Diesel M?

Sat Oct 20, 2007 6:53 am

I know this is off topic and should be moved. There is a M out on E-Bay http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... =p3907.m29 that is a gas starting diesel. Is this a true diesel or just an engine that starts on gas and then changes to diesel, as the old kerosene burners did?

Sat Oct 20, 2007 7:04 am

The MD was a true diesel. Those early gas-start diesels were really something in their day.

Sat Oct 20, 2007 7:12 am

Big Hoss, I don't know much about the M diesels, But when I was a little boy my grandfather had an IH bulldozer that started on gas after it warm up some what you would move an lever to run it on diesel. It was a true diesel engine. I think it had 3 valves per cyl. & one of the was a starting valve for gas, been a long time. maybe someone elese will chime in here. Dave F.

Sat Oct 20, 2007 7:32 am

We sold an IH crawler this summer. We also sold a MD. With the MD, you swapped fuels with a lever. The Crawler auto swapped on it's own. The Crawler was a 1936. My father-in-law loved to collect and actually used most of his collection during his lifetime.
The family has been on the farm since the 1880's.

Sat Oct 20, 2007 7:33 am

that one says it does start on gas .

Sat Oct 20, 2007 6:10 pm

An MD is a gas engine and a deisel engine in the same block. The head has three valves per cylinder. An intake, an exhaust and a decompression valve that opens an extra chamber in the head to lower the compression ratio so running on gas doesn't blow the head off.
When starting the injection pump is left in the off position so no deisel fuel is delivered to the cylinders and the the decompression lever is pulled to open the extra valve which also opens a slide in the intake manifold which opens to the carburator. The same lever also turns on the magneto. Pull the choke, crank the starter and you're away. The engine must run on gasoline for a couple of minutes to warm the engine, then in one quick motion you push the decompression lever and pull on the desiel fuel throttle and with a bark and belch of black smoke she's running on deisel (if the engine was warmed up enough :) ).
When shutting off you shut down the injector pump and pull the decompression lever to let the engine cool down a few minutes on gas so the head doesn't crack.

Sat Oct 20, 2007 6:57 pm

Parts Man has it dead on. We have a '50 MD, and I'll tell ya I love that thing. Some people choose to shut them down on gas cause they say it is too hard to restart. I have always shut ours down running on diesel. After I'm done plowing or discing I let it idle for about 10-15 minutes or so and the temp is back down where it should be with no load and then shut it down. Restarts are no problem.

I'll also add that these things are torque monsters, and work very well being lugged. They're rated at 31 drawbar HP. Last month I plowed about 2 acres under that was all rough sod. I used a 3 bottom 14 inch Oliver trailer plow. They weigh in at about 5860 lbs. Right now I have ours at about 6300 lbs. It went all day on about 5 gallons. Another nice thing about ours I like is it has an M&W clutch on it. Great tractors they are. But then again, it is a Farmall, that's to be expected.:D

Doug

Sun Oct 21, 2007 12:17 pm

I recently sold a '41 MD that I had for 10 years. I liked the gas start diesel's, but decided to get rid of her. One big problem is you can get into big money when working on the motor. Also, the little valves liked to warp, so it is good practice, if you shut off on gas, to pull the lever back to switch it over to diesel. This would close the little valves. Also as mentioned before, notorious for cracking heads.