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just wondering.

Discussion in '1982-Present GM Diesel' started by eightyone, Nov 8, 2005.

  1. eightyone

    eightyone 1/2 ton status

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    is it true that glow plugs are only there to help start a diesel? and some motors dont even have em? i read that on http://auto.howstuffworks.com/diesel.htm , and thought it was pretty interesting. thanks.
     
  2. 6.2 man

    6.2 man 1/2 ton status Premium Member

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    Yep , thats right most of your big rig motors don't use them .
     
  3. diesel4me

    diesel4me 1 ton status Premium Member

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    weirdness!...

    Yeah,I've seen some "semi-diesel" engines by Hercules and Waukesha ,that use spark plugs and a coil to fire them up,like a gas motor!..I guess once its running it shuts the spark off somehow. :confused: .they dont have the 23:1 compression like a "true" diesel..but run on diesel fuel!..

    The detroit diesel in an old Trojan forkloader that was at the junkyard I worked at had some kind of weird magneto ignition instead of glowplugs.. :confused: that thing would start by jumping it off ONE car battery,even if the motor barely turned over!..even in cold weather..We never messed around with it,because it always started an ran good--didn't have too!.. :crazy:
     
  4. arveetek

    arveetek 1/2 ton status

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    Yes, you're right. Glow plugs are only needed to help start a cold engine. On our GM diesels, the plugs are turned on for a few seconds until they glow bright red. When the engine is turned over, fuel is squirted onto the plug where the hot tip ignites the fuel. One the engine is running, there is enough heat held in the block from previous combustion and from high compression that the fuel is ignited simply by being injection into the hot combustion chamber. If the engine is in good shape, glow plugs won't be needed to restart a warm engine.

    Some diesels, like the Cummins 5.9L used in Dodge trucks, don't use glow plugs, but use an intake heater to heat up the incoming air, resulting in the same thing. Other diesels use an Ether injection system, which works really well because Ether ignites at a much lower temperature than diesel fuel. And still other diesels, like the larger over the road truck engines and medium duty engines like the 6-71 Detroit or DT466 international have no starting aids whatsoever. The higher compression and higher pressure fuel systems allow them to start in cold weather with no problem.

    Casey
     
  5. arveetek

    arveetek 1/2 ton status

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    Actually, I 've seen and read about smaller 4 and 6 cylinder engines like that used in some antique tractors from the 1930's. Had both a carburetor and an injection pump. Started on gasoline using the spark plugs, then switched over to diesel running on the injection pump. Pretty strange animals.

    Casey
     
  6. diesel4me

    diesel4me 1 ton status Premium Member

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    Exactly!..

    Yep--my dad worked in propane gas plants,supervising LNG unloading and distribution...thats where I saw the Waukesha and Hercules motors...they also had a HUGE diesel as big as a 10 wheel dump truck that powered a compressor to send the LNG to all the mains and to the customers houses..looked like the ones on a Navy ship!.. its maximum speed was about 600 rpm!:eek1:

    I saw some weird diesels in locomotives too,that resembled those model airplane engines,only on steroids!--pistons nearly 3' in diameter,and they had a huge single glow plug,(or maybe a spark plug??) in the center of the head!..two cylinders,1500 hp!--they coupled 5 or more of them together to pull long trains...

    I've seen old tractors that were "dual fuel",that could start on gas,and then switch over to diesel or kerosene once they warmed up!..but they were not diesel engines..even seen a few old Briggs and Stratton's the same way--had two cas caps on the fuel tank,and two fuel lines and shutoff valves..there is some weird stuff out there in the engine world... :crazy:
     
  7. imiceman44

    imiceman44 1 ton status

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    Yep my Perkins 5.9l turbo diesel doesn't use glow plugs, and it starts fine all the time with just one battery, even when we were stuck in the snow overnight with snow all over my engine it still took half a revolution to start at midnight.
    :D
    IceMan
     

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