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I had to replace the water pump on my Macan S (68K miles) this past weekend which went well, I ordered a new serpentine belt with the water pump but did not order a new tensioner, luckily my local Porsche dealer price matched the online prices since the bushings on the tensioner we shot. I had everything back together and started the car but I discovered that there was a leak at the cooling vent lines at the right cylinder head. The vent line runs under the intake manifold and Tee's right under the throttle body. Porsche uses a hard plastic tubing which had gotten brittle after only 5 years, I chose to replace the tubing from the tee to the cylinder heads with neoprene tubing which should last more than 5 years. Upon removal of the intake manifold I inspected the intake ports and found that the intake valves in 4 of the 6 intake port had a substantial amount of coked oil on the valve stems. Which is the problem direct port fuel injection, I purchased some throttle body and intake port cleaner which I sprayed at the valve stems and ports. It did a great job of dissolving and loosening up some of the heavy deposits which I was able remove with a plastic scraper. I wiped all the ports with a rag and then used compressed air to remove the rest.

I guess I will probably have to repeat this at 120K.
 

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I think OP said 5 years only.
 

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I’m willing to bet the cooling vent lines is the culprit when people complain about coolant smell. Same issue for years with the cayenne. The buildup on the valves looks pretty common for DI engines.
 

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The Audi 3.0T supercharged engine has the same carbon build-up issues. Some of the forum guys have used solutions ranging from walnut shell blasting, to a chemical cleaner made by CRC. Engine also has a plastic coolant pipe running under the supercharger that gets brittle over time due to heat. VAG minds must think alike, :p
 

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Just as a point of reference, I've seen plenty of carburated engines from the 1960's and '70's that had significant carbon build-up on the intake valves, so this is not exclusively an issue with direct injection engines. There are many factors at play, including the shape and design of the combustion chamber.

I recall one high mileage engine from a '64 VW Beetle that had a pyramid shaped cone of carbon extending from the intake valve seat face to about 3/4" up the stem.

In my experience, mild amounts of carbon buildup should be expected and are not necessarily a concern. Unless we start seeing a history of engines stumbling and throwing codes due to excessive carbon build-up, I wouldn't worry about it.
 

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I owned a '78 BMW 530i and the engine had something called a thermal reactor (Nuke the Whales!),
anyhow, I had the intake manifold walnut shell blasted since it needed the intake manifold gasket replaced.
How did I know? I used engine cleaner and when I was hosing it off, noticed a miss. I then played with
WD40 and water to localize the issue - which turned out to be a leak in the intake manifold gasket.

Water caused the stumble, WD40 caused the idle to increase!

Voila!


Anyway, as SoCalS5 notes, carbon buildup is nothing new...


?

coke - a residue left by other materials (such as petroleum) distilled to dryness


Things go better with...
 

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It's a G
I had to replace the water pump on my Macan S (68K miles) this past weekend which went well, I ordered a new serpentine belt with the water pump but did not order a new tensioner, luckily my local Porsche dealer price matched the online prices since the bushings on the tensioner we shot. I had everything back together and started the car but I discovered that there was a leak at the cooling vent lines at the right cylinder head. The vent line runs under the intake manifold and Tee's right under the throttle body. Porsche uses a hard plastic tubing which had gotten brittle after only 5 years, I chose to replace the tubing from the tee to the cylinder heads with neoprene tubing which should last more than 5 years. Upon removal of the intake manifold I inspected the intake ports and found that the intake valves in 4 of the 6 intake port had a substantial amount of coked oil on the valve stems. Which is the problem direct port fuel injection, I purchased some throttle body and intake port cleaner which I sprayed at the valve stems and ports. It did a great job of dissolving and loosening up some of the heavy deposits which I was able remove with a plastic scraper. I wiped all the ports with a rag and then used compressed air to remove the rest.

I guess I will probably have to repeat this at 120K.
It's a GOLDEN RULE: Always change a tensioner and belt together. Murphy's Law will always get you if you don't......
 

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I have started using Royal Purple Oil on my cars ((S6 and a few S4's B5, B6 and B8.5 also used it on my last Cayenne Techart) and have not had a problem since then. Audi's are notorious for carbon build up and have not had any issues after switching to Royal Purple
 

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I have done so many walnut blasting jobs I couldn’t count at this point. Audi 4.2 FSI V8, a few r56 minis, but the big winner is the VAG 2.0t, same engine as the base macan. It’s not a hard or complicated job. On the 2.0t I have it down to about 3 hours for the job, manifold off, blast, clean, new gaskets, manifold on and drive off. My GTS doesn’t have any signs of bad buildup yet, but I’m sure the day will come. I will take some pics tomorrow of a 2.0t that I have to do tomorrow night for more reference.
 

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Oh and the type of oil really makes no difference what so ever. The oil that is clinging to the valves is the nasty sludge blow by fed back into the intake, and because of direct injection isn’t washed off the valves with gas.
I have had people meticulous with specific top end oils, people who could care less and go to drive through oil change places, and in between. Some might get more mileage than others but it’s going to happen no matter what.
 

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Oh and the type of oil really makes no difference what so ever. The oil that is clinging to the valves is the nasty sludge blow by fed back into the intake, and because of direct injection isn’t washed off the valves with gas.
I have had people meticulous with specific top end oils, people who could care less and go to drive through oil change places, and in between. Some might get more mileage than others but it’s going to happen no matter what.
So gas additives won't work as the gas doesn't go that direction. What is the answer?
 

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So gas additives won't work as the gas doesn't go that direction. What is the answer?
Correct, fuel additives don’t help whatsoever with the carbon build up on valves. And these gimmick spray through the intake, etc might might help the slightest bit temporarily, but they really need to be manually cleaned. I use walnuts shells being blasted at 90 PSI and still have to manually scrape a little bit until they are clean.
 

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This is a pic of the two intake valves on the worst cylinder. This was a 2012 VW CC with 131k miles, last cleaned at 80, so roughly 50k miles and 5000 mile oil change intervals according to the owner.
229904

And this is what I use, blaster, shop vac, and picks with a 3D printed attachment that fits in the head.
229905
 

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This is a 2.0t tsi found in many ve audi and the base macan. For this engine you have to remove the intake manifold, which is just a few vacuum lines, bunch of electrical connections, and the fuel line from the hpfp to the rail. I replace the manifold gasket and throttle body gasket. Some opt to do injectors, replace the manifold itself, plugs, but I always pair this job with an oil change and pcv. I have it down to about 3 hours.
This car had been running poorly for about 3 months when cold, flashing and solid check engine light, and hard to start cold along with misfires.
it had check engine lights for misfires, low idle, intake leak, etc.
When I was changing the oil I noticed oil leaking from between the engine and trans. Once I had it all back together this one wouldn’t run and was still misfiring at idle. I did more diagnosis, and it seems as though now this one will need a rear main seal. It had the original pcv, and either it caused so much suction in the engine that it sucked in the rear main seal or the rear main seal just simply failed. On these 2.0t the rubber seal is glued to a metal plate, and the metal plate is bolted to the block around the crank. The glue eventually fails and causes a leak or the seal completely separated from the metal plate and spins with the crank causing a major oil leak. So now I need to take off the dsg and replace the $50 seal. Dealer charges around $1,000 for this job. It will be around 10-12 hours for me to do this now.
 

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Will a catch can reduce the amount of sludge in our Macans? I had a Weistec catch can ($$$) installed on my old W204 coupe w/AMG Dev Pkg. It collects a lot of oil BEFORE it goes back into the intake. Any input?
 

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