By on April 5, 2012


TTAC commentator cacon writes:

Hello Sajeev,

I’m a long time reader, but not much of a poster. Anyway, I currently own a 2009 SEAT Leon (bought new, I’m from Mexico if you wonder how I got this car), which is basically a 5th gen VW Golf in drag, 1.8 TSI engine and 6 speed manual, 32k km in the odometer (about 20k miles) almost 100% of city stop and go traffic. Currently, there’s nothing wrong with the car, but today I took it to the dealership for the vehicle emissions tests (all good) and looking at all the services that they provide I found this: Engine Carbon Build Up Cleaning with Hydrogen, so I ask the service representative what it was, in he basically told me that a machine is connected to the fuel system of the car and they feed it with hydrogen and keep the car running for about half an hour, and that should remove all the carbon build ups in the system.

Reading this and other forums I learned about the propensity of major carbon build in the valves, regarding the direct injected engines, so I found this interesting. Googling this cleaning system, I rapidly found about it: OxyHydrogen Engine Carbon Cleaning, although I just barely read about using it in scooter engines.

Then it came to me!! Ask Master Sajeev about it!! So I’m wondering if you ever heard of this system and if it’s really effective in removing carbon build ups, or if it is a bad idea to ever think about it. Dealership charges about $50 to perform this service by the way….

Saludos desde México!!

Sajeev answers:

Yes, these systems are real and they can be valuable to remove carbon buildup.  But it begs these questions:

Are they better than an $8 bottle of Seafoam? Compared to Seafoam, these services are self-contained, so all the nasty carbon build up isn’t blown out the tailpipe. And that’s certainly a good thing for your neighbors! Definitely worth the extra money spent, especially if you live in an urban area.

What about water instead of Seafoam? All we are talking about is hydrogen and oxygen busting carbon off of metal parts, chemistry says that regular H2O should work fine. In very small amounts, of course.  I don’t have the nerve to verify that yet, but the Internet says water works perfectly. And that probably accounts for something.

Does a late-model vehicle really need it? Not usually, as only older vehicles spend enough time on the road to build up carbon in detrimental amounts. The exception is today’s direct injection motors, as they are known to choke up with carbon far quicker than a traditional port-injection setup.  And I am sure the Leon has the same direct injected 1.8L Turbo of other VAG products, which means that a not-entirely closed injector can drop fuel into the combustion chamber upon shutting down the motor.

If your car has performance problems, either when you drive or when someone (or the computer) tests for emissions, de-carboning the system is a great idea in direct injected motors.  It might beat the crushed walnut shell treatment previously mentioned.

Do you really need it? That’s the final question.  If you drive hard enough to kiss redline on the tach a few times a month, I’d be surprised if you have any carbon buildup in your SEAT’s motor. If you barely drive faster than 20mph and never use more than half throttle, you might need it.

But I seriously doubt you do, so I’d pass on any sort of carbon-busting treatment.

Send your queries to [email protected] . Spare no details and ask for a speedy resolution if you’re in a hurry.

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19 Comments on “Piston Slap: Bustin’ Carbon Down Mexico Way!...”

  • avatar

    From what I can tell, this has rapidly become the favored dealership service department upsell/bogus service. In a DI engine, it might be necessary after the vehicle accumulates some serious mileage, but for normal engines in a late-model car it’s boat-payment material.

  • avatar

    My 98 TL has a C32 V6 and they’re known for carbon building up in the EGR. I had it cleaned by my Honda mechanic and asked the best way to keep carbon from building up, run it through the RPMs at least once a week…which I do when accelerating on the interstate.

    • 0 avatar

      FYI it’s a J32.

      The J32/J30A1 had an absolutely horrendous EGR ducting system. You basically will need to remove the intake manifold and clean the EGR port every 50k miles if you want optimal fuel economy and save the life of the EGR valve. There is a Honda TSB which recommends drilling out the port a little bit and inserting a little copper tube; I think the kit sells for like $14.

    • 0 avatar

      Saw the same thing on my 97 CL coupe with the F22 4-cylinder…only it took until 200k until the CEL finally threw the “EGR insufficient flow” code.

  • avatar

    I have to ask this: with direct injection no longer spraying raw fuel at the intake valve stem, how is adding anything to the fuel going to clean carbon out of this area?

