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Technical Gas in oil !!!

Discussion in 'Traditional Hot Rods' started by kyotb8, Aug 13, 2018.

  1. kyotb8
    Joined: Aug 19, 2011
    Posts: 56

    kyotb8
    Member

    Need some ideas on where to start ?? The truck in my avatar is a 39 Plymouth with a 330 desoto hemi. 2 Carter wcfb carbs on an original desoto intake . Engine rebuilt 1200 miles on it . Carbs rebuilt by local “guru” at time. It always puffs black smoke and soot on cold start. I changed the break in oil at 700 miles. It had close to 7 quarts in what should be a 5 quart system.
    Now the oil is up over the full mark by 1/4” or more on dipstick. Strong gas smell when I pull in garage and shut it off.
    Looking for ideas/suggestions on where to start ? Float(s) ? Needle/seat ? New carbs ? Btw the rear plugs get sooty real quick !
    I’m gonna unhook the secondary carb and see if smoke and soot change. Any advice appreciated !


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  2. BJR
    Joined: Mar 11, 2005
    Posts: 5,993

    BJR
    Member

    Bad fuel pump diaphragm will leak oil into the oil pan. Like you stated, carbs.
     
  3. VANDENPLAS
    Joined: Dec 14, 2009
    Posts: 2,019

    VANDENPLAS
    Member

    Sounds like your carbs are rich
    Floats adjusted wrong

    Fuel pump leaking is a good possibility also

    Some times carb builders set the carbs to a base line and once installed you need. To fine tune them

    How is the choke working?
    What kind of air filters are you. Using?
     
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  4. dave89iroc
    Joined: Apr 10, 2018
    Posts: 2

    dave89iroc

    look at the fuel pump, or carbs leaking fuel into engine when not running
     
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  5. kyotb8
    Joined: Aug 19, 2011
    Posts: 56

    kyotb8
    Member

    The fuel pump is a new, not rebuilt,mechanical unit. The air filters are 6" round from speedway. Choke is manual on the primary carb with a cable pull. Choke is open, I think fuel pump works good ?? Cruises ok at 60-70 mph. Sounds like I'll be learning how to set up WCFB'S SOON. The old manual I found on line for WCFB'S goes into detail about adjusting idle mix on both carbs, and setting idle speed with the air bleed screws. BTW, the idle is erratic, I set it at the right speed, and drive awhile, It will be up and want to pull through the brakes ! Guess I look inside the carbs ? What do you guys think ?


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  6. greybeard360
    Joined: Feb 28, 2008
    Posts: 1,392

    greybeard360
    Member

    My money is on the fuel pump. New or not, there is no telling how old it actually is. If it was the carbs, for it to put that much fuel in the oil it would barely want to run. Pull the pump, clean it off and put a hose on the inlet side. Stick the hose into a jar with some gas in it and pump the lever..... don't point the outlet in your direction. If the diaphragm is bad you will get fuel coming out where the lever exits the pump body.
     
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  7. ididntdoit1960
    Joined: Dec 13, 2011
    Posts: 897

    ididntdoit1960
    Member
    from Western MA

    +1 on fuel pump - some pumps (diaphragms) are worse than others with ethanol
     
  8. Hnstray
    Joined: Aug 23, 2009
    Posts: 10,961

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    While the fuel pump is definitely a suspect until carefully examined, a lot of fuel can go by the carbs down through the cylinders and into the pan, commonly referred to as 'oil dilution'. All that black smoke and soot on startup and fouling plugs strongly suggest you have serious carb problems.......

    Ray
     
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  9. Jalopy Joker
    Joined: Sep 3, 2006
    Posts: 23,944

    Jalopy Joker
    Member

    x2 - be very careful when draining oil from motor that has gas in oil - friend working on a customers car was laying under car had drain pan to catch (regular) oil - using a standard bulb drop light - removed drain plug and oil/gas shot out and hit light - Fire!! - lucky for him a friend happened to drop by just then and helped him get out from under car - had piece of rug under car which helped oil from moving any further - car had a major damage - shop some surface damage - be careful
     
  10. suspect fuel pump and then carb floats and needle valve & seats. And its rare but a flat exhaust lobe on the cam will let gas into the oil.
     
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  11. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 5,802

    Bandit Billy
    ALLIANCE MEMBER

    Ill jump on the fuel pump band wagon. I had the same problem with a completely different set up. 3 97's on a blown flatty. I knocked the fuel pressure down to 3 pounds with a Holley 12-804 regulator and had it power tuned. No more issues. Don't wash those cylinder walls, stop driving it until you fix it.
     
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  12. porknbeaner
    Joined: Sep 12, 2003
    Posts: 41,384

    porknbeaner
    Member

    You are either flooding it or if you have a mechanical pump it is leaking past the diaphragm.

    Here is a quick story. I was reading and article that was based on in interview with TV Tommy once. It was mentioned that at one time he was running an injected Buick mill inn his T. He said that he went to carbs because with the injected mill he had to change the oil every time he fired it up. The injectors were dumping a lot of fuel and fouling his oil.
     
  13. carbking
    Joined: Dec 20, 2008
    Posts: 2,592

    carbking
    Member

    If the carbs are responsible for a 2-quart addition to the oil in 1200 miles, you haven't been seeing anything out of the rear-view mirror!

    My guess would be more than one issue (sooty plugs), but think the fuel pump is probably the culprit for the fuel in the oil. Have had it happen to me.

