I just picked up a used (4500 hrs.) FARMALL 460 a few months ago and have been working my way through a lot of worn parts and various troubles. I thought I'd come to the end of my problems with it last week. But it still has an issue and I'm stumped.
Here's what it does. Starts up fine, choke pulled partially out until it warms up. Then it will run with the choke off. But if you gun the throttle, or put any load on the engine, it will immediately stop running. It will start right up again, but will stall as soon as you put load on it or gun the throttle. If you pull the choke partially out, you can keep it running, but it looks like it's running too rich.
Here's a list of what I've done to it.....
Replaced Ignition rotor, points, condenser, cap, wires, plugs. Subbed another coil just to rule that out. It seems to have a real good spark all the time. I've rebuilt the carburator and soaked and cleaned it, although it looked pretty good before I cleaned it. Gas tank looks good inside, and there's plenty of gas flowing to the carb. Carburetor screen is clean. I can see/hear the difference when I adjust the Idle adjustment screw and it's presently set to the sweet spot. I adjusted the ignition timing to 30 degrees Advance. The manifold heat flap and spring seem to be working very well, they're very loose and move as the manifold heats up. I removed the manifold and had it machined flat to make a good seal against the head and new manifold gasket. I checked the compression, and although not great...not terrible either. Pistons 1 & 2 are about 150, 3 & 4 are about 130, and 5 & 6 are about 150. Must be a small leak between 3 & 4, but I don't think that would cause this issue with the engine stalling under load.
I'm thinking that although is seems like two different scenarios that cause the stall out, maybe it's not. When the tractor is put under load the governor steps in and kicks up the throttle, just like when I gun the throttle by hand. This almost smells like a carburator issue to me, but the carburetor on this tractor is so simple, it's hard to believe there could be anything wrong with it. I ran wires and air through every passageway that I could find after I soaked it in Gum Out.
I'm just not sure where to look next......?
What do you all think??
Thanks.
Bob
Here's what it does. Starts up fine, choke pulled partially out until it warms up. Then it will run with the choke off. But if you gun the throttle, or put any load on the engine, it will immediately stop running. It will start right up again, but will stall as soon as you put load on it or gun the throttle. If you pull the choke partially out, you can keep it running, but it looks like it's running too rich.
Here's a list of what I've done to it.....
Replaced Ignition rotor, points, condenser, cap, wires, plugs. Subbed another coil just to rule that out. It seems to have a real good spark all the time. I've rebuilt the carburator and soaked and cleaned it, although it looked pretty good before I cleaned it. Gas tank looks good inside, and there's plenty of gas flowing to the carb. Carburetor screen is clean. I can see/hear the difference when I adjust the Idle adjustment screw and it's presently set to the sweet spot. I adjusted the ignition timing to 30 degrees Advance. The manifold heat flap and spring seem to be working very well, they're very loose and move as the manifold heats up. I removed the manifold and had it machined flat to make a good seal against the head and new manifold gasket. I checked the compression, and although not great...not terrible either. Pistons 1 & 2 are about 150, 3 & 4 are about 130, and 5 & 6 are about 150. Must be a small leak between 3 & 4, but I don't think that would cause this issue with the engine stalling under load.
I'm thinking that although is seems like two different scenarios that cause the stall out, maybe it's not. When the tractor is put under load the governor steps in and kicks up the throttle, just like when I gun the throttle by hand. This almost smells like a carburator issue to me, but the carburetor on this tractor is so simple, it's hard to believe there could be anything wrong with it. I ran wires and air through every passageway that I could find after I soaked it in Gum Out.
I'm just not sure where to look next......?
What do you all think??
Thanks.
Bob