"dieseling" '75 d200 345

Discussion in 'General IH Tech' started by ihscoutmatt, Mar 6, 2012.


  1. ihscoutmatt

    ihscoutmatt High Wheeler

    Joined:
    Jun 2, 2002
    Messages:
    1,446
    Likes Received:
    8
    Trophy Points:
    38
    Location:
    Donaldson Ar
    My '75 D200 diesels really bad after I shut it off, after some research on the web I read that this is caused by unburnt fuel burning after its shut off is this true? if it is how do i fix it, its got a shot holley 2210 carb on it that Im already planning on replacing should I look for some hotter spark plugs Im running autolite 303s I would really appreciate any help with this its really embarrassing to pull up some where and shut it off and it keeps running for a few seconds
     
  2. 76 xlc

    76 xlc Banned

    Joined:
    Feb 7, 2011
    Messages:
    618
    Likes Received:
    1
    Trophy Points:
    0
    Location:
    Wickenburg, AZ
    Could be idle set too high, timing off or vacuum leak making idle fast.

    What kind of temps are you seeing?
     
  3. FMhouse

    FMhouse Farmall Cub

    Joined:
    Sep 10, 2011
    Messages:
    95
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    manitoba
    try advancing the timing and reducing the idle speed...switching from ported to manifold vacuum on the spark advance can help.
     
  4. IH64Scout

    IH64Scout Dreams of Cub Cadets

    Joined:
    Apr 13, 2004
    Messages:
    4,683
    Likes Received:
    16
    Trophy Points:
    38
    Location:
    Jessup,PA
    i'm sure it's not the problem, but the correct plug is a autolite 85.
     
  5. BO185

    BO185 Y-Block King

    Joined:
    Jun 8, 2004
    Messages:
    3,449
    Likes Received:
    189
    Trophy Points:
    63
    Location:
    Jacksonville, Arkansas
    Matt my 392 in my travelette would do it in the Summer on a hot day. But its getting a TBI when I get home. So that will take care of it!:D

    I'll let you know how the TBI works out.
     
  6. Jay Tabor

    Jay Tabor Banned

    Joined:
    Jan 2, 2002
    Messages:
    4,716
    Likes Received:
    6
    Trophy Points:
    0
    Location:
    Pahrump, Nevada
    how can it be sparkplugs? didnt you turn the ignition off?
    how can it be timing? didnt you turn the ignition off?


    too much fuel getting into intake manifold and cylinders is USUALLY the cause.
    so ----- carb is leaking fuel, and or idle speed is way too fast.
     
  7. BO185

    BO185 Y-Block King

    Joined:
    Jun 8, 2004
    Messages:
    3,449
    Likes Received:
    189
    Trophy Points:
    63
    Location:
    Jacksonville, Arkansas

    http://en.wikipedia.org/wiki/Dieseling



    The timing can cause it as well as high idle as others have mentioned. Check out the wikipedia link.

    Granted wilipedia is not the end all rule for information but pretty good none the less!
     
  8. Jay Tabor

    Jay Tabor Banned

    Joined:
    Jan 2, 2002
    Messages:
    4,716
    Likes Received:
    6
    Trophy Points:
    0
    Location:
    Pahrump, Nevada
    thats what you get for referring to wikileaks..
    so you want to get wikileaks to explain how ignition timing makes a gas engine start dieseling,
    WHEN THE IGNITION SWITCH IS TURNED OFF, and the coil isnt making anymore electricity, and the dist isnt sending it to a sparkplug???????????????????
    maybe when the ig. switch is turned off, the dist turns backwards and the coil fires anyhow? and makes the engine run backwards?
    its a magneto, right?
    or-
    maybe the alternator and battery decide they dont want the engine to stop right then, and keep sending volts to the coil and dist, and that confuses the dist and it sends volts to the cylinders at the wrong time and so the engine acts all funny and makes noises?

    magic perhaps?
    i see that all the time in houses, turn off the lights at the switch and they turn on again ..


    ask wikileaks for an answer..
     
  9. hacri

    hacri Farmall Cub

    Joined:
    Sep 25, 2005
    Messages:
    123
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Eugeniesgt
    Bad gas can chause dieseling. Volvo used 2 have that problem in the 70/80's era. People used 87 oktane gas. They started to use a shut off valve on all their cars to cure this problem. I think the valve was on the idle circuit of the carburator. But they said 98 oktane gas would cure it.
     
