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Running Diesel fuel through a gas engine?

Discussion in 'The Hokey Ass Message Board' started by xhotrodder, Jan 12, 2010.

  1. xhotrodder
    Joined: Jul 2, 2009
    Posts: 1,390


    For years I have heard by different people, that you can run a small amount of diesel fuel through a gas engine, without hurting it; and you clean out the inside at the same time. Kind of like steam cleaning it. I've always thought it was B.S., but figured I'd post on here and find out for sure. I know there has to be some great mechanics on here. So, what is the truth?
  2. goldhunter_2
    Joined: Jan 10, 2010
    Posts: 81


    I don't know about diesel fuel but we run aircraft fuel through everything now and then to clean it out. I know this works because I can tell the difference on the inside when I do rebuilds the ones who run straight aircraft fuel every couple tanks or a 50/50 mix every now and then are pretty clean pump gas is not. see allot of the bikers and others doing the same , I have put it in my airboat, truck, car, fourwheel, lawnmower and it ain't hurt nothing ........ but diesel I never heard that be interesting to see what is said about it I'll have to watch this thread
  3. hotrod-Linkin
    Joined: Feb 7, 2007
    Posts: 3,382


    you will wash down the cylinder walls and bearing surfaces and ruin a good engine. the gas rings will not stop the diesel from getting into the engine.
  4. A gas-Diesel mix, I could maybe see, with a 20-1 or 30-1 mix, and in a SMALL quantity...but straight Diesel is an absolute no-no. Diesel, kerosene, and Jet-A are very, very close to one another, but gasoline is not.

    I surely would not do it just to "clean things out"!
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  5. Hyway Hauler
    Joined: Aug 31, 2009
    Posts: 670

    Hyway Hauler

    Diesel fuel will not hurt the engine..As far as cleaning it, maybe, but I'm skeptical, because the fact that diesel is oil, and it could end up sludging your engine. I've found the best way to clean the engine innards is to warm up the engine to opperating temp, remove air cleaner, and while throttling up the engine manually with one hand, gradually poor about 1 cup of water...The trick here is to not let the engine stall. The heat of the engine turns the water into steam during combustion, and rids the engine components of carbon deposits on valves and top of pistons. I think diesel fuel will only make the engine run too rich.
    I've also heard of old timers runing a quart of ATF in with the oil, but never tried it because of the lack of lubrication properties in ATF, and the high concentration of detergents...
  6. Rich Rogers
    Joined: Apr 8, 2006
    Posts: 2,019

    Rich Rogers

    I don't know about todays fuels but years ago when I worked at a local store, a guy filled a truck with a gas engine with diesel fuel and ended up calling a wrecker. It dropped dead before it got out of the pump island area
  7. Happy Hooker
    Joined: Sep 16, 2009
    Posts: 39

    Happy Hooker
    from Wyoming

    It would more than likely end up in the oil pan. I realy couldnt see it doing much good.
  8. Hyway Hauler
    Joined: Aug 31, 2009
    Posts: 670

    Hyway Hauler

    The engine will not run too good, but nothing is said before, diesel fuel is simply oil.
  9. LIL.TIMMYUser Name
    Joined: Jan 30, 2009
    Posts: 741

    LIL.TIMMYUser Name

    Ditto running some water through with the revs up. You'll see a big ol' belch of carbon out the pipes. Don't know how effective it is over-all, but it sure blows some crud out.
  10. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,146


    Years ago, a young guy I knew (Gas jockey) was told to run Diesel thru his 289 Ford Mustang by a much older in "replace the oil" and let it idle for a half hour or so to "clean out" the engine.
    He did it and you wouldn't believe how much guck and junk actually came out of the engine when he drained the Diesel out!
    He put on a new filter and refilled with new 10w30 and restarted the now internally spotless engine.
    The first drive was to a chorus of knocks and rattles that hadn't been there before.

