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Gas in crankcase oil

Discussion in 'Gearheads' started by fubarjohnnyr, Jan 13, 2018.

  1. fubarjohnnyr

    fubarjohnnyr Sharpshooter

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    My son has an old '94 Caprice Classic with a 4.3L L99 V8 engine. He states there is gas in the oil, anyone got some recommendations as to what I should be looking for here? Stuck injectors, bad pressure regulator, or otherwise?
     
  2. CHenry

    CHenry Sharpshooter

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    Injectors will be the culprit.
     
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  3. KOPBET

    KOPBET Sharpshooter

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    How much gas? Noticeable level change or just smells? How long since last oil change?

    Any other symptoms? Check engine, black smoke, hard start, sputtering, high mileage? Anything?

    You can borrow tools from many parts stores. I would check easy things first. Get a fuel pressure gauge, check pressure while cranking and how long it takes to bleed off. Check cylinder compression and leak down, compare cylinders. Are any or all plugs wet?

    Oh, and change the oil.
     
  4. fubarjohnnyr

    fubarjohnnyr Sharpshooter

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    I haven't personally inspected it yet, but oil change done about 600 miles ago. From what he has told me, noticeable level change on dipstick.
     
  5. MacFromOK

    MacFromOK Sharpshooter

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    If it has a mechanical fuel pump on the block, the diaphragm is probably busted.

    If so, replace fuel pump and change oil & filter.

    This is dangerous btw. I saw a Ford engine once that had fired in the crankcase and blew off both valve covers and the oil pan.
     
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  6. Snake

    Snake Sharpshooter

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    Surprised it hasn't thinned out the oil enough to spin a bearing.
     
  7. Oklahomabassin

    Oklahomabassin Sharpshooter

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    Hopefully it's not fubar Johnny.
     
    Last edited: Jan 22, 2018
  8. swampratt

    swampratt Sharpshooter

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    I have ran gasoline in the oil many times to super clean an engine and never hurt it.
    That is a long story though.
    First engine was 200inline 6 ford.
    300,000 miles on it and fuel pump went out .
    Noticed fuel level was dropping and engine was running really rough and then I smelled gasoline.

    Filled it up so full it was coming out of the dipstick.

    The next couple oil changes were really clean and the car ran much better.

    Seems to have cleaned the rings I suppose.
    With that in mind I used a mix of gasoline and trans fluid to clean a couple bad oil burners.

    The deal with some oil burners is the oil rings are stuck from all the varnish and goo.
    Couple ways to un stick them..remove and clean them or make a solvent bath inside the crankcase/ oil pan.
    Oil that is in it mixed with transfluid and diesel or gasoline or mineral spirits or toss in some berryman an some laquer thinner.
    Many solvents you can use.. but you need oil in there to keep it lubed

    Cold Engine : start the engine rev it up shut it down.. maybe 6 seconds run time.
    Let it set 20 minutes and repeat.

    You should have about 2.5 gallons in the crankcase of a 5 quart system.
    This cold start splash solvent bath will get solvents on the rings and loosen the varnish.

    I repeat this about 6 times during the day never let engine warm up.. as this will evaporate the solvent and it will not work.
    Next morning do the cold start rev thing and let set 20 minutes and do it again 1 more time.
    Drain the concoction in the evening and fill with good oil and change filter. drive around the block and change oil and filter again.
    after a couple days of driving you can change oil and filter 1 last time.


    I have done this to some of those mosquito foggers you see going down the road.
    Fixed many of them..Yes they were my salvage yard auction purchased fogger vehicles.

    I can't drive it like they were. so might as well try it.
    Does not work for bad valve seals/guides.

    Remove O2 sensors before doing this if the car has them.

    Nitromethane is what is very hard on bearings when it gets into the oil castor oil helps that situation.
    gasoline is not something I worry about especially with other lubricants in the engine.
     
  9. fubarjohnnyr

    fubarjohnnyr Sharpshooter

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    Diaphragm on the fuel pressure regulator wasn't busted, no gas getting into the vacuum there. Replaced the injectors on Saturday, so far that appears to be the culprit but we'll see in the next few days. Engine runs damn sight better too.

    Swampratt, it for sure scrubbed the internals. After the oil change, it's hard to see the new oil on the stick from it being so clean.
     
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  10. MacFromOK

    MacFromOK Sharpshooter

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    FWIW, that wasn't what I meant.

    Engines used to have a mechanical fuel pump mounted on the side of the block that was powered by the camshaft. Sometimes the diaphram would rupture, and allow fuel to be pumped (or siphoned with the engine off) directly into the crankcase.

    Hopefully you found the problem, just keep an eye on it for a few days. :drunk2:
     

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