  10. ihscoutmatt

    ihscoutmatt High Wheeler

    Joined:
    Jun 2, 2002
    Messages:
    1,446
    Likes Received:
    8
    Trophy Points:
    38
    Location:
    Donaldson Ar
    thanks for the info everybody, Ive been planning on changing the carburetor in the near future anyway and that looks like the most likely cause
     
  11. Scoutboy55

    Scoutboy55 Farmall Cub

    Joined:
    Jan 3, 2005
    Messages:
    224
    Likes Received:
    64
    Trophy Points:
    28
    Location:
    Monrovia, CA
    The "run-on" condition being described is caused by something in the combustion chamber that is still hot enough to touch off a combustion event. The momentum of the crank and all of the pistons continues for a revolution or so after the actual ignition has been cut. A carb will not shut off fuel, so as the engine winds down, its still sucking in a useable mixture. A spark plug (or exhaust valve, or carbon booger, etc.) that's still red hot can touch off that mixture and continue the combustion cycle. If more than one cylinder has that going on, you get the "dieseling" he's talking about.
    This sounds like a new problem, so lower quality gas is the first thing that comes to mind. Higher octane is less likely to combust without a spark. Try some better gas and see if that helps.
    Next would be the idle speed at the time of ignition shut-down. If its low, the engine won't have the momentum to carry through very many compression cycles, and the engine will die. If the idle is high because the timing has been bumped forward, then there may also be some pre-ignition (pinging) causing the chambers to heat-up beyond a "normal" level. This is what I described above.
    The big question is "What's changed?" to suddenly cause this issue. This problem doesn't just happen by itself. In the mean time, shut it off in Drive. That normally cures it.
     
  12. 76 xlc

    76 xlc Banned

    Joined:
    Feb 7, 2011
    Messages:
    618
    Likes Received:
    1
    Trophy Points:
    0
    Location:
    Wickenburg, AZ
    Because timing affects operating temps?

    Agree fuel introduced into overly hot cylinders can ignite.
     
  13. Jay Tabor

    Jay Tabor Banned

    Joined:
    Jan 2, 2002
    Messages:
    4,716
    Likes Received:
    6
    Trophy Points:
    0
    Location:
    Pahrump, Nevada
    late timing- maybe-secondary cause.. because the piston is half way to timbuktu when the spark occurs,
    so a cylinders walls will be hotter.. raising coolant cyls. temps. causing carbone to glow in the dark.
    most noticeable by pinging/really bad running /poor performance/ detonation while engine is running at speed >>>>>>>>>>>before shut off.
    however late timing means low rpms at idle speed, if engine /carb not tuned properly.



    advanced timing- engine runs cooler-less cylinder wall exposed to combustion heat while engine is running.so that negates that being a cause.
    however with poor gas grade octane- more likely detonation occuring- with advanced timing, which will raise the comb. chamber temps.
    back to bad tune/carb adjustments


    but thats all secondary- its still too much fuel in combustion chamber when engine shut off-
    because of high idle speed and fuel suck.
    so- its really the vehicles owners fault, not timing..
    after all --this cause and affect was learned back in the late 1800's
    and here it is 2012,?? same group still hasnt learned.
    do schools not teach automotive repair anymore>?
    are all the books burnt?
    was there a gap or skip in education?
    this gets discussed every week . .
     
  14. ihscoutmatt

    ihscoutmatt High Wheeler

    Joined:
    Jun 2, 2002
    Messages:
    1,446
    Likes Received:
    8
    Trophy Points:
    38
    Location:
    Donaldson Ar
    I'll try running higher octane gas Ive been running 87

    the truck has a holley 2210 on it that although its been rebuilt still isnt quite right

    Ive had the truck since June and its done it the whole time Ive had it, since Ive had it, the carb has been rebuilt, I changed the dist cap, rotor, plugs, plug wires and points and condenser next is going to be changing the pos carb to a holley 2300
     
  15. Jay Tabor

    Jay Tabor Banned

    Joined:
    Jan 2, 2002
    Messages:
    4,716
    Likes Received:
    6
    Trophy Points:
    0
    Location:
    Pahrump, Nevada
    lower the idle speed
     
