Kubota B7100 Overhauled now will not run

[Hooked_on_HP]

Did you check the ring end gap before you installed the pistons. I am thinking you don't have enough end gap and the engine is trying to sieze. After the engine dies try turning it over by hand and see how hard it turns while hot. If its is tight I would tear it back apart to see what is wrong before you tear it up
Bill

 

[TomNOh]

Has oil pressure been checked? Connecting rod caps mismatched? The rod caps MUST be put back on the rod that they came off of & MUST be put back on in the correct orientation. i.e. cannot be flipped the wrong way.

 

[Sanddog]

Is the lower radiator getting hot also. Your description gives thoughts on circulation restriction. Running a water hose in either direction on the bottom hose should indicate if all is clear. Any head gaskets that could stop/interfere with circulation? Remember it is thermo syphon and there is no water pump.

The radiator is hot at top if I only run one time and you can feel the heat slowly spread after running the motor the short run it makes before dieing. If I run several short runs, then the entire radiator gets hot, so I think the water is moving.

 

[Sanddog]

Did you check the ring end gap before you installed the pistons. I am thinking you don't have enough end gap and the engine is trying to sieze. After the engine dies try turning it over by hand and see how hard it turns while hot. If its is tight I would tear it back apart to see what is wrong before you tear it up
Bill

I do not recall checking the end gap? We bored the block and went back with the oversized pistons. I bought the oversized overhaul kit that included piston, rings, all bearings etc. Should those rings not have been sized correctly without having to be filed down???

 

[Sanddog]

Has oil pressure been checked? Connecting rod caps mismatched? The rod caps MUST be put back on the rod that they came off of & MUST be put back on in the correct orientation. i.e. cannot be flipped the wrong way.

I do not have an oil pressure gauge, but the oil pressure light comes on when ignition is turned on and the goes out after it starts. I did install a new oil pump and I know it is pumping oil, as I had an oil leak when I first tried to start it (shop left plug out of oil galley at back of block and has now be replaced). The rod caps were not mismatched and end caps put back in same orientation (was very careful about that). Now wondering about ring end gaps though!#!#!

 

[murphy1244]

Ring end gaps should at least be checked. We would put them in a cylinder or 2 end use a feeler gage to check.

 

[truckdiagnostics]

I wonder if you have head issues, getting hot and compression is getting into the water passages causing the poor water circulation and lack of power. When it is running you seeing bubbles in the radiator? Or with radiator pressure tester installed is the pressure rising?

 

[Hooked_on_HP]

I do not recall checking the end gap? We bored the block and went back with the oversized pistons. I bought the oversized overhaul kit that included piston, rings, all bearings etc. Should those rings not have been sized correctly without having to be filed down???

I always check all clearances. Mistakes happen. I have seen the wrong size rings in kits. Even 1 wrong piston out of 6.
Bill

 

[Hooked_on_HP]

Do you have a hydraulic pump on the tractor that could be building too much pressure and bogging the motor.
Bill

 

[Sanddog]

Do you have a hydraulic pump on the tractor that could be building too much pressure and bogging the motor.
Bill

There is the factory hydraulic pump that runs off the end of the short "cam" shaft that actuates the injection pump. I had wondered if somehow it was building up enough pressure to bog things down.

I did the overhaul back over the Christmas holiday and it has been long enough now that I just cannot remember for sure checking the ring gap. As I said earlier, I know I did not file anything down or I would have remembered that. So, I am going to (next weekend??) pull the motor back off and pull the pistons to make sure the ring gap is not an issue. The motor seems to me to be trying to cease up and I had better pay attention to what I am observing. It will at least give peace of mind that nothing is off internally and I am not doing damage trying to start it to check other possibilities.

Thanks for pointing this out, as I may never had though to go back and check.