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Thread: choking the pony, or are you?

  1. #11
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    Apr 2012
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    Moose Lake, MN, USA
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    Quote Originally Posted by BigAgCat View Post
    Hehe, people seem to live and breathe pony motors when it comes to these old tractors, but would never treat their pony motor the same way they treat starting the diesel. XD

    It probably would be nice to have some knowledge floating around as far as running the pony motors as what I know is pretty much a result of me just going "I wonder what this does?"
    Look on uTube for Squatch253 and check out his D2 starting video. By far the best one and is the same procedure on any size Cat.
    1937 Cat #11 tandem auto patrol,diesel, w/plow and wing, 6K506SP, 1937 RD 4 Ag Crawler RD5356, 1939 Cat 22 2F5429, 1952 Model 212 Grader 9T03427, 1953 2U D8 Dozer 2U20751, 1961 922A Rubber Tired Loader, 59A812, LeTouneau LS Cable Scraper, Cat/Lincoln 600 AMP Dual Welder, DW-21 Cat Scraper, DW-10 dump wagon/water wagon

  2. #12
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    Apr 2012
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    Quote Originally Posted by Riverina d4 View Post
    My D2 Starting Engine was starting, running and Idling great after a full carby rebuild. But recently became hard to start and un-responsive to throttle adjustment.
    Still doesn't require choke and has loads of power but wont run at low rpm.
    Can anyone help with this?,
    I have removed and cleaned fuel supply lines which were already clean.
    The fuel is fresh and not stale.
    Regards
    Did you remove the lead plugs and use a small drill between the fingers and clean the passages in the carb. Some gas always lays in the lower one at the bottom of the bowl and gunk's up if the pony is not used often. Its usually the cause of bad idle. Soaking never gets it done. If you clean them .177 air gun pellets work good to reseal them. Some tap and insert a small screw for the next time.
    1937 Cat #11 tandem auto patrol,diesel, w/plow and wing, 6K506SP, 1937 RD 4 Ag Crawler RD5356, 1939 Cat 22 2F5429, 1952 Model 212 Grader 9T03427, 1953 2U D8 Dozer 2U20751, 1961 922A Rubber Tired Loader, 59A812, LeTouneau LS Cable Scraper, Cat/Lincoln 600 AMP Dual Welder, DW-21 Cat Scraper, DW-10 dump wagon/water wagon

  3. #13
    Join Date
    Feb 2016
    Location
    southern NSW Australia
    Posts
    114

    Confused

    Quote Originally Posted by old-iron-habit View Post
    Did you remove the lead plugs and use a small drill between the fingers and clean the passages in the carb. Some gas always lays in the lower one at the bottom of the bowl and gunk's up if the pony is not used often. Its usually the cause of bad idle. Soaking never gets it done. If you clean them .177 air gun pellets work good to reseal them. Some tap and insert a small screw for the next time.
    Hi OIH
    yes removed and cleaned all passages. I tapped them 10/32 bolts instead of using the air riffle pellets.
    I'm hoping for a quick fix to avoid removing carb again

  4. #14
    Join Date
    Mar 2020
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    UNITED STATES OF AMERICA
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    It's good to hear from you. fighting!

  5. #15
    Join Date
    Nov 2006
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    Faunsdale, AL USA
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    Your idle jet that admits the fuel into the carb Venturi below the throttle plate may be clogged. Itís a brass plug that has some shallow channels milled into one side of it for the gas to go through. Itís only accessible by driving it through from the right side of the cast iron carburetor INTO the the Venturi. Clean it and the vertical passage down from the idle mixture screw etc and then tap the plug back into place so the grooves are upward to avoid clogging with fine debris. There is a vertical mark on the outer end to make sure you donít get it sideways.