    The carbon buildup issue became very real to me since I recently lost my 1996 Civic engine because of this (my best guess – intake valve sticking open when car parked overnight) and I can no longer even start the engine to try to do any kind of treatment to it (lost one cylinder first, then parked a few days, now won’t even start). Fortunately I have a replacement engine waiting to be installed.

  • avatar

    Water…? Cannot be compressed so it essentially increases the compression ratio. Water was used by the Germans in WW2 to boost the power of some their fighter planes but I believe was dropped due to exploding engines.
    Red line the engine now and then or take the car for a nice long highway trip once in a while.
    Any car will get carbon build up in heavy, low revving, slow driving city / traffic use.

    • 0 avatar

      The compressibility of water has nothing to do with it.

      Water injection (usually water-methanol mix to prevent freezing) cools the combustion chamber and prevents knock.

    • 0 avatar

      What Sajeev is talking about is the shade-tree mechanic’s trick of dribbling water (usually from a glass Coke bottle) into the carburetor while holding the throttle open (engine running of course). This was a very inexpensive way to clean the carbon out of the cylinders (followed by an italian tune-up out on the highway afterwards to blow everything out, often followed by cleaning of the spark plugs with a grit blaster).

      Ahhhh, the good ol’ days! When one could fix a car with a coke bottle full of water and some bailing wire . . .

  • avatar

    I can’t speak Spanish, so I wonder just what the ad pictured is really trying to say. I don’t quite see the appeal of steering wheel mounted airbags punching you in the face…

    • 0 avatar

      It’s basically saying some repair shops use inferior, aftermarket parts that may not perform as intended, and encourages the reader to take their Seat to an authorized Seat service department.

      It’s been a long time since high school Spanish, but that’s what I got from it.

    • 0 avatar

      What Banger said is correct, here’s a complete translation:

      “Without genuine spare parts it doesn’t works the same

      Better use SEAT spare parts and guarantee the optimal functioning of your car”

  • avatar
    The Doctor

    Apparently the only thing that Seafoam doesn’t do is cure baldness. I’ve yet to see any before and after photos of Seafoam actually removing carbon buildup that aren’t from the company itself.

  • avatar

    As the owner of a 2011 GTI with the 2.0 TSI, I can assure you that the back of the intake valves get coated in crap because of a poor PCV system. Tracking the car makes it even worse as oil is drawn up the PCV, further gumming things up and causing oil starvation if you don’t top up.

    Seafoam once a year or removing the intake manifold are good ways to fix it. There is documented evidence showing that leaving this unchecked leads to major power losses. Audi will cover any cleaning on the RS4 engines which also suffer from this.

    The next generation TSI is supposed to have a Toyota style dual injection system with DI and port injection. Those engines should no longer have this issue.

    • 0 avatar

      I once rad about the process of seafoaming it, at the time it didn’t seem to be very straightforward but I’ll take a second look. I prefer to spend 50 bucks cleaning it, than to have to disassemble the whole engine head and clean the freaking valves.

      • 0 avatar
        bumpy ii

        I thought it was fairly simple. Start the car and let it run at a steady 2,000 rpm (I propped a stick between the seat and gas pedal). Pull the vacuum hose off of the brake booster and stick a small funnel in it. Dribble Seafoam down that hose until the engine starts to bog, stop dribbling and let the engine catch up, repeat for a few minutes, then dump a big chug down the funnel to stall the engine. Put everything back in place and let it sit for an hour or so, then start the car up and drive around vigorously (lots of acceleration bursts) until it stops billowing vast clouds of smoke from the tailpipe.

      • 0 avatar

        I would recommend NOT bogging the motor to the point of stalling out when seafoaming, you could hydrolock it and bend a rod. After all seafoam is a liquid.

        it’s really a two person job.

        Person 1: sits in the cabin and modulates the throttle, holding it around 2k rpm and applying more pressure when the seafoam goes in to compensate for the load

        Person 2: finds a vacuum line that pulls air INTO the intake manifold. Get a small glass or something, pour some seafoam into it, and slowly suck it through the vacuum line- basically skim off the top of the surface, being careful not to bury the line in the fluid and choke the motor out.

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