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Thread: Maintenance guidelines makes no mention of addressing carbon buildup / valve cleaning

  1. #1
    Registered Member JPL's Avatar

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    Maintenance guidelines makes no mention of addressing carbon buildup / valve cleaning

    Flipped through the maintenance manual again to see if the schedule called for any such service and it's ignored. Every other thing you can think of is supposed to be checked regularly (some things that usually are of no consequence). Yet, this critical thing to engine longevity gets no mention. Many people will not know that GDI engines need this preventive measure and will be caught off guard when it gets to a breaking point and become an expensive issue.

    I bet this isn't just missing from Mazda's schedules, but likely all other brands. As if OEM's don't want to admit carbon buildup is a reality of direct injection.

    Anyway, there's preventive products you can use and dealer service you can get to prevent a deep dive cleaning down the road (full engine tear down).

    What do you guys think about this?

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  2. #2
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    Nonsense! My local dealership got special formulated magical snake oil to clean the internals of my engine.

    On a serious note. It's impossible to avoid build up but supposedly an oil catch can can slow down the process. Hopefully when I hit 40k to change spark plugs I can peek inside and report good news.

  3. #3
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    SavageGeese's CX 9 review touches up on this. Mazda basically said that the operating conditions of the SkyActiv (higher comp, higher temp/pressure) will mitigate the issue of carbon build up on valves.

    Me personally? I don't particularly care about it. My 07 Speed3 had almost 200k miles when I sold it and I never did a valve cleaning. Sure, maybe lost a few MPGs here and a little power there, but it wasn't worth it to me to do buy the equipment or pay the dealer a few hundred bucks to do it.

  4. #4
    Registered Member JPL's Avatar

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    Good points. I had forgotten Dave Coleman's addressing of this issue (as described in Savagegeese's review).

    I imagine Mazda is confident enough that buildup won't occur, at least in damaging amounts to not make it a maintenance issue. They also sell 100K extended warranties (I got one) with the assumption you won't do any carbon service.
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  5. #5
    Work in Progress sm1ke's Avatar
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    My IS250 was prone to this (though I never experienced any of the symptoms). There was a class-action lawsuit in the US that addressed this, so I would hope that Lexus now details the cleaning service in the manual, but I don't know for sure.

    I think that I'll probably have someone take a look at the valves with a boroscope at 100k (or if I notice any of the symptoms), then do the cleaning if required.

  6. #6
    Registered Member JPL's Avatar

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    I noticed in the dealer service center the usual pamphlets out for numerous services provided. One of them was the BG fuel system cleaning service. So while the owners manual doesn't mention this, the dealer does point out the service option, at least indirectly.
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  7. #7
    Biggie T Skinny helbigtw's Avatar
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    Agreed that this is an issue. I can't speak for direct injection motors, but manufacturers who allow 87 octane to be utilized in the owners manual and then turn a blind eye to carbon buildup are not being honest to the consumer. Acura at least says use premium on all their vehicles, they don't fake it. My 08 CX-9 pings like crazy during cold/warm-up acceleration up a hill. Living in a very hilly area, sometimes can be hard to avoid unless I warm up the vehicle completely before heading out. The only thing that helps it is several tanks of 89 and a bottle or 2 of Seafoam. Those two things help dramatically but then after a period of time the carbon builds right back up again. Likely wouldn't have this issue if I used 89 consistently but in my area 89 is about 75 cents more per gallon. That can make a dent in the pocketbook over time. Even took my CX-9 to a dealer back in the day when it was still under powertrain warranty and conveniently they told me "we can't find anything wrong." But thankfully it is only during warmup and no issue during normal operating temperature.


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