1950 John Deere model A loss of power.

I am new to the forum and find the information in the posts fascinating. There are a lot of wise and smart people on here and I myself am a newbie so here it goes. I just purchased a 1950 John Deere Model A. It was low on coolant so I added a 50/50 mix until full. I fired the beast up and immediately realized I had a radiator leak. So, I put in two cans of JB Radiator stop leak and she sealed up. I hooked up a three bottom plow on sandy soil and it pulled it like a champ. My operating temperature gauge was not indexed , but sat towards the top of the green. This continued for about an acres time when I noticed my radiator had started leaking. I added about a gallon of water per 30 min and continued working. I noticed a slow decline in power and temperature as well as the day went on until I was in first gear and starting to struggle. My operating temp was barely in the green. I had completed about 3 acres and thought I would check it out in the morning when I had good light.

I fired it up the next morning in which it sounded like a champ but could not pull the plow. I parked it and came back a week later with some ideas. First, I cleaned the air filter in which the oil was creamy. Second, I put in new plugs and checked both plugs for good spark of which it was great. Third,I added about 3/4 a quart of 30 weight oil as it was down that much. Fourth, I added about 4 gallons of water as it had lost that much in the week and fired it up. She ran great but would barely get into the green of the temperature gauge. I added two more cans of JB and crossed my fingers as in the directions it said it works better when running at normal operating temperature. The leak in the radiator did not seal and I could not see any other visible signs of leaking elsewhere. I thought maybe, if I put a light load on it I could get the operating temp up and the JB might work...No power, at least not enough to pull the plow (2" deep) and get the operating temperature up.

My question, is the radiator and hence the operating temperature that crucial in HP performance? I ask only because if that could be the only problem, I can justify spending the $375 on a new core. Thank you for any and all feed back.

I'm not a JD man but some things on engines are pretty much universal.
First of all you don't want to fill the radiator full ti the filler neck. Fill it just above the fins. Otherwise it will just puke the excess back out.
But you did also state that you were down about 4 gallons of coolant. I didn't realize those old 2 poppers even held that much. None of my fords do for sure.
If you are down that much you should easily see where it us leaking - IF it's leaking externally.
Did you check your oil to see if it's leaking into the oil?
Next, is the tractor blowing a lot of white smoke from the exhaust?
If so you could have a bad head gasket.
A compression test is an easy way to find out.
Find where it is leaking. It may be the radiator.
It may not.
Don't just start throwing parts at it.

Don't forget to post on the John Deere forum as there are guys over there who have been working on John Deere As since they were three years old but wouldn't want to come over here and soil themselves. (;>)) The problem I always saw with the newer A (gas burners) was overheating. JD had a water pump kit that helped. Your problem seems to be the opposite. You do have a gas burning A, right? Are you getting the temp from the gauge? Or personal observation?

Thanks for your reply and advice as well. They actually hold upwards of 10 gallons of coolant. There is no white smoke being blown, but I did not dump the oil. When I checked it before starting, it was normal in color but I did not smell it. When I get back to the farm next weekend, it will be the first thing I do. Regarding the radiator, it leaks on the engine side about 2/3 of the way down and I could not see any other visible area leaks.

It wouldn't pull the plow even the next day when cooled down. Starts and runs great.Rules out anything heat related. You have a fuel starvation problem. Start at the tank and work your way down. Probably is in the carb itself. Got worse as you went because the more old dirty gas you run through it the worse it gets. Could be as simple as fill cap not venting properly. Should have a good pencil size flow at carb inlet. I have a nice rebuilt 3 71 for that if you end up needing one. My e-mail is open.

What do you have for compression and have you checked the tappets and valve movement you have problems if it takes that much water.

None of this is particular to JD, just general information to add to what others have said...

Check the governor. With the engine set to full governed RPM (and you verify that it is set to correct RPM), override the throttle at the carb to idle speed. Release the linkage, and observe the throttle does fully open until the engine reaches governed RPM.

Is the choke fully open?

Have you checked the point setting and the ignition timing? If it has a distributor, check the centrifugal advance, and the shaft bushings for wear.

When you serviced the air filter, did you disassemble the upper portion and clean the wire mesh? Might try a test run with the air cleaner hose disconnected to see if it makes a difference.

A long shot, but could the exhaust be restricted? Not very common, but it happens.

The temperature not coming up would typically be a thermostat stuck open or missing, assuming that model has a thermostat... But that would not cause that dramatic a drop in power.

Thanks for all of the responses. As of now, I am going to tackle the following ideas come Saturday morning. Feel free to add to the list if you would like. I will post the results on Monday when I return.
• A disconnect of the air cleaner hose to see if the air flow is obstructed.
• A 1 quart dump of the engine oil as a check for water/coolant.
• A removal of the distributor cap and a point gap check as well as a visual check for wear.
• A fuel supply check to insure proper fuel flow.
• A visual look at the throttle linkage while under load to check if the governor is working. I do not know how to check for governed RPM…
• A compression check.
• A visual inspection of the exhaust pipe.
Thanks again for all of your ideas.

A weekend that turned out better than expected but feeling a little inexperienced.
After an inspection of the radiator, oil, spark plugs, air filter, and fuel supply with no change in performance I adjusted the the clutch. Wow! It grabbed a hold of the three bottom plow and worked like a charm. It was up to operating temperature in no time and to top it off, The JB stop leak sealed the hole in the radiator. It was my lucky day...Thanks for all of the help!

I'm very new and am looking for john deere oneways please call 3087080225 somebody has one somewhere