    One other thing to check is that you havenít somehow lost the center ring of the gasket between bowl and Venturi. I think that will prevent one idling but still allow high speed run. If it used to run good but now it doesnít and you havenít had the bowl off, it wonít be that.
    D2-5J's, D6-9U's, D318 and D333 power units, 12E-99E grader, 922B & 944A wheel loaders, D330C generator set, DW20 water tanker and a bunch of Jersey cows to take care of in my spare time

  6. #16
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    Nov 2006
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    I just thought about your statement that itís unresponsive to throttle adjustment. Make sure the extension on the pin through the governor linkage rod fork and crank on throttle shaft is to the left side of the ďfingerĒ on the throttle rod. If this ever slips by the finger, then the throttle cannot restrain the governor to pull the throttle closed so the pony runs at high idle all the time.
    D2-5J's, D6-9U's, D318 and D333 power units, 12E-99E grader, 922B & 944A wheel loaders, D330C generator set, DW20 water tanker and a bunch of Jersey cows to take care of in my spare time

  7. #17
    Join Date
    Nov 2006
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    Pittsford NY
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    cc, I had a different experience to yours for the grooves in the idle jet. I oriented them downwards, below the closed throttle plate, because on my carbs this allows that channel to "see" vacuum and thus pull idle fuel through. After getting a perfect idle with the plug in that position, for grins, I repositioned the plug with the grooves up, above the plate. It would not idle (at least not without jockeying the choke). When I returned it to the down position, it resumed its perfect idle.
    So I wonder if there's some other aspect at play for the idle function. Your comment that the idle jet sits below the throttle plate is probably what it is. When my plates are closed, the edge of the plate bisects the idle jet plug. If your plug is fully below the plate when it's closed, that would explain the difference between your carb and mine. Actually for my two carbs (3J and 5U) and oldparker's (RIP) 5J carb, this has been the case, so I wonder if yours is an outlier in terms of plate position?
    Cheers,
    Neil.

  8. #18
    Join Date
    Feb 2016
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    southern NSW Australia
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    Quote Originally Posted by ccjersey View Post
    Your idle jet that admits the fuel into the carb Venturi below the throttle plate may be clogged. Itís a brass plug that has some shallow channels milled into one side of it for the gas to go through. Itís only accessible by driving it through from the right side of the cast iron carburetor INTO the the Venturi. Clean it and the vertical passage down from the idle mixture screw etc and then tap the plug back into place so the grooves are upward to avoid clogging with fine debris. There is a vertical mark on the outer end to make sure you donít get it sideways.

    One other thing to check is that you havenít somehow lost the center ring of the gasket between bowl and Venturi. I think that will prevent one idling but still allow high speed run. If it used to run good but now it doesnít and you havenít had the bowl off, it wonít be that.
    Hello ccj
    thanks for the advice. I did remove and clean the mentioned idle plug under Neils advice at the time.
    I'm thinking you may be right that it could be blocked. it has also become hard to start.
    will check the pin extension on throttle and report back.
    Thanks

  9. #19
    Join Date
    Feb 2016
    Location
    southern NSW Australia
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    Quote Originally Posted by Riverina d4 View Post
    Hello ccj
    thanks for the advice. I did remove and clean the mentioned idle plug under Neils advice at the time.
    I'm thinking you may be right that it could be blocked. it has also become hard to start.
    will check the pin extension on throttle and report back.
    Thanks
    Pin is set correct to governor linkage.
    Couldn't get pony to fire at all today. Spark is ok. Plugs were dry so not flooding. Starving for fuel somehow I suspect.
    How quickly should the glass bowl at fuel tap on pony tank fill once tap is turned on?. Mine only dribbles in and takes about 10 seconds to fill glass bowl.

  10. #20
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    The ultimate check on fuel flow is to remove the drain plug in carburetor bowl. Should get an initial gush and then it slows down to whatever the whole fuel system can flow. Lots of places for rust and varnish to collect. I would say 10 seconds to fill the sediment bowl is a little slow but at this point I would look on down the line.

    Iím not the expert on the idle jet plug. The recommendation to orient it ďgrooves upĒ is so thereís a space for any small debris to collect behind it instead of clogging the grooves. Possibly a bad idea?

    I think the relationship of the plug grooves to the edge of the throttle plate depends a lot on where the idle speed screw is set. That being said it may not be possible to attain the desired idle speed with the idle speed screw set to hold the plate far enough open to put it in the high vacuum area.
    D2-5J's, D6-9U's, D318 and D333 power units, 12E-99E grader, 922B & 944A wheel loaders, D330C generator set, DW20 water tanker and a bunch of Jersey cows to take care of in my spare time

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