as effective as hoped.

One possible mitigation is to add a "catch can" to the breather pipe. This is a larger container that the breather passes through, and contains a larger cyclone or baffles to catch oil vapours before they get back to the top of the head.

Anyone had one fitted and then looked to see how much difference it makes?

Obviously, fitting one is technically an engine modification - anyone experienced (or just have thoughts on with no experience - this is TSN!) warranty or insurance issues, either positive or negative?

I guess Audi would have to prove the catch can didn't cause a problem to invalidate the warranty, so that shouldn't be too bad.

What about insurers? Does any modification send them running to the hills, only to be tempted back with huge piles of money, or are there sensible ones out there who realise something that can only improve reliability doesn't suddenly mean you're 73.3% more likely to be involved in a collision?

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Using an oil catch can is a very popular mod on performance MINI's to reduce contaminants from reaching the supercharger and on the BMW 35i engined models (135i, 335i etc) to stop carbon sludge buildup in the intake, intercooler and turbo as they can also suffer from what you term Audi Black Lung.

It works for them so why not an FSI (other than the warranty/insurance issues you stated above).

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I've seen this discussed on many Audi forums and a lot of people are worried about it .... however so far I've not seen anyone post that's affected by it apart from RS4 owners.

It's big bad news for them but I'm not sure if it goes wider than that or if it's just the highly tuned V8 that's suffering.

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Using an oil catch can is a very popular mod on performance MINI's to reduce contaminants from reaching the supercharger and on the BMW 35i engined models (135i, 335i etc) to stop carbon sludge buildup in the intake, intercooler and turbo as they can also suffer from what you term Audi Black Lung.

Interesting. Obviously FSI is possibly particularly prone because the valve tops don't get washed by injected fuel.

It's insurance I really don't know about - don't want insurers getting jittery over something like this and thinking it equivalent to a bit of Barrying. :grin:

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I've seen this discussed on many Audi forums and a lot of people are worried about it .... however so far I've not seen anyone post that's affected by it apart from RS4 owners.

Particularly Americans? I did wonder if more dino would have an affect, as some Americans still want to put dino oil in and change very 5k miles.

But it's an FSI design issue, and the S5 V8 block is close enough to the RS 4 block (heck, all the new cam-chain 4.2 V8s are really) that I'd expect those parts (crankcase breather etc) to be the same.

It may be that lower performance FSI engines don't suffer as much - perhaps to do with oil breakdown? Perhaps the RS 4 uses an oil that's particularly prone to this?

First step is speak to some insurers I guess, see if any will be sensible. Then a quiet word with my dealer service dept.

The can itself is about £200, which is worth it for peace of mind on a car like the S5, IMHO.

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It's big bad news for them...

That's a matter of opinion.

There's been some VERY emotive debate on the subject, with two distinct opinions:

1) the deposits are in places in the inlet manifold that don't affect the airflow, so power shouldn't be affected. This group suggest that owners do an acceleration test - and AFAIK owners that have done this have either not had a problem or have had a problem with the vacuum pipes that operate the power flap in the air cleaner (this should open at 5500rpm and improve the breathing to generate extra power, if this doesn't open power will be down by as much as 80bhp).

2) it's a problem. I haven't done any tests on my car but it looks bad so I must be losing power.

No prizes for guessing my opinion :-)

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Can't you prevent build up by ragging the engine for a good half hour?

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Town driving does seem to choke the engine but a good thrash always cleans it all out and gets it feeling new again. :)

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Too many people buy these types of cars and drive them round like they are shopping carts.. they are designed to be ragged.. they enjoy a good thrash..

My Rs6 was always better after an aggressive drive. The engine was hotter, the map better, the fuel mix better etc etc

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Can't you prevent build up by ragging the engine for a good half hour?

Apparently not. It's not like a buildup in the cylinders, this is the tops of the valves, where the valve stem is.

I'm sure it will affect breathing, the question is if it's to a noticeable degree. The valve tops and lower stems being coated in gunk deposits will interfere with airflow, but does it really matter in an FSI engine? I guess the airflow is tumbled above the valves anyway...

An auxiliary concern is once the buildup gets to a certain size, lumps could break off in the airflow and get into the cylinders, causing premature ignition.

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It's an interesting concept Chris, and i can see where the argument is coming from,

but whether it holds any weight is another thing. Fuel isn't a dirty as it was years ago.. i presume they specify 98 or higher ron.. the valves still get hot and should burn off carbon, as would the fast moving air.. don't forget.. some of these engines at full tilt can use a tennis courts worth of air.

