Kubota oil psi problems

   / Kubota oil psi problems #1  

steve01

New member
Joined
Jun 26, 2009
Messages
9
Location
Lake, Mi.
Tractor
Kubota B7100d
I've searched this on this site and have seen the problems with the plugs in the ends of the cam on the older Kubota B7100d. Mine is a 83 and has lost oil psi. It has 1300 hours on it. When you let it set and start it, if you let it idle the oil light will not come on, if you raise rpm off idle the light comes on and stays on. So here is what I have done so far.
1. Changed oil and filter
2. Cut top off old filter and looked inside, no metal
3. Removed front cover to have a look and see if plug was in front of cam, it is.
4. Removed oil pan and had a look in there no metal and is clean. Had a look at the oil pick up screen and nothing blocking it. Gave the rods and mains a shake and nothing seamed loose.
5. Put front cover back on and hooked up a old fuel oil pump to the stub that the oil filter goes on and primed it with oil and turned it on. Oil dripped from the mains and rods. Oil was running back trough the hole in the block from the front cover area. Looked inside the cover from the throttle hole and could see oil squirting from the gear in the center. Was showing about 3 psi on the gauge i have hooked where the sending unit for the oil light goes.
6. Pulled front cover again and had a look inside and looked at the gear that was shooting oil and the hole is a factory made hole. Also noted that there was a lot of oil on the front of the cam so looked closer at the cam and the plug has 2 holes in it.
So here is where i stand, I don't think the holes are supposed to be there.
Also if the front plug is bad should i change the rear also. If so what is the best way to do it remove the motor and go trough the back or pull the head and and valve train and remove the cam that way?
Here is a picture of the cam so you can see what I'm dealing with. Also I've changed the oil bypass valve, no change.
 

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   / Kubota oil psi problems #2  
Steve;

Your symptoms seem backwards to me. Usually oil pressure is lower at idle and increases with RPMs. You say that the idiot light is off at idle and comes on at higher RPMs. I think I would suspect the oil pressure sender. I would check to see if the cam plug comes with two holes from the factory and change it if yours is bad. Then I would button the motor up and hook up a known good oil pressure gauge and see what the pressures are in psi. I'm hoping it's a bad sender. Good Luck

SimS
 
   / Kubota oil psi problems #3  
You first need to remove the oil sensor sender and replace with an inexpensive mechanical gage with numerical readout to see if it is indeed a pump, gear, or whatever problem. Maybe just a bad sender. :D
 
   / Kubota oil psi problems
  • Thread Starter
#4  
I have a guage in where the sender goes. What is the best way to check the oil pump?
 
   / Kubota oil psi problems #5  
what is the pressure at idle and off idle on your mechanical guage?
 
   / Kubota oil psi problems #6  
I think he said 3 psi on the guage.
 
   / Kubota oil psi problems
  • Thread Starter
#7  
Oil psi at idle now is 0 i do have flow but no psi. Going to go to hardware store and get some fittings and make up a bypass where the oil filter goes on and put a Gage in that junction, start the tractor, let it idle, close the valve and see how much psi i have from the pump. This will also tell me that the bypass on the tractor is working. If the pump isn't pumping enough volume I'll get a new one. If it is I guess it's time to tear this thing down and see what is what.
I have a hard time believing that with 1300 hours i need bearings.
 
   / Kubota oil psi problems #8  
It sounds like you have covered all the bases. I would take a hard look at the oil pump. Check the pump and see if the main pump gear is slipping or spinning on the drive shaft. You may have to remove the pump from the engine to check it.
 
   / Kubota oil psi problems #9  
I know nothing about Kubotas but do remember some IH oil pumps have a ball and spring in the pump. If the ball got stuck open the oil pressure would drop. Hope you find something simple. That's sure not a lot of hours on the tractor for high wear.
 
   / Kubota oil psi problems #10  
Did you check the oil pump pressure relese valve. If it is stuck open you'll have flow but no pressure.
 
 
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