Kubota B7100 Overhauled now will not run

   / Kubota B7100 Overhauled now will not run #71  
The transmission on this tractor isn't very smooth. If you are moving forward and let off the pedal mine will slow down, but you have to press reverse to completely stop.
 
   / Kubota B7100 Overhauled now will not run #72  
The transmission on this tractor isn't very smooth. If you are moving forward and let off the pedal mine will slow down, but you have to press reverse to completely stop.

The roller on the centering V plate may need some attention.
 
   / Kubota B7100 Overhauled now will not run #74  
G'day you say they have checked piston to bore clearance but have you checked ring end gap?

Jon
 
   / Kubota B7100 Overhauled now will not run
  • Thread Starter
#75  
JUne 26 UPDATE

I fully disassembled the entire motor and too back to machine shop. All parts within tolerances. All piston end gaps good. The cam plugs are tightly in place. Before putting it back together I staring blowing out all passages in the block and noticed no air at port for oil pressure sensor. As some may recall from earlier, I had an oil leak at the back of the engine the first time I tried to start. There was a missing plug in an oil galley port at the back of the block after receiving from machine shop. So I found this "missing" oil plug screwed into the hole for the oil sensor. It was in far enough I could thread in the oil sensor so far I did not realize what was happening. THUS, I HAVE OIL PRESSURE - THAT IS NOT A PROBLEM.

When reassembling this time, I believe that I had the crankshaft timing one cog off before. I found the dot to align with the idler gear under a thin flat washer. Last time, I could not see it and just tried to bring the front (#1) piston to TDC, but now believe I was off one cog. Anyway, I got it all back together this weekend, built a makeshift engine stand so I could isolate it from the transmission and hydraulic lines. It started right up and idled just perfect for about 4 to 5 minutes and then died as before. Actually, before it would only run about one minute before getting hot an apparently ceasing. I did not attempt to restart, but checked the temp of the head/radiator. The head was hot, could not touch without discomfort. The top radiator hose got hotter after sitting for a few minutes but I could not feel any heat much below just the very top. I seems as though the heat was conducting through still water and not as though there is any flow of water through the system.

I did get a new head from Kumar Bros., as the old head was cracked. I thought I checked it closely to make sure it matched the original head, as I seem to recall when ordering that they did not have one that matched the parts number in my booked but they assured me it was correct. I think that the issue is in the head and a lack of any water movement allowing it to cool. I am considering pulling off the radiator and trying to flush water through the head/block with a garden hose. Anybody have any other suggestions? I may have to take the head off again just to satisfy myself that there are not mismatched / blocked ports at the block-to-head contact.

I am also curious about installion of the flywheel. The repair manual says to just install and if runout is off, then reposition flywheel. When I put it back together this time, I rotated crank until I had number one cylinder on the compression stroke based on valve position and when went a little further to approximate TDC, as I already had the head installed. I then aligned the timing marks on the flywheel to where TDC was closest to the side where it would be seen in the alignment hole of the transmission housing. Will the flywheel bolt on only when properly aligned with the crank or can it go on being misaligned? There is nothing on the end of the crankshaft, like a key, to ensure proper alignment that I can see.

I guess I am starting to recall why I have not done this in 20+ years!!
 
   / Kubota B7100 Overhauled now will not run #76  
The flywheel will only bolt to the crankshaft in one position. The holes will only line up in one position. The holes may look close but the bolts will not be close enough to hand thread in.
 
   / Kubota B7100 Overhauled now will not run
  • Thread Starter
#77  
The flywheel will only bolt to the crankshaft in one position. The holes will only line up in one position. The holes may look close but the bolts will not be close enough to hand thread in.

Thanks D2Cat. I was curious about that as it seemed to only want to go on in that one position, but I tried to make sure the position made sense based on the crank position just in case. I am relieved to know at least that part has to be correctly installed.
 
   / Kubota B7100 Overhauled now will not run
  • Thread Starter
#79  
Post twenty.

Yes, back to Post #20. All holes in head, block and gasket seem to be correct, so I do not think there is obstruction at that point. I will try the garden hose this weekend and see what that shows. I cannot remember for sure now, but it seems as though the opening at the front of the head where the flange that holds "altenator" bolts on was smaller on the new head. I hope not to take the flange off again as that was a pain to get it to seal up without water trying to leak through the bolt hole that holds the "altenator."
 
   / Kubota B7100 Overhauled now will not run #80  
With no water pump or thermostat you should be able to flush water both ways thru the engine and radiator.
Hopefully a Flush either way may indicate a problem area. Just curious, have any frost plugs been changed?
 

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