JohnW

Thanks for the thoughts, all. You've made me think of a few other things we did, that I missed in the OP. This has been on/off over a couple months, so hard to recall every last thing we've tried at one time or another. Matt K: Compression was checked warm, not necessarily "hot". 1000 RPM for ~10 minutes, then pulled the plugs quickly, and checked. As for oil, the original owner was the brother of the Ford/NH dealer in Linn, MO (at that time). He told us he was using Ford/NH 15W-40 in it. Dad decided to continue that, and that's what's in it to this day. Basically the equivalent of No. 1 15W-40. We also bore scoped the cylinders - very little carbon on top the pistons, cylinder walls look nice. No cross hatching still visible, but no vertical scratches/lines, either. Diesel Doctor, you do make a great point on saving it with the choke. However, that does not work every time. When it doesn't, it usually needs to sit for half an hour to restart. When it does work, you can choke it hard enough to make it puff a bit of dark (rich condition) smoke. On three occasions, as soon as it died, we immediately jumped off and pulled the carb bowl drain plug as quickly as we could. Steady, heavy flow of gas for up to several minutes, which would be through the needle and seat. Have also blown back through the fuel line multiple times. We have inspected inside the tank with a very powerful LED light on several occasions. There is nothing floating around, and we have had the sediment bowl screen out of it since we started using the inline filters. We have loosened the fuel cap, and gave it a thorough cleaning. It's the IH triple baffle replacement safety cap, btw. I am more confident than ever we are now down to an ignition or electrical issue. If an ignition problem, one would think that changing the resistor/coil/condenser would have some effect (beyond just delaying). Hard to believe a brand new component would have the exact same failure mode/point as the one it replaced, but certainly not impossible. Neither coil heats up excessively, btw. Of course they mount to the cylinder head, so they get too warm to hang onto, but not hot enough to burn you upon touch. I've seen a failing coil get hot enough to cook most of the paint off itself. Have thought of installing a Pertronix electronic ignition kit, but would rather not (yet). Exercise those brains, guys. Someone will have that "Eureka!" moment.

I never thought that I would be unable to make a mechanically sound C200 run, but here we are. Looking for other ideas beyond what we have already done. 1971 Farmall 544, gas, gear drive. 6400 hours total, very original. Was my dad's tractor, he bought it in 1993, so 32 years in the family and counting. He was unable to do anything with it after about 2019 (he passed away at 94 in 2022), and it sat indoors from then until this past spring. He was an IH/Case-IH dealer tech, and it was maintained very well. We expected fuel system challenges, from gas evaporating and the tank sitting dry for so long. It was always a very smooth, strong running machine, and we did not expect significant issues otherwise. Basic condition is this: It will cold start and run very well, basically just like it always did. Anywhere from 15 - 25 minutes after startup (depending on how hard you pull it) it will suddenly die out, with almost no warning. You may be able to unload it (PTO off, clutch in) and save it by throttling way back, maybe some choke. You can sometimes then limp it back to the shop right away (with a lot of random misfire), or sometimes have to wait until it cools down half an hour or more. We cannot get it past this. Initially, we focused on fuel. Original Marvel Schebler carb, with anti-dieseling solenoid. New anti dieseling solenoid to replace a leaking original (done prior to the current issues), confirmed working properly both installed and out of the carb. Yes the screw-in metering orifice was installed in the new solenoid. Carb disassembled (total of four times, iirc) confirmed to be clean, including idle jet/passage, inside of bowl, and inlet fitting screen. Float level set properly, needle and seat in good condition, no excess play in throttle shaft. Inline fuel filter installed in line between sediment bowl and carb. Have swapped in fresh ones several times. Confirmed plenty of fuel flow to carb, and out of bottom of bowl, including when it has died and will not restart. As a final check, we pulled the identical carb off the C200 in my 574 and swapped it onto the 544. No change (and the 574 runs great with its carb back on it). We also looked into ignition issues as we eliminated fuel concerns. Replaced original key switch - worn out, unreliable contact. Delco distributor with clip-on cap - cap and ignition wires (copper core wires, not suppression core) in good condition. breaker points near new, no corrosion, gapped .020", confirmed with dwell meter. Replaced condenser with new, old stock replacement from Case-IH. Replaced original coil with new 12V coil marked for use with external resistor. Original ballast resistor measured a bit high, so replaced it. Coil receives 12V while cranking, ~8V while running. Was running as low as 5.6V across coil with original ballast resistor. Will now throw a spark 1/4"+ easily. Replaced Autolite 3116 plugs that looked great with a new set of Autolite 3116 plugs. Checked timing, found it retarded by ~4-5°. Set it to 0° at low idle, confirmed that mechanical advance pulls it up to ~22° advanced at WOT. (IH specs 0° at low idle, 20° at WOT) New coil and ballast resistor made it feel a little stronger, and prolonged the time until it dies out by a few minutes, but did not solve the main problem. Also looked into the mechanical health of the engine. Compression: 150 - 155 psi across all 4 cylinders. All reach 145 psi on three revolutions. Manifold gasket was replaced ~2017, very few hours since then. Retorqued all manifold bolts, no intake or exhaust leaks detectable, hot or cold. Checked valve clearances. Five of them at .025" to .027", three a bit loose at .031". All set to .026"-.027", per IH spec. The only other mechanical health check I can think of is cylinder leakdown, but I would have to get a leakdown tester. Seems like a real long shot given the compression numbers. None of this long list of items has affected the main issue of it dying out, other than to delay it a bit. We are fresh out of ideas, and can't think of anything we have missed. Hopefully you guys can.