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Subject: Starting a rebuilt engine

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Chris Libby    Posted 04-16-2020 at 22:22:37 [URL] [DELETE]        [Reply] [Email]  
  • Starting a rebuilt engine
  • I have restored a 1939 9N*8417* it's pretty original and am excited to start it but...with new 6v battery it is very sluggish, in fact only about 10-15 cranks and the battery can't do any more. Reading some earlier forum posts I tried connecting the 12v battery in my 2011 Acura MDX to the starter only and after a blip of a spark nothing happened. I've tried different grounds to no avail. My tractor starter has just a single connection sticking out of the top-no relay or other connections. I need to get more and livelier cranks to start this thing. Is it the old starter or some circuit protection in my car to prevent the starter from vigorously cranking the engine?

    steveVa    Posted 04-17-2020 at 10:14:42 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Starting a rebuilt engine
  • You want to make a simple loop directly to the starter. I would first add a second nut on to the threaded post that powers the starter. This way you will not damage the threads when you jump to it because you can hit the nut and not the threads.
    Also, I would use a separate battery so you can connect directly to the posts on the 12 volt battery. Connect positive post on battery to tractor frame/ground close to the starter. Make very sure tractor is NOT in gear. Then connect jumper cable to Negative post on battery and then tap other end of jumper cable to post that powers starter. You should get a good spark and starter should bump. Then do the same, but hold Jumper onto starter post to see if it cranks.
    I have heard of folks that have a tight rebuild and have had to pull the tractor when in high gear to get it to spin and loosen up. Make sure you have plenty of oil in everything.
    Good luck. Be safe.

    Dave H    Posted 04-17-2020 at 08:59:47 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Starting a rebuilt engine
  • Did it turn over easily by hand during and after the rebuild?

    John in Mich    Posted 04-17-2020 at 08:01:06 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Starting a rebuilt engine
  • Just had another memory pop up. Are your battery cables new and what gauge are they?
    12v car cables do not work on 6v systems. The cable from the battery to the starter solenoid and from the solenoid to the starter terminal MUST be as big as the diameter of your thumb, the wire NOT including the insulation. Think of a welder cable.

    Tim Daley(MI)    Posted 04-17-2020 at 08:17:39 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Starting a rebuilt engine
  • Good point John about the battery cable sizes that I always forget to add. Also, use a good brand battery, an AG 750 CCA is best, GRP 1 6V and not a gold cart/RV type or a Deep Cycle model. Invest in a float charger (not trickle charger) like the DELTRAN Battery Tender Jr. for maintaining a full charge when tractor is not use. The thing which depletes battery plate effectiveness the fastest is the constant discharging and recharging. Also, remember the 9N and 2N 1-Wire starter motor does not use a solenoid. The solenoid wasn't introduced until the 8N 3-wire model in July, 1947.

    Tim Daley(MI)

    John in Mich    Posted 04-17-2020 at 09:43:11 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Starting a rebuilt engine
  • Solenoid is a bad habit terminology on my part. The mechanical push switch through the case I call a solenoid. Still needs the heavy cables.

    John in Mich    Posted 04-17-2020 at 07:19:00 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Starting a rebuilt engine
  • wow! Your seriel number is 30 older than mine. I have 9N 8047. The engine is out and waiting for me. I have smooth hubs, 32" tires and double rib fenders and a hood with a snap in door to install on it.
    To jump you tractor from a negative ground 12v system: ground your 12v system ground onto the tractor NOT ON THE BATTERY. Take your 12v HOT (positive) and "touch" it to the starter post, do NOT clamp it on. This way, you are only providing 12v to the starter. The starter can handle 12 volts, your 6 volt ignition system cannot.
    If you are trying to start the tractor with this method, turn on the iginition and set the throttle and choke (if needed). DO NOT push the starter button.
    As mentioned, if this does not roll the engine fast, check for ground contact between the starter and the engine block.
    IF the ground is good and with plugs are out to roll it over, it sounds like something is too tight in the rebuild.

