carbon mixed with water out of tailpipe at cold start

Discussion in 'Engine Topic' started by pomartin, Oct 17, 2020 at 7:12 PM.

  1. pomartin

    pomartin Member

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    Dear all,

    I have yet another issue I'd need some advice for.
    When the car is cold and started up, there is quite some carbon mixed with condensed water coming out of tailpipe. I'd like to get rid of carbon, I'm getting a bit tired of cleaning garage after every startup :p

    When I bought the car it was running extremely rich, there was a lot of carbon deposits on heads, pistons and tailpipe.
    Now after few thousand miles running with AFR 14-15 when cruising combustion chamber is quite cleaner- carbon seems to be slowly burning up.
    Tail pipes are still black. Valves are nice and clean.
    Operating temperature is about 175f

    Is there any non-mechanical DIY way to clean the carbon up a bit?

    I've read about spraying isopropil-alcohol mixed with water into the carb, but never found good instructions regarding mix % for it.
    Anyone used seafoam or similar?
    How about spraying just pure (de-mineralized) water?
    Or perhaps feeding any of the above through carb vacuum port during load?

    EDIT: engine has a blower if it means anything

    Any tips or tricks are welcome :)
    Thank you in advance,
    Martin
     
    Last edited: Oct 17, 2020 at 7:27 PM
  2. biker

    biker Veteran Member

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    Mine did that too for a while after a bit of a rich spell with the carb. It disappeared once the carb was dialed in. Just could be lots of carbon in the exhaust.

    I've dumped all kinds of stuff into carbs to clean carbon. A gm dealership I worked at in the 80's used to regularly de-carbon engines by dumping water in them. Engine idling, slowly pour water into carb while working the throttle by hand to prevent stalling. Fascinating to see as a kid. Some mechanics would get quite aggressive with it, holding throttle way open and dumping water in, enormous amounts of crap flying out the exhaust. Every single one ran better afterwards though. Apparently the water cools carbon deposits, making them pop off metal surfaces.

    I do not recommend it for an engine you care about though. And I dont know if it would help you since your engine is already pretty clean.
     
    carhead22000 likes this.
  3. Gary S

    Gary S Administrator Lifetime Gold Member

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  4. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    Even with a clean engine... Getting it all out of the exhaust will take time.

    Meanwhile.... Put a big piece of cardboard under the rear of the car to catch the water/soot to keep it off your garage floor.
     
  5. Jodi

    Jodi Veteran Member

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    A nice long spirited drive on the highway with varying load on the engine.
     
  6. muscl car

    muscl car Veteran Member Lifetime Gold Member

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    I still do that de carbon trick but use a spray bottle filled with water . I high idle the engine then spray water into the carb
     
  7. sandlapper

    sandlapper Member

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  8. COPO

    COPO Veteran Member Lifetime Gold Member

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    Go for a drive and hammer it through the gears 5x’s to redline, it’ll clean your plugs and combustion chamber. I use Seafoam in the gas tank and also sprayed it using a sprayer you add air too. As well as Marvel Mystery Oil in the gas tank, just follow the directions per tankful of gas.
    I’ve also used GM Cleens religiously since the 70’s.
    D2F4EA4E-20D9-4146-9216-07359588BC9F.jpeg
     

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