Gas on the dipstick

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Close, Dec 16, 2018.

  1. Close

    Close Junior Member

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    I checked my oil the other day and smelled gas on the dipstick. Diagnostic at the dealership returned codes p0300, p0301, p0302. They cleared the codes and re-ran swapping coils 1 & 3 and confirmed that cylinder 1 was misfiring. Removed the spark plugs and found them to be cracked from carbon buildup. They also performed a compression check on cylinder 1 @ 129psi. I had them replace the plugs (they were due anyway).

    The dealership has told me that the rings are worn and the engine needs to be replaced. It's a 2005 with ~325,000 miles.

    Any advice on how to keep my car running, without replacing the engine, would be appreciated.

    Thanks
     
    #1 Close, Dec 16, 2018
    Last edited: Dec 16, 2018
  2. M in KC

    M in KC Active Member

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    325K you did awesome! Is the car not running? A fuel odor on the ICE dipstick is generally a indication of a leaky fuel injector or a product of incomplete combustion/misfire (your P030XX codes above). No doubt the unburned fuel cleaned your cylinder walls. If it were mine I would change the oil and filter and go assuming it does in fact run. At this point what do you have to lose. Start squirreling money away for a used engine or your next vehicle.
     
  3. TMR-JWAP

    TMR-JWAP Senior Member

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    Any advice on how to keep my car running, without replacing the engine, would be appreciated.

    Sure. My advice is close to the advice on the above post...now that you have fresh spark plugs, fire it up and roll on. Tell the dealership to kiss off.

    Adjust your oil level to the top (full mark) of the dipstick, check it often and track how much it uses over a 1000 miles or so. Then you just need to figure out if a bit of oil every now and again is better than springing for a replacement engine, which will also probably burn some oil. NO ICE is perfect. They all burn some amount, large or small. The question is what's more financially reasonable?
     
  4. Kevin_Denver

    Kevin_Denver Active Member

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    I question a little bit what the shop is telling you. Did your shop pressure test all cylinders? 129 psi isn't necessarily a bad cylinder unless it's reading lower than the other cylinders. There are a lot of factors that can affect a pressure test reading (temperature, RPM tested at, etc.); reports on here range from 90 to 150 as normal readings. However if 3 cylinders read 150 and one 129 that probably indicates a problem with that cylinder.

    If the oil smells strongly of gas (and not just a little), I would think there's more of a problem with the fuel system than the ignition system. The first place to check for misfires is the ignition system (coils, spark plugs, wires), but the 2nd check is usually the fuel system. A bad fuel injector on a cylinder could certainly cause misfires.

    I always found the oil in my Prius to smell a bit of gas when changing it. Used oil analysis of Prius oil usually show a gas concentration of around 1%. The stop/start cycles leave a little gas in the cylinders that makes its way into the oil. However this gas mostly comes out of the oil and gets burnt through the PCV when the car gets worked for a long period of time (eg. >30 min on highway).

    If it is your piston rings, I would switch up in thickness of oil to a 10W40, which will help the piston rings seal if indeed that is the cause. Also run a tank of fuel injector cleaner.
     
  5. Close

    Close Junior Member

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    Thanks, everyone, for your responses and advice.

    @kevin - they only tested the one cylinder. Their reasoning was that since none of the others were misfiring they didn’t require checking.
     
  6. edthefox5

    edthefox5 Senior Member

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    You will smell fuel on the dipstick. I bought my 07 new and it has always smelled like fuel.
    Another weirdness of the atkisson cycle same with the puddle of oil in the bottom of the throttle body.
    Always there.
    It’s why I always change the oil at 5000 miles.
     
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  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The reason to check all four cylinders is to see if the cylinders are evenly worn. 129 psi might be good, or not, depending upon what the other cylinder pressures are.
     
  8. Kevin_Denver

    Kevin_Denver Active Member

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    I disagree with their reasoning. Okay, if you test one cylinder and it reads 40 psi, it's definitely bad, but a reading of 129psi without testing the other cylinders by itself doesn't indicate a problem. There are a large number of things that can cause a misfire, so this check by itself doesn't tell you that it's a problem with the cylinder holding pressure that's causing the misfire. They may be right or not, but based on the information given, there's not enough to know.

    You could have a lazy mechanic on your hands who based on the fact the engine has 325,000 miles wants to just tell you its worn, when in fact there is some other problem. Misfires can be difficult to diagnose and he or she might not want the bother. Mechanics don't like these kinds of problems because they can replace a number of things and it not get solved, which results in upset customers.
     
    #8 Kevin_Denver, Dec 19, 2018
    Last edited: Dec 19, 2018
  9. wjtracy

    wjtracy Senior Member

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    Gen2 inherently has some fuel in the oil couple percent is pretty normal, so I would not be using an nice oil smell test as the key indicator of engine health. That's why I like to stick with 5W-30 realizing there will be some further dilution.
     
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  10. TMR-JWAP

    TMR-JWAP Senior Member

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    Any gasoline engine would be able to run with 129 psi on a compression check.

    Previous thread about compression checks......

    Compression Test | PriusChat
     
    #10 TMR-JWAP, Dec 19, 2018
    Last edited: Dec 19, 2018
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