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Thread: Gas in oil?

  1. #1
    Jedi Knight
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    Gas in oil?

    I know this thread has been discussed before - I googled the problem - but after I finished my drive the other day I checked the dipstick. The oil looked fine and clear but there was a smell of gasoline on the stick. No leaking from the carbs evident so it might be the fuel pump at long last. Tank is about half full. Two questions:
    1. How do I test the fuel pump for leakage?
    2. TRF sells a pump for $125, Moss for about $35. Your choice? Or - should I just buy a repair kit and re-use the old original pump?

  2. #2
    Obi Wan Rut's Avatar
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    Re: Gas in oil?

    Typically speaking I've seen gas from the carbs, blow by, and leaky fuel pump gaskets cause gas in the oil problems. I eliminated one potential source of gas by going with an electric fuel pump on my TR4a since I've had good luck with them on the Bugeye and MGB. The SUs on the MGB will leak a little after the engine is shut off, but I don't know if this will happen with Strombergs.
    Rut
    Rut, '60 Bugeye, '70 MGB, '62 TR4, '66 TR4a IRS, '67 TR4a IRS, '68 TR4a IRS, '72 TR6

    When I went to school, they asked me what I wanted to be when I grew up. I wrote down 'happy'. They told me I didn't understand the assignment, and I told them they didn't understand life. John Lennon


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    Yoda poolboy's Avatar
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    Re: Gas in oil?

    You may not see any leaks at the carbs, but too much fuel in the float chambers will overflow and drain down the throat of the carb into the manifold, past the intake valve and down into the sump without ever leaving any evidence on the exterior of the carbs..
    Usually the culprit responsible is the float chamber needle valve...
    I'm not discounting hole or split in the fuel pump's diaphragm, which is easy to check; but I believe the carb's float chamber needle valve is more likely...sometimes it clears up on it's own.
    DRIVE 'EM IF YOU GOT 'EM

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    Luke Skywalker trrdster2000's Avatar
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    Re: Gas in oil?

    Putting a fuel line cut off near the last connection at the carbs can help stop this if the cars sets around a lot.
    I use one and is part of the routine shut down now and start up. Open the valve and pump up the fuel.

    Wayne


    '37 MG TA, '49 Triumph Roadster, '70 TR6, 2000 Jaguar XK8, '78 Spit6

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    Yoda poolboy's Avatar
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    Re: Gas in oil?

    Me, too...especially when fuel level in the tank is high.Blue 001.jpg
    DRIVE 'EM IF YOU GOT 'EM

  6. #6
    Jedi Knight
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    Re: Gas in oil?

    It will be hard for me to do a cutoff under the hood. Car sits in the garage almost up against the right wall. I'll never squeeze in to open the hood. The float on carb #1 did stick once many years ago but a smart rap with a wooden screwdriver handle cured the problem and I don't remember any contamination of the oil thereafter.

  7. #7
    Jedi Knight
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    Re: Gas in oil?

    If I take off the fuel pump, where is the leaky part that causes fuel to run into the sump and how do I know it's the culprit? I do have one weak cylinder - I know the rings are bad - so maybe that's the problem?

  8. #8
    Luke Skywalker trrdster2000's Avatar
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    Re: Gas in oil?

    If the rubber layers of the diaphragm are split, that would be the leak at that location. Running down the ventura of the carb is due to a open needle and seat and a little over half a tank of gas, or parking the car nose down hill.
    There is a hole in the bottom of some fuel pumps that will let you know in a hurry you have a leak in that pump. Notice you have to plug the line, well for every gallon of fuel in the tank, about 10 pounds of pressure is on that line, well, not really as it's spread out over a large area, but you get the idea how fast it comes out of the hose if you are not quick enough.

    Wayne


    '37 MG TA, '49 Triumph Roadster, '70 TR6, 2000 Jaguar XK8, '78 Spit6

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    Yoda poolboy's Avatar
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    Re: Gas in oil?

    You will not need to remove the fuel pump in order to examine the diaphragm.....
    Assuming you have an original AC or an AC knockoff, remove the 6 screws in the perimeter, separate the segments and there you are looking at the diaphragm.... If you completely remove the fuel pump from the engine you'll still have to do what I just described in order to see the diaphragm.
    Probably a carb, though.
    DRIVE 'EM IF YOU GOT 'EM

  10. #10
    Jedi Knight
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    Re: Gas in oil?

    Got it. Thanks. I'll tackle the job Saturday and let you all know what I find. BTW, the oil feels and looks ok but the dipstick suspiciously did not go down after a 20 mile drive. Although it's only about a year old with not much driving, I'm going to change the oil anyway. I don't want to wash out a bearing.

  11. #11
    Jedi Knight
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    Re: Gas in oil?

    Fuel pump diaphragm looks fine. No breaks. Used an old trick in taking out and replacing the 6 screws - I magnetized the screwdriver. Pretty hard to squeeze your fingers in there. I also pushed a tray under the car to catch any overflow - there was a bit. About the carb floats, I'm not in the mood to remove 2 Strombergs and bench test them. I'm not so sure there is a real problem since my '02 Honda Accord dipstick had a similar smell. I will change the oil although it looks and feels fine. I'll also rap the float chambers with a big wooden screwdriver handle from my 1956 Irwin square shank screwdriver even though there's no gasoline smell from either carb or in the garage. My wife will be the first to let me know about that...

  12. #12
    Yoda poolboy's Avatar
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    Re: Gas in oil?

    Like I said earlier, if it is a float chamber needle valve sometimes it clears up on it's own....just some debris or even residue left from the evaporation of gasoline within the float chamber that eventually redissolved or got flushed away.
    Setting up a vibration on the walls of the float chamber with your screwdriver is a good idea and related to this technique:
    http://www.6-pack.org/j15/index.php/...t-what-do-i-do
    DRIVE 'EM IF YOU GOT 'EM

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