The only way to tell i suppose is to dismantle an engine, but i can't imagine too many owners wanting to do that!

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Fuel isn't a dirty as it was years ago

Oil vapours, from the crankcase breather.

DSCN3443.jpg

IMG_7931.JPG

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Carbon build up issues are no more with the aid of a very simple service with hydrogen technology.

I had mine done, it took 30 mins and she ran like a dream.

Cost £70.00 to remove the carbon build up and left my car with a great increase in performance, power and fuel efficiency.

It ran quieter and smoother.

It cleans the carbon from the air intake right through to the exhaust including turbo's, valves, combustion chamber, inlet manifold etc,DPF(if not too far gone), EGR and CATs...

Very effective, cheap and non invasive service.

 

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The only way to tell i suppose is to dismantle an engine, but i can't imagine too many owners wanting to do that!

As you may know, my 911's engine was dismantled and rebuilt earlier this year. Carbon buildup on the cylinder heads was something they reported, so as I was having everything else done I asked them to clean that as well.

The car always ran on 97 or 98 octane, either V-Power or BP Ultimate. It was regularly thrashed to within an inch of the redline :grin: And the service history was perfect. I think it's just one of those things - I didn't notice any power loss or other symptoms. Mind you, this was after ten years, although only 55k miles.

As for letting someone squirt a highly reactive gas into an engine that wasn't designed to have that, ha ha no chance :roflmao:

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As you may know, my 911's engine was dismantled and rebuilt earlier this year. Carbon buildup on the cylinder heads was something they reported, so as I was having everything else done I asked them to clean that as well.

The car always ran on 97 or 98 octane, either V-Power or BP Ultimate. It was regularly thrashed to within an inch of the redline :grin: And the service history was perfect. I think it's just one of those things - I didn't notice any power loss or other symptoms. Mind you, this was after ten years, although only 55k miles.

As for letting someone squirt a highly reactive gas into an engine that wasn't designed to have that, ha ha no chance :roflmao:

What? you mean like petrol? lmao...

seriously, I love it when people start making out they know it all.... HAHAHAHA AGHHAHAHAHAHA 

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Pardon?  Are you saying hydrogen is chemically the same as petrol?

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What? you mean like petrol? lmao...

seriously, I love it when people start making out they know it all.... HAHAHAHA AGHHAHAHAHAHA

De coke, is that a new word in your world. What do hyrdo carbons leave behind (check you cse chemistry book).

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What? you mean like petrol? lmao...

seriously, I love it when people start making out they know it all.... HAHAHAHA AGHHAHAHAHAHA

Patently wrote he wouldn't let a highly reactive GAS be squirted into his engine - petrol isn't a gas seems you missed that and also that an engine isn't designed to have hydrogen in it. Usually engines are designed to have petrol in them.......

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Oil vapours, from the crankcase breather.DSCN3443.jpgIMG_7931.JPG

There is lots of gossip on MBWorld and the AMG private lounge about this with the m156 (in c63s) and m157 (in e63s) about this and a US company - Weistec have jumped in with a custom catch can for these engines. You might want to ping them about your Audi as the forums do make comment on VAG and BMW cars suffering this blow by buildup more so than the Mercs.

Given the blow by is an emissions compliance thing (burn vented crankcase oil vapour by returning it to the inbox), some folks don't do the catch can, but plumb the bleed into their exhaust to stop the blow by...

YMMV. Decoking a modern engine would be pretty noxious I think.

Edited by Rachel

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a US company - Weistec have jumped in with a custom catch can for these engines.

A few years ago several RS4 owners tried replacing the cyclonic separator and fitting a catch can - it made absolutely no difference to carbon build-up compared to the standard setup.

 

So the evidence suggests that a catch can doesn't solve the underlying cause - which is why current thinking is that it's blow back of combustion products due to valve overlap.

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Catch cans are mandatory on Caterham race engines, as otherwise we leave a trail of black smoke through the corners.

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I thought Chopper was referring to Terraclean?

Doesn't that just use highly refined petrol to clean rather than any other chemicals or gasses?

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As Dave has no doubt spotted, you've posted this exact same message across various Audi forums, digging up 'carbon' related threads from the archives each time.  Flagged yesterday, but post have been left to stand no doubt as your posts don't contain links to services.  Yet....

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he's just a spammer however, as there aren't any active mods on this forum it will be around for a while.

Edited by Andy_Bangle

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