International 2400a Gas Dies Under Load

I am trying to diagnose an issue with a new tractor that I bought at an auction. The problem is after working the tractor for about 30 minutes with a bush hog or box blade the tractor will lose power and begin to sputter and try and die under load. If i remove the load on the engine it will come back to life.

I started to try and fix the problem with a full tune up that included:

-carb rebuild(including screen on inlet)
-blew out all fuel lines
-pulled fuel bowl and cleaned/checked screen
-tested fuel pump flow(seemed sufficient)
-new condensor
-new coil
-new plugs and wires
-tested t-stat opening in boiling water(good)
-compression tested each cylinder cold(one cylinder was at 90psi the rest were 120 or so)

I know for a fact the exhaust manifold is cracked, I can hear it when running the tractor.

After all of this I am still seeing the same issues. My next thought was it might be overheating, my gauge does not work so it is hard to tell. The last time it sputtered I pulled the radiator cap and was surprised to see there was no pressure and coolant to the proper level. I thought at the very least there should be pressure in the radiator.

After the radiator check I decided to remove the radiator and water pump for closer inspection. The radiator has good flow through the inside and no sediment came out. The fins were definitely dirty and needed a good cleaning.

Next I tested the water pump, before fully draining the system i removed the t-stat and started the tractor without the radiator connected. I expected to see water come shooting out of one end of the water pump but it did not, a slow 1/4" stream came out. I also shoved a garden hose in each side of the water pump and flow did not increase at all.

Does the weak flow from the waterpump seem normal? Shouldn't the radiator have some kind of pressure when the tractor is up to operating temperature? Any other thoughts on what to look for to diagnose my original issue.

Your engine may be running lean. If that carburetor has a main jet adjusting screw you need to open it. Also check the vanes in your water pump as they may be worn. Touch the bottom radiator hose lightly with your hand to see if that hose is hot. Hal

You've probably got a burned valve on the cylinder with 90PSI. The engine gets hot, loses compression because the valve isn't sealing, and loses power.

Did you try running it with the gas cap loose?

I have tried pulling the cap off the gas tank when it starts acting up. Do you think it is too late at that point? I can try running the tractor w/out the cap while working it.

The tractor should recover and run fine as soon as you remove the gas cap if that's the problem.

Spark plugs with too high of a heat range will cause that problem. Try Champion D15Y or equivalent plug in the brand of your choice.

We have the same tractor with the c-175 in it. You probably have the c-157. We also have the same exact issue. In our case it"s a head gasket, and probably a burned exhaust valve from overheating. We also have a cracked manifold, but we replaced that. It warms up, loses compression, and then goes to pieces and barely runs. Not as bad in really cold weather, but in hot weather it doesn"t last long. We also threw all those parts at it that did with no avail. We must have gone to the same auction. I"d suspect the same thing with yours. Good luck.

It turns out that this was caused by a timing issue. I adjusted the timing to spec and the tractor runs very nice after 3 hours of heavy brush hogging. In the process I did give the radiator a very heavy cleaning which may have helped as well.