belarus 1989 420a

Need some help with a belarus 420a tractor. I bought it used and ran it for 3 hours noted it was running hot way hot near the 120 C line. I stopped the engine let it cool for about an hour it started fine and drove back to the barn. When I parked I started to lower the bucket and it stalled. Has not started since. I have done a dozen things to start it again, checked filters lines etc but am stuck any ideas??

Hi that's a 4 cyl air cooled motor If it's the same tractor we have in Canada, Maybe it didn't like running that hot and she has seized in a cylinder or on the crank shaft. And won't turn free enough to fire, could be warped heads too and loosing compression, does it make unusual hissing type noise not heard before when cranking.
I seem to remember from years ago that gauge works on oil temp so it got pretty hot. Have done way more with water cooled Belarus than these air cooled old girls.
Have you cracked the fuel lines at the injector nuts and made sure you got fuel up there when cranking the motor. could be pump issues even, but kinda doubt it with the heat problem, It's a Belarus anything can happen and usually does in multiple event's L.O.L.
It's pretty hard as a mechanic that can't see or hear whats going on to diagnose whats happening, so can only make educated guesses with this.
Regards Robert

Hey thanks for the reply, I did crack the fuel lines at the injectors and im getting no fuel there. I also took off the booster pump and looking inside at the cam shaft for the fuel pump as I turned it over I did not see it rotate. I think it might have broke a gear that runs the pump. I have fuel to the top of the pump from a electric fuel pump but I dont think the booster is kicking in allowing it to open the port to allow fuel in the line to the cylinders. Does this make any sense. No there are no unusual noises that were not occuring prior to this, it turns over fine but no smoke and no start.

Hi
I have never seen one break the drive from the timing case to the main fuel pump. I have had the odd 250 2 cyl loose a couple of teeth internally on the pump metering gears, under the square plate on the side of the pump when the element seizes, and the motor tries to turn it. This then means the metering unit doesn't turn to pump fuel up the high pressure lines. Maybe thats happened and jammed the pump and then sheared the drive?.
It certainly is not good if you got the primer pump off and cant see the cam turn with the motor.
Regards Robert

evening: Just to add 2 cents worth...
Your high temp concern might be from loose fan belts, which run the cooling fan/alternator, or blocked intake screen? or excessive dirt and chafe in the cooling ductwork,around the cylinder fins.
In cold temps they came equipped with a blanking piece which mounts on the outside of the air intake screen/houing[ right side of the engine],surley this wasn't put on sometime and left? there are 3 or 4 cam locks that hold the actual housing on, so its easy to check for blocked cylinder fins, and also the oil cooler itself is located inside and next to the clyinders, it might be also packed with chafe and dirt?
And some of the tractors had a flow control to the cooler for extreme cold temps, is this closed off? 1979 machine here does not have it.
And of course the actual temp gauge could be at fault, can be tested in hot water, and you only have this fuel problem to deal with?
Be sure to check the primary and secondary fuel filters also, i have seen enough crud collect that the canister rusted out... and they use the fuel to lub the injector pump itself, maybe there was/is a lack of fuel from the filters and hence the possible pump damage, or gear train as suggested already?
hope it helps and send the final result back just to know what happened.
good luck

Thank-you all again for the comments and help. I have found numerous things going on since I started this project, but still believe once this old work horse is up and running all will be well.
I do still have an issue with either the fuel pump or gear/cam that drives it. Having a disel mechanic comming today to help walk me through the removal and inspection of that.
As far as the overheating...lol....do you think multipal mouse nests blocking over half of the air cooling area, 1/2 inch to 3/4 inch of guck and filth on top of filters inside the oil bath could have something to do with it.
Have been going thru entire system cleaning changing fluids and everything else maintenance related, hope the pump turns out to be relativly minor and I can get some food plots and brush hogging done.

Morning :
I see where you found the heat problem...., and i rememebred something you had wrote before" an electric fuel pump" and got to thinking.
There shouldn't be a need to use an electric pump actually, so a interest as to why?The fuel system is a gravity feed through the filters and suction comes from the main fuel pump itself, Couple thoughts here: With pressure from the electric pump against the filters they might/have collasped internally?
Are you getting a steady, but not forceful fuel flow on the main inlet to the fuel pump? If the fuel is pressurized to the pump, a possible chance of blowing a internal seal exists? If the electric pump is bypassing the filters, all the crud in the tank just went to your fuel pump, but i assume the filters are in service.
The manual priming pump will pump fuel to and through the main pump, to where you can open the air bleed off screws, once fuel is to that point, rolling the engine with open injector lines will get it going.
Quicker to open the injector lines at the pump discharge first, get fuel squirting out and then close them, then open the lines at the injector themselves.
And also check that the return fuel line is not plugged off, should be piped but over time hose might of beeen used and it is pinched somehow?
oh yeah the manual pump will feel like it doing nothing??? try rolling the engine a little bit and the operating feeling could change, don't be surprised if fuel leaks out around the actual rod as you push it in/out, it seals off when you screw it back into place.
Thats it, and still curious how you make out with it.