    Tim Daley(MI)    Posted 04-17-2020 at 06:07:34 [URL] [DELETE]        [Reply] [Email]  
  • Re: Starting a rebuilt engine

  • HiYa Libby-
    Kudos on your early 9N and restoration project. I’m posting a few 9N wiring diagrams and a LINK to my “Early 9N Generators” in case you don’t already have them. As Bruce said, get your battery verified first. Have it bench tested at your trusty local starter/alternator/generator shop or a reliable auto parts store. Don’t assume a new battery is good out the door. Don’t rely on a basic trickle charger. Verify all wiring before connecting a tested, charged good battery and applying power. Use your VOM set to continuity, not a test light. If you have an exact-as-original wiring harness, color coded wires should be the same as in the diagrams. Also, don’t assume just because you have a 6V battery it is wired correctly for the OEM POS GRN setup. It’s important to know if you have the early 9N 9N-10000-A small generator 7A, 2-Wire/2-Brush, ‘B’ circuit design with an internally grounded Field and externally sourced Field. It also uses the rectangular Voltage Regulator, not the roundcan cutout circuit. FORD soon (after s/n 12500) revised the generator to the 9N-10000-B unit, small, 7A, 1-Wire/3-Brush A-Circuit Design unit the now used the cutout. ALL 9N & 2N tractors (except the 2N warhorse) used the 1-Wire starter motor and NO solenoid. In addition, the circuit uses the OEM Ballast Resistor; the front-mount distributor; the dash-mounted push button starter switch; the dash-mounted ignition key switch; the Ignition “ON” red lamp indicator; and the 30/30 AMP (after s/n 4000) loop-style AMMETER. If you need more help, you can contact me via email –it’s open. Our MANUALS forum has scans of the original MPC’s to download too if you don’t already have them. The March, 1940 MPC was the first 9N manual.




    FORD 9N-10505-B CUTOUT –USED AFTER S/N 12,500 TO S/N 258504 ON 9N & 2N MODELS ONLY:



    Tim Daley(MI)

    Chris Libby    Posted 04-17-2020 at 15:26:38 [URL] [DELETE]        [Reply] [Email]  
  • Re: Starting a rebuilt engine
  • Many thanks to all your comments/suggestions, I will try to comment on all posts here. I believe the engine is very stiff after the rebuild. I have a hand crank and it takes a lot of effort to turn the engine over. I have put about 2 Tbs Marvel Mystery Oil (father in law cure to everything)into each cylinder and tried to get oil in the system at the oil block on back corner of the engine, with marginal success. I have used the heavy battery cables as specified for 6 volt. The positive ground wire is a braided strap. However in my fastidious effort to paint everything I have probably compromised the grounds, I will clean those contact surfaces/bolts up as much as possible. It still does not account for why my 12 volt car battery connected directly to the starter and a cleaned area of the flywheel housing doesn't budge the starter. Unfortunately I don't have a spare stand alone 12 v battery so may need to buy one if this is my only option for spinning the engine. Do the jumper cables need to be as heavy gauge as the 6v battery cables? Not sure where I'd get those. I may try a tow but we are at the bottom of a steep hill with gravel drive and an Acura MDX as a tow vehicle! The electrical diagrams are great. I did reference the diagram with the cut-out (no voltage regulator on this tractor) Thus the generator is a single pole 3 brush, I guess, and of course the distributor/coil is on the engine front. I removed all spark plugs and confirmed there is spark down the line as I cranked the engine. Once or twice the engine has popped enough to kick out the starter but no real sputter. I have also tried starter fluid spray which seemed to get me one or two of the pops. Just not enough speed in the engine turnover to bring it to life. Thanks all and I will try your suggestions as appropriate but please keep your ideas coming.

    Bruce Dorsi    Posted 04-17-2020 at 02:07:36 [URL] [DELETE]        [Reply] [Email]  
  • Re: Starting a rebuilt engine
  • If the rebuild included new paint, you may not have a good ground path from the battery to the starter. ...All connections need to have paint removed where the starter mounts to the engine and where the battery cable attaches to ground, as well as anywhere in between where the current path has been painted.

    Are you trying to crank the engine with the sparkplugs in? ...If so, try removing them to see if that will get the engine spinning easier. ...Put some oil in each cylinder if the engine has been sitting a while since rebuild.

    Was the new battery tested or put on a charger to make sure it was fully charged?

    The tractor should be 6V Positive ground, so the negative terminal powers the starter. ....Your car is 12V Negative ground. ...How are you hooking up the jumper cables?

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