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Ultrasonic Cleaner Fluids

  1. Jan 23, 2017 #1
    I bought an ultrasonic cleaner to clean my fuel injectors.

    It appears very difficult to get a recipie for the liquid to clean in.

    I think using distilled water is best. At about 60 degrees celsius.

    What fluids are good to use?

    I understand that petrol deposits a kind of 'varnish' that can clog up the injectors.

    Acetone, isopropyl alcohol, degreaser are some of the things I've tried.

    Is there an optimal diy mix for various things one might want to clean in an utrasonic cleaner.
    Last edited: Jan 23, 2017
  2. jcsd
  3. Jan 23, 2017 #2


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    I use citranox mixed with deionized water. The proportion is given by the manufacturer.

    But then again, I'm cleaning parts for ultra-high vacuum components, not greasy fuel injectors.

  4. Jan 23, 2017 #3
    Apparently it's "waxy olefins" left from evaporated petrol/gas and "engine heat can bake the olefins to form hard varnish deposits" that need removing from fuel injectors.

    So the cleaner needs to be for that. Preferably something mixed from common ingredients.


    Is distilled water as good as deionised water for this purpose?
  5. Jan 23, 2017 #4


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    If it's wax, you might try paint thinner (or lighter fluid: same thing). If you're really cheap, you could try gasoline, but there might be unwanted additives in there. If it's already at the varnish stage, that likely means the olefins have crosslinked and there's really no great way to dissolve that mess.

    Edit: the hippie in me reminds you to properly dispose of spent chemicals according to local regulations.
  6. Jan 23, 2017 #5
    Thank you. I'll try paint thinners.

    Perhaps the real problem is how to dissolve (or weaken) cross-linked waxy olefin.
  7. Jan 24, 2017 #6
    What is this 'baked on cross-linked olefin, alkene'?
  8. Jan 24, 2017 #7


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    Water doesn't sound right to me. It is not a good solvent for olefins and it can corrode the steel.

    Fuel contains alkenes, which in high temperatures (hence baking) can react producing additional bonds between molecules, we call this cross-linking. What you get in this case is a messy mixture of high molecular mass alkanes/alkenes, which are difficult to dissolve and look like tar.
  9. Jan 24, 2017 #8
    Ok. It never occurred to me that the water might not be a good idea.

    I wonder if whatever success I'm having is due to the presoaking I do with acetone and then running the injectors in a pressure tester with kerosene before and after the ultrasonic cleaning, (where I have tried adding various things to the heated water) and the cavitation process itself rather than the cleaning fluid I'm using.

    I do have some good results.

    Problems are in some injectors leaking under pressure, variable flow rates and poor spray patterns which I've been putting down to wear.

    What is a good option to use rather than a water mix. The ultrasonic cleaner heats the fluid to about 60 C.
  10. Jan 24, 2017 #9


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    Kerosene is basically lighter fluid (slightly different fractions of petroleum distillate).
    Well, then just keep doing whatever gave you those good results.

    It's unclear to me exactly what you're doing. From your first post, I assumed that you'd tried sonicating in acetone, isopropyl, etc. Now it sounds like maybe you're presoaking with acetone and then sonicating in water. If you're worried about putting non-water solvents in your sonicator and you haven't tried it already, you might put your injectors in a container filled with (acetone/kerosene/whatever is working) and place the container in the sonicator.
  11. Jan 24, 2017 #10
    I don't know whether or not the good results I had had much to do with the ultrasonic cleaning and whether or not any baked on varnish was removed. Short of cutting the injectors in half I can't see inside them. (having written that maybe I will cut a rejected one to see).

    It is the ultrasonic cleaning fluid that is of concern, not the presoaking. I have tried adding various fluids to water.

    I'm hoping there is some ingredient (fluid mix (water and? something else?)) that's optimal in at least beginning to loosen up the varnish. (crosslinked olefin / alkenes)

    There are fluids that are sold for use in dirty auto parts that are a water mix, however I understand that these cross linked olefins are 'non pola'r and should be treated with 'non polar solvents' which don't mix with water. ??


    Thank's for the idea of putting the injector in a separate container in the water. That I haven't thought of. Good idea.
  12. Jan 24, 2017 #11


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    "Polar" and "no polar" don't have precisely defined meaning in the context of solvents, it is rather a rule of thumb. Funny how your use of '' fits that :)
  13. Jan 24, 2017 #12
    I put those marks around the 'non polar' to highlight that I don't know what it means.

    Ok. > I can deal with the solvent by putting it in a separate container in the cleaner.

    I think the injector is made from stainless steel encased in a heat and fuel resistant plastic.

    I've tried with no success to find out what the plastic is. I wouldn't want the plastic to be damaged by the solvent. I've had an injector immersed in acetone for a few months so that is ok.

    What solvent for non polar baked on cross linked olefin on stainless steel?

    (I gather from responses that it is difficult to dissolve. I take that to mean it is not impossible.)
  14. Jan 24, 2017 #13


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    Probably detergents. ZapperZ mentioned one above. You can try soap and water. Again, it's all going to depend on how crosslinked the gunk is. But if acetone and kerosene don't take it off, I doubt soap and water will.

    "Impossible" means different things to different people. Polyethylene dissolves in boiling trichlorobenzene, but for all practical purposes, it's impossible without access to a chemistry lab. If the solvents that have been suggested so far don't work, you might be out of luck. From what I can tell, most of the fuel injector cleaners on the market are primarily some sort of petroleum distillate (kerosene, naphtha, etc.)
  15. Jan 24, 2017 #14
    Thank you.


    I'll try suspending a beaker in distilled water. In the beaker I'll put naptha (zippo lighter fluid) and the injector.

    For testing under pressure I'll continue to use kerosene.

    If no objections the purpose of the thread is achieved and much gratitude to all responses.
  16. Jan 29, 2017 #15


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    In my opinion ZapperZ is on the right track. There are similar petroleum based de-greasers that are more aggressive if the citrus based one are not sufficient.

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