More MD questions

I looked again today at an MD maybe to buy. Starter has been fixed and has new 12 volt battery. took 3 plugs out put lever in gas-start position and cranked her over. Put my thumb in sparkplug holes I could reach. IT seems to crank slowly for a new battery, but is in a very cold barn and has 40 wt. oil in it. Seems to have fairly good compression, but don't know precisely how much. Mag has no spark, even after filing points, so I would think points, condenser, and maybe coil would need replacement. Starting tank leaks, but can be fixed.
Don't know about carb yet, but no external damage.
This tractor has not been run on the gas side for a long time. Present owner pull started it with shot of ether, but I want it to run correctly. I will find out tomorrow how/if it runs as we will pull it. IF it runs good, is that a clue as to how the valves are??? I'm somewhat on the fence as to whether to buy it or not, as I'm new to MDs. Any comments or suggestions would be highly appreciated. Sorry for long post.

On the right side of the engine in behind the carburator is a rod that needs to be in the total up position to start. Sometimes the flipper on the intake doesn't go all the way up thus not allowing spark and not allowing the gas valves to open enough.

I"ve had my M diesel for almost eight years now and finished the restoration in June 2005. I love the tractor since the complete engine overhaul it has lots of reserve torque and is very very efficient on fuel. The engine runs at 75% load for 10-12 hours on less than six gallons of diesel. Back to your potential tractor before starting check the oil in the injection pump, there is a petcock for this purpose on the pump itself about an inch up from the bottom. You don"t want any diesel fuel in the oil, if there is the pump plunger is most likely worn. There are a few other causes for the fuel in the oil to. That oil is supposed to be changed at the same time as the engine oil. Scavanging pump in the injection pump could be worn or plugged, or the return stand pipe in tank could be cracked. Also check for excessive diesel in the engine crankcase oil. Once the engine starts it should run on all four cylinders within a minute or less, if it is missing on one or more cylinders the engine will puff white smoke everytime the missed cylinder goes through the exhaust stroke. If the engine continues to puff white smoke (miss) on one or more cylinders the missing cylinder has low compression. Caused either by bad rings, leaking valves, or faulty injector. If the engine has execessive blow by from the crankcase vent tube bad rings are indicated, the starting valves can be checked by with the engine running on diesel cycle carefully loosen the spark plugs and check for excessive leakage. If you can"t determine which cylinder is missing, if any, with the hood removed you can slightly loosen the bleed screws on the injectors one at a time till you locate the injector that least affects engine operation, this does the same as pulling plug wires on a gas engine. One word of caution though on loosening the bleed ports, stand to the left on the injector your testing, as the fuel will spray to the right under high pressure. As with any engine check for oil leaks, coolant leaks, oil pressure, temperature, coolant level and condition, also check the fuel pressure gauge on the injection pump if the engine is running poorly. The gauge should be in the white range at above half throttle, if it isn"t the fuel system isn"t getting the fuel it needs, either clogged fuel filters, water trap screen, or intake pipe in bottom of fuel tank. Also if the engine is running poorly check for the air cleaner inlet tube being clogged, as diesels require huge amounts of air to run properly. You may also not be getting a spark due to the magneto cut off switch located in the front end of the intake manifold, on the diesel cycle the switch grounds the magneto to prolong plug life, you can disconnect this wire at the mag and check again. The mag is the same as the other letter series EXCEPT it turns counterclockwise. I hope this helps with your concerns, or questions. If you have any other questions you can also email me directly.

Ditto on the mag cutout. I washed my '49 MD and screwed this part up. There must have been some important oily goo keeping things working right
What are the additional causes for crankcase oil dilution? A lot of folks told me it was the lift pump, but they were wrong. I had that rebuilt and after reinstalling it is no better.
I would like to add one additonal thing. Keep in mind that carb parts are not the easiest to come by for these tractors. My bowl was spiderwebbed and I had a somewhat difficult time finding a replacement. IIRC there wasn't a full rebuild kit available either. Just certain parts. (But I know a lot more now than back in 2004 so I may have not known where to look)
When I bled the injectors it didn't spray out of 2 and 3, just dribble. I am sure this is a cause for dilution, but the system does get air into the water trap when sitting (IIRC it didn't do this until I replaced the lift pump) Sorry to the OP for the hijack, I can certainly start a new thread if you would like.