Piston Slap: Bustin' Carbon Down Mexico Way!

Sajeev Mehta
by Sajeev Mehta
piston slap bustin carbon down mexico way

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 sajeev@thetruthaboutcars.com . Spare no details and ask for a speedy resolution if you’re in a hurry.

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5 of 19 comments
  • The Doctor The Doctor on Apr 06, 2012

    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.

  • Deaks2 Deaks2 on Apr 06, 2012

    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.

    • See 2 previous
    • Mrb00st Mrb00st on Apr 08, 2012

      @cacon 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.

  • SCE to AUX This is good news, as long as the Tesla plug can deliver the kind of power needed in the future. I'm not sure that's a settled matter.
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