    When you figure it out, remember to change the oil AND FILTER at least twice!

    Jon.
     
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  14. Gas in the oil Can turn your engine into a bomb. When your crankcase getto wipping that gas around and it vaporizes all it takes is one spark and you get a explosion. I seen a 318 dodge blow the valve covers off. The old caterpillar D7 had a 2 cyl gas pony engine that bolted to the side of the main diesel engines block. You started the pony engine and crawled up on the track and worked a couple of levers to engage a pinion and clutch. That turned over the main diesel and started it. This guy filled the pony gas tank full and started the dozer and flipped the switch to kill the magneto on the pony engine. During the day that gas all made is way past the needle valve and past the pistons into the pony engine crankcase. The next day He went to start the cat. The pony was out of gas. So he filled the tank and fired up the pony engine, And was on that track working the levers when the pony engine blew apart. It sent cast iron shrapnel flying. injured the guy pretty badly. My old cats the pony engines gas tanks always leaked. I poured a pop bottle full of gas in them to start them every time. Then turned off the valve at the settlement bulb and let the ponys carb run out of fuel to kill it.
     
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  15. kyotb8
    Joined: Aug 19, 2011
    Posts: 56

    kyotb8
    Member

    Thanks to everyone for the info ! I Never realized the fuel pump could leak like that ! I'll test it, and then look into the carbs. Thanks again.


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  16. Hollywood-East
    Joined: Mar 13, 2008
    Posts: 1,054

    Hollywood-East
    Member

    Definitely get a fuel psi reading! Those carbs are about 3-4 ish, I doubt it's your pump, Due to the fact it's collecting in the back cylinders, Think about it.. Your engine has a couple degrees of tilt, gas liquid going to lowest cylinders
     
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  17. kyotb8
    Joined: Aug 19, 2011
    Posts: 56

    kyotb8
    Member

    Any one have a link to a service manual for WCFB carbs I could look at on line ? Float settings, ETC ???


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  18. It sounds like you may have more than a couple issues to deal with here. :mad: Try not to get too "zoned-in" on just a carb problem or just a fuel pump problem. This kind of troubleshooting can be a hair pulling experience. If possible, try to concentrate on one area at a time while also keeping an open mind to all the other potential contributing factors. :confused: Don't get so distracted by all the suggestions here that it keeps you from focusing on one issue at a time. ;)
     
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  19. 1934coupe
    Joined: Feb 22, 2007
    Posts: 3,513

    1934coupe
    Member

    As had been said before, change your oil. Gas in the oil plays hell on the bearings.

    Pat
     
  20. 40Standard
    Joined: Jul 30, 2005
    Posts: 5,749

    40Standard
    Member
    from Indy

    I had the same problem, it was the fuel pump
     
  21. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 4,841

    Ebbsspeed
    ALLIANCE MEMBER

    Plug the outlet for this test. That puts maximum pressure on the diaphragm. If there is no pressure and the leak in the diaphragm is small, you may not see any gasoline coming out of the lever opening. Plugging the outlet will force fuel through the diaphragm if it is bad.
     
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  22. porknbeaner
    Joined: Sep 12, 2003
    Posts: 41,384

    porknbeaner
    Member

    I changed a GMC V six in an old school bus because the diaphragm cracked and let gas into the crank case. The guy driving it didn't notice until it gave up the ghost. If he had been watching his oil pressure that fact that the pressure dropped dramatically would have clued him that something was wrong. Fro whatever reason he didn't notice until the clattering got really loud and the old jimmy wouldn't pull an old sick woman off a bed pan. Bad news bears man.
     
  23. Mr48chev
    Joined: Dec 28, 2007
    Posts: 26,092

    Mr48chev
    ALLIANCE MEMBER

    Years ago I saw an engine that had swelled out valve covers and oil pan in a friend's shop where he was working on it for a customer and he said the fuel pump had leaked gas into the pan and a small explosion had happened in the process. He was doing a rebuild on it including turning the crank because it had had gas in the oil long enough to wipe out a journal on the crank.
     
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  24. Truck64
    Joined: Oct 18, 2015
    Posts: 3,853

    Truck64
    Member
    from Ioway

    That's good stuff there. Another way that might be quicker, is disconnect the inlet side and connect a vacuum gauge. Start the engine and let it idle till the vacuum comes up, should rise to say 10" or so maybe. Stop the engine and pump should hold the vacuum and not leak down.
     
  25. Hollywood-East
    Joined: Mar 13, 2008
    Posts: 1,054

    Hollywood-East
    Member

    I get the fuel pump issue, been there done that, First thing I replace when starting anything that has sat, If you guys would read the OP, He is getting soot/rear plugs loaded up.... So gas in oil only loads up rear/firewall plugs....? Come on... smh, Are your throttle shaft's damp, dripping? After running? Dead ring'r Rite there... Fuel psi reading??
     
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  26. Truck64
    Joined: Oct 18, 2015
    Posts: 3,853

    Truck64
    Member
    from Ioway

    That's crazy talk!
     
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  27. 54vicky
    Joined: Dec 13, 2011
    Posts: 1,221

    54vicky
    Member

    the pump is a good source for fuel in oil.the problem once isolated to pump will be finding a pump that is built in NA with so much shit from a foreign country.also a pressure gauge in line to carbs will be a good investment again no offshore shit.hopefully you caught it in time as already stated the damage can be very expensive to repair fingers crossed for you
     

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