Dan Newberry
Member
I've owned two 8n tractors for the last 4 to 5 years. Over that time, I've studied and worked on these things... and gone through the gamut of finding every time I'd go back to use either one of them, something would be wrong, they wouldn't start. I have learned a lot, and I've learned it "out of sequence" as I didn't read enough, and/or didn't listen well enough to what experts here and elsewhere had told me.
So... if I were to run into a guy who had just bought on old 8n to work on for the purposes of using it, I would advise them this way (please feel free to disagree with and correct me here where I'm wrong, or overlooking something).
1. Pull the hood off the tractor. Remove the gas tank and steam clean the tank out, or at least pressure wash the tank. Both of my tractors had all kinds of gunk in the tanks. Some kind of gray slime (whatever that is) was in both of them. Pressure wash the tank until it's clean. If it's rusty, you can clean it with muriatic acid. A clean tank is *super* important or you're going to find that you keep having carburetor problems. Dry the tank well (blow it out with an air hose if you have one). At the very least, let it air out well so there will be no water in there. If your tank is really bad, get a new one.
2. While the hood is off for tank cleaning, check the compression on all four cylinders. You will need to buy or borrow a gauge for this. If you have less than 90 psi on any or all cylinders, you're going to need to do something about that. An overhaul could be in order. If you don't want to overhaul the engine, you might test engine Restore, a product that helps seal old rings. (see youtube "project farm" he actually tested the product and it worked amazingly well in the long term on a diesel engine in a Ford tractor). Use that at your own risk, but if you don't have good compression there isn't much point in continuing with reviving the tractor for use.
3. I've found that you can get a carburetor off ebay for 60 dollars, delivered. No kidding. And they work extremely well. Yeah, it's not the original. Overhaul the original and keep it of course, but for a working tractor the knock-off carbs for sixty bucks will get you going quick, and cheap. They're aluminum, so they don't rust.
4. Switch the tractor over to a 12 volt system if you want to work the tractor. I did try to go original with a 6v system on my 52 8n (my 48 had been converted when I got it)... but I couldn't get it to start well. I did put the good, heavy cables on it and still couldn't get reliable starting. The battery was new too, from Tractor Supply. I think it's much easier to get good spark with a 12v system. You can get the 12 volt conversion kit on Amazon, eBay, or other places. (note: if all else is in good order, the 6v system probably will work fine, but it's easier to maintain the 12v system, I believe)...
5. Realize that just because you're getting spark, that doesn't mean the spark is hot enough to start the tractor. This fact came to me pretty late, after I had racked my brain over and over... the info is here in the archives, multiple times... but I hadn't seen it. If you're getting fuel, and getting spark, but not getting the tractor to start--it could be that a jump start from another 12 volt vehicle will make the tractor start. If the starter is taking so much of the battery's power that there isn't enough left to run the coil for a good spark, the engine won't start. The spark may well be there... but if available power is being mostly gobbled up by the starter, the spark voltage may not be hot enough to ignite the gas.
6. Always shut the tractor off by shutting the fuel off at the sediment bowl. Let it run until it quits, then turn off the key. This will keep the carburetor clean. The needle valve and seat on the Marvel Schleber carb doesn't always stop the flow...
7. To start the tractor, it might be best to turn the fuel on for about 10 seconds, then turn it off. Don't use the choke too much, as this will cause the engine to flood... spark plugs get wet with gas and even ether (starting fluid) won't get it to hit (that's been my experience). If you don't get the engine to start after about 5 seconds of cranking, "blip" the choke for a second at most, and see if that helps. If you pull the choke and crank on the engine over-and-over... it'll almost certainly flood. This is bad for your plugs, and even worse for your engine oil as the raw gas will run into the crank case.
8. Get a test light, 12volt if you're on a 12 volt system. Ground one end (battery - terminal or frame, test to be sure you have a light by touching the probe to the + battery terminal, and you're ready to test)... You should have power across both terminals of the amp meter on the dash board, and on one terminal of the key switch in the "off" position. When the key is on, you should have 12v on both sides of the terminal. The switched side of the key switch goes to the coil. Be sure you have voltage on the coil with the key on. Don't leave the key on long, because if the points in the distributor are touching or near touching, arcing could ruin the points. If you have voltage going to the coil, but still no spark, your problem is either the coil itself, or coil/plug wires... or the points in the distributor. There are tutorials here and elsewhere that will help with this. With the front distributor tractors which are used up until 1950 (I believe) the coil can fail most easily, so keep an extra on hand. Be sure you order the 12volt version if you've converted to 12v, that is.
9. There is a resistor on the inside of the dashboard that has about a 1 ohm value. You should be reading voltage on *both* sides of this resistor when the key is on. If you have voltage (test light comes on) on one side of that resistor block, but not the other, the resistor is bad. For my 1952 tractor which has the standard automotive 12 volt ignition coil, I did not use a resistor. Fir the front mounted distributor models, I am told it is best to use that resistor. They are not expensive.
10. There is no overflow tank for the cooling system. You need to leave about 3 inches of room at the top of the radiator so hot water/anti-freeze can have somewhere to expand to. You're supposed to fill the radiator only until the cooling coils are covered in the tank. If you have over-filled your radiator, you will get "boil over" and you'll think something is wrong, when there may be nothing wrong. But be sure you keep the fan belt at proper tension, or it will not spin the fan well enough to cool the radiator.