    Ultimately the engine was pulled out and sent off to the machine shop for a total rebuild.
    It was a painful and expensive lesson.
    Engine sure was clean though...
  11. Tank
    Joined: Nov 8, 2002
    Posts: 749


    I agree with that, I never put diesel in anything. But cam2 and aircraft fuel, hell yeah.
  12. xhotrodder
    Joined: Jul 2, 2009
    Posts: 1,390


    Thanks for all the information guys. I appreciate it. I knew I could get the right answer on here.
  13. Tank
    Joined: Nov 8, 2002
    Posts: 749


    I had an old guy tell me something VERY similar. He told me to run kerosene at idle for 10-15 minutes. But he told me to run a 50/50 blend with fresh oil. Being young I tried it. Lots of crud came out like you said. Maybe I got lucky, It didnt rattle and clunk when I filled it with fresh oil. Did dirty that oil real quick though.
  14. blitz
    Joined: Jun 15, 2009
    Posts: 139


    i have was told that running diesel through a motor is like trying to start a 2 stroke with starter fluid. pulls oil way from place's its gotta be. i saw the results on a 50 dollar dirtbike wouldent want to see it in a couple thousand dollar motor.
  15. mattybear
    Joined: Nov 19, 2009
    Posts: 69


    I have done the carb trick before but used sea foam. It smoked like a beast for a bit but then ran a lot smoother.
  16. 4tl8ford
    Joined: Sep 1, 2004
    Posts: 1,090

    from Erie, Pa

    I'm an old guy and when I was young had old guys tell me-----
    I've heard of running every thing from av-gas to elephant piss thru an engine to "Clean it out". The only clean engine I've seen after tear down was a Hemi that I ran 115/145 avgas in - not a spot of carbon or crud - not even in the hole thru the top of the piston.
    I ran too much for too long - but the bitch ran hard.
  17. CJ Steak
    Joined: Sep 23, 2008
    Posts: 1,378

    CJ Steak
    from Texas

    If you want a clean combustion chamber, use Sea Foam at the next two oil changes, or do the water trick.
  18. narlee
    Joined: Dec 7, 2009
    Posts: 240


    Don't know about the diesel but water works, it's just a matter of how much. I know it works because of a blown head gasket, it went between a water port and the cylinder. That one cylinder was clean as could be and luckily I didn't hydraulic the piston and bend a rod or something. At one time you could get a kit that would inject water as you drove. It was supposed to prevent detonation and run cooler, good for more compression.
  19. J&JHotrods
    Joined: Oct 22, 2008
    Posts: 536


    ATF does work similar to water when poured through the carb. Smokes like crazy too. I learned the hard way though-many years ago when I was around 15 working at a tire shop, one of the mechanics decided it would be cute to pull a prank on me. I had to go to a different store to pick up some tires and they poured about 1/2 qt. down my carb. when I wasn't looking and laughed as I pulled away, smoke billowing out the exhaust, does an incredible job of burning off carbon deposits. Actually ran a little better once it burned off.
    That being said, let it trickle in, just like using water in the same manner. Do not pour a whole quart in without it running-it will hydra-lock. Ask me how I know............:eek:.
  20. 42hotrod
    Joined: Nov 3, 2005
    Posts: 811

    from S.E. Idaho

    We used to drain the oil out, put a quart of tranny fluid in with 3 or 4 quarts of clean oil before taking the filter off, let them idle a bit then clean em out and change the oil. You wouldn't believe the crap that would come out! forward to today. With the high detergent motor oils out there this would be pointless. If an engine recieves somewhat regular oil changes they stay pretty clean.

    I remember a Pontiac 389 I tore down once. I took the drain plug out and nothing came out. I thought it was empty, but no, the dipstick said it had oil...I stuck a small screwdriver in the drain hole, and GLOP....GLOP...GLOP...pure sludge...that went on for a couple minutes, then finally it started draining. this was a RUNNING ENGINE!! Got the valve covers off, and the sludge was so thick there were impressions dented in the black goo where the valve springs were going up and down. Almost everything else was buried in sludge right up to the rockers. :D
  21. troylee
    Joined: Jul 10, 2007
    Posts: 682