  16. Scoutboy55

    Scoutboy55 Farmall Cub

    Joined:
    Jan 3, 2005
    Messages:
    224
    Likes Received:
    64
    Trophy Points:
    28
    Location:
    Monrovia, CA
    X2

    I thought we were talking about a new problem. If the ignition gack you've replaced looked bad and/or caused the truck to run poorly, then that's probably a good move. But if the truck was running decent and you replaced those parts to cure the run-on, you've zigged when you should have zagged. Like Jay says, too much fuel, too much RPM at shut-down.
    You'll need to get the thing dialed in with idle speed, idle mixture, and base timing. 87 octane should be fine if its a stock motor. There are plenty of threads on dealing with those basics. But in a nutshell, you need to gain access to a vacuum gauge and a timing light. Adjust the mixture screws to get the highest vacuum reading you can. Then adjust the curb idle back down (it likely went up) to 700-750 (Park). Then go to the timing. Cap or pinch off the vacuum advance hose and put the initial timing to 10-12 BTDC. Normal up the advance hose, and readjust the idle again. Then go through the idle mixture once more. That should get you close. If it doesn't ping under load, you can try creeping the timing up, couple degrees at a time. Don't over do it.
    None of this will help though if you have a vacuum leak. So before you do anything, go through all of the hoses and make sure they're not leaking and are going where they should. You don't want anything uncapped on the carb. I don't know your skill level, so if you've done all of this, don't take it the wrong way. Just pointing you down the most logical path. Let us know how it goes.
     
  17. scorp1us

    scorp1us High Wheeler

    Joined:
    Jul 28, 2009
    Messages:
    1,495
    Likes Received:
    2
    Trophy Points:
    38
    Location:
    Baltimore, MD
    Check that your cooling system is working properly.

    You do need a tune-up. Both timing and fuel will effect your temps, but I am fairly sure you have run-on because your cylinders are getting too hot.

    If it was idle speed then it shouldn't run on when you shut it off in drive, as that will bring down your RPMs. as others have said, with a mechanical fuel pump and alternator, you can run-on forever. (But you won't, eventually your cylinder temps would drop so run-on would cease)

    Usually run-on comes from running too lean.
     
  18. Doc Stewart

    Doc Stewart Content Team Staff Member Moderator

    Joined:
    Jun 6, 2003
    Messages:
    8,593
    Likes Received:
    43
    Trophy Points:
    36
    Location:
    San Francisco, CA 94066
    Higher octane fuel does not solve anything but does cost more.

    If you are still having the problem after following all the good advice above, you may have excess carbon in the combustion chamber. To remedy that, get your engine up to operating temperature and set the idle at about 1500 RPM, With the engine running, slowly pour a pint of water into the carb a little at a time. The engine will bog down [if it stalls, you poured too much]. Allow it to get back up to the fast idle and pour a little more until you get the entire pint through the engine. Set your idle back to normal and you are good to go.

    Do this OUTSIDE! you will be creating lots of steam and smoke.
     
  19. FMhouse

    FMhouse Farmall Cub

    Joined:
    Sep 10, 2011
    Messages:
    95
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    manitoba
    Hi Jay I guess you deserve an explaination of how incorrect or retarded timing can cause run-on.The reason is that if the timing is retarded,a larger throttle opening is required for a given idle speed,and as well the residual temperature in the combustion chamber is higher,these conditions are condusive to run-on or "dieseling".If the timing is advanced,the idle speed picks up,and this allows the throttle opening to be reduced,lowering the available air and fuel in the engine when it is turned off.Remember that on most all engines made starting in the 70's,the stock tuning settings were for emissions and not performance or driveability.Many engines can be re-tuned for better performance and mileage,the stock settings are not always the best.Switching from ported to manifold spark vacuum allows the timing to advance at idle and this is one technique that can be used to eliminate run-on.
     
  20. BO185

    BO185 Y-Block King

    Joined:
    Jun 8, 2004
    Messages:
    3,449
    Likes Received:
    189
    Trophy Points:
    63
    Location:
    Jacksonville, Arkansas
    I have done this with Seafoam as well smoke like a mother! I always want to do it a couple times and pull the heads and inspect to see if it actually works.:cornfused:
     

Share This Page