I'm sure there are other things, but if I had seen a list like this 2 years ago maybe I'd have had a lot less trouble. I'm still learning. I'm sure there are list out there which have been compiled by wiser folks than me, but there is my list. Hope this can help someone somewhere down the road.
So... if I were to run into a guy who had just bought on old 8n to work on for the purposes of using it, I would advise them this way (please feel free to disagree with and correct me here where I'm wrong, or overlooking something).
1. Pull the hood off the tractor. Remove the gas tank and steam clean the tank out, or at least pressure wash the tank. Both of my tractors had all kinds of gunk in the tanks. Some kind of gray slime (whatever that is) was in both of them. Pressure wash the tank until it's clean. If it's rusty, you can clean it with muriatic acid. A clean tank is *super* important or you're going to find that you keep having carburetor problems. Dry the tank well (blow it out with an air hose if you have one). At the very least, let it air out well so there will be no water in there. If your tank is really bad, get a new one.
2. While the hood is off for tank cleaning, check the compression on all four cylinders. You will need to buy or borrow a gauge for this. If you have less than 90 psi on any or all cylinders, you're going to need to do something about that. An overhaul could be in order. If you don't want to overhaul the engine, you might test engine Restore, a product that helps seal old rings. (see youtube "project farm" he actually tested the product and it worked amazingly well in the long term on a diesel engine in a Ford tractor). Use that at your own risk, but if you don't have good compression there isn't much point in continuing with reviving the tractor for use.
3. I've found that you can get a carburetor off ebay for 60 dollars, delivered. No kidding. And they work extremely well. Yeah, it's not the original. Overhaul the original and keep it of course, but for a working tractor the knock-off carbs for sixty bucks will get you going quick, and cheap. They're aluminum, so they don't rust.
4. Switch the tractor over to a 12 volt system if you want to work the tractor. I did try to go original with a 6v system on my 52 8n (my 48 had been converted when I got it)... but I couldn't get it to start well. I did put the good, heavy cables on it and still couldn't get reliable starting. The battery was new too, from Tractor Supply. I think it's much easier to get good spark with a 12v system. You can get the 12 volt conversion kit on Amazon, eBay, or other places. (note: if all else is in good order, the 6v system probably will work fine, but it's easier to maintain the 12v system, I believe)...
5. Realize that just because you're getting spark, that doesn't mean the spark is hot enough to start the tractor. This fact came to me pretty late, after I had racked my brain over and over... the info is here in the archives, multiple times... but I hadn't seen it. If you're getting fuel, and getting spark, but not getting the tractor to start--it could be that a jump start from another 12 volt vehicle will make the tractor start. If the starter is taking so much of the battery's power that there isn't enough left to run the coil for a good spark, the engine won't start. The spark may well be there... but if available power is being mostly gobbled up by the starter, the spark voltage may not be hot enough to ignite the gas.
6. Always shut the tractor off by shutting the fuel off at the sediment bowl. Let it run until it quits, then turn off the key. This will keep the carburetor clean. The needle valve and seat on the Marvel Schleber carb doesn't always stop the flow...
7. To start the tractor, it might be best to turn the fuel on for about 10 seconds, then turn it off. Don't use the choke too much, as this will cause the engine to flood... spark plugs get wet with gas and even ether (starting fluid) won't get it to hit (that's been my experience). If you don't get the engine to start after about 5 seconds of cranking, "blip" the choke for a second at most, and see if that helps. If you pull the choke and crank on the engine over-and-over... it'll almost certainly flood. This is bad for your plugs, and even worse for your engine oil as the raw gas will run into the crank case.
8. Get a test light, 12volt if you're on a 12 volt system. Ground one end (battery - terminal or frame, test to be sure you have a light by touching the probe to the + battery terminal, and you're ready to test)... You should have power across both terminals of the amp meter on the dash board, and on one terminal of the key switch in the "off" position. When the key is on, you should have 12v on both sides of the terminal. The switched side of the key switch goes to the coil. Be sure you have voltage on the coil with the key on. Don't leave the key on long, because if the points in the distributor are touching or near touching, arcing could ruin the points. If you have voltage going to the coil, but still no spark, your problem is either the coil itself, or coil/plug wires... or the points in the distributor. There are tutorials here and elsewhere that will help with this. With the front distributor tractors which are used up until 1950 (I believe) the coil can fail most easily, so keep an extra on hand. Be sure you order the 12volt version if you've converted to 12v, that is.
9. There is a resistor on the inside of the dashboard that has about a 1 ohm value. You should be reading voltage on *both* sides of this resistor when the key is on. If you have voltage (test light comes on) on one side of that resistor block, but not the other, the resistor is bad. For my 1952 tractor which has the standard automotive 12 volt ignition coil, I did not use a resistor. Fir the front mounted distributor models, I am told it is best to use that resistor. They are not expensive.
10. There is no overflow tank for the cooling system. You need to leave about 3 inches of room at the top of the radiator so hot water/anti-freeze can have somewhere to expand to. You're supposed to fill the radiator only until the cooling coils are covered in the tank. If you have over-filled your radiator, you will get "boil over" and you'll think something is wrong, when there may be nothing wrong. But be sure you keep the fan belt at proper tension, or it will not spin the fan well enough to cool the radiator.
I'm sure there are other things, but if I had seen a list like this 2 years ago maybe I'd have had a lot less trouble. I'm still learning. I'm sure there are list out there which have been compiled by wiser folks than me, but there is my list. Hope this can help someone somewhere down the road.