    from Milwaukee

    How about multi fuel tractors and trucks. Like the army 2 1/2 with White engines. You can put anything in those things.
  22. chopolds
    Joined: Oct 22, 2001
    Posts: 5,440

    from howell, nj
    1. Kustom Painters

    That old chestnut of a tale used to be to run it instead of oil, to clean out the crancase, NOT to run it with or instead of gasoline.
    Only time I tried it, I needed to rebuild the engine a few short months later. Could be coincidence, maybe not. It WAS an old, uncared for engine. If you don't watch, it could loosen up all the sludge in the engine, clog up the oil pickup, and lose your oil pressure.
  23. il Revrunde
    Joined: Jun 22, 2005
    Posts: 224

    il Revrunde

    This works but you gotta do it right. Just pouring water in your carb is a sure fire way to jack things up. Use a spray bottle and mist the venturi while at a high idle a few times. thats all you need.;)
  24. SanDiegoJoe
    Joined: Apr 18, 2004
    Posts: 3,520


    I have done it.. In a 250 Chevy. Ran 3 Qts of 30 weight and 2 Qts of diesel. Started it, ran it around the block, drained it and put in 5 Qts of 30 weight.

    It was my dad's idea.

    - Joe
  25. nutajunka
    Joined: Jan 24, 2007
    Posts: 1,466

    from North Indy

    A guy I knew one time went to replace the valve cover gasket on a slant six. It was so full of crude you could barely make out the rockers and such. He asked me what to do and I told him, just put the new gasket on and forget it. He didn't and scraped all that crude loose and poured cleaner in the crankcase and the next day his oil pressure went to 0. Tore the engine down and every bearing was destroyed from all the crude he lossened up.
  26. mbmopar
    Joined: Mar 27, 2006
    Posts: 468

    from Canada

    my buddy used to own a shop, and alot of his customer used to swear by Quaker State, his customers cars all had sludge build up so bad there were impressions left by rocker arms in the valve covers...he swears he would never use the QS and told his customers they could take their cars elsewhere if they wanted to use it after they saw what was inside the engine.....that was early 70`s. this is only second hand info, i have no knowledge of this to prove or disprove it.
  27. ThePuck
    Joined: Apr 9, 2009
    Posts: 116

    from Ottawa

    I have run a 2 stroke gas motor on Jet B in an emergency. It pretty much ruined the motor. The only reason I was able to start and run it was because the motor was already up to temperature on gasoline, and I had to run it on full choke. Oil poured out of the exhaust after a few minutes.
  28. The Hank
    Joined: Mar 18, 2008
    Posts: 779

    The Hank
    from CO

    Pouring stuff in your oil to clean your motor is a BAD idea. All that Marver mystery oil cleaner stuff or what have you. There is a screen in your oil pan that filters the big stiff from your oil.All that crud will plug that screen and oil won't flow and ruin your motor.

    I would be careful with water down the carb, Water does not compress. To much and you could bend a connecting rod.

    The only AVgas I have seen was Lo-lead not no lead so I wouldn't run it in a newer car.It might mess up the converter.

    Avgas is hi octain the stuff I used to buy was lo-lead 100.I was told AVgas burned slow because all plane motors never revved high. I used it in my race Jet Ski's which were 2 strokes,which did revv high.So I mixed it with pump gas.I was to cheap to buy race gas and was running 195 PSI head pressure in my 2 stroke [ time bomb] which is kinda alot for pump gas with a high revv motor. Probably could have got by with 94?

    If it runs good , don't fix it.
  29. Hotrodbuilderny
    Joined: Mar 20, 2009
    Posts: 1,649


    I worked in a Texaco station back in 70 -71, a friend of mines father use to come in
    and drain the oil and filter put 5 quarts of home heating oil [diesel] run for 5 minutes
    drain and put 5qts 30 wt non detergent in it was a 64 impala 6 cyl and he still had it when they moved to Florida around 74 -75 he had done this since the car was new
  30. briggs&strattonChev
    Joined: Feb 20, 2003
    Posts: 2,231


    didnt we have this same lengthy discussion about a month ago? This is the only message board I frequent so idk where else it would have been.

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