Rev instability

[ursus]

Hi
My Ursus C385 with a Zetor 8401 motor is very unstable and its speed shifts heavily up and down. Is it difficult to demount and refit the governor? What can go wrong?

 

[dave_peters]

First thing to do is check the oil level in the governor housing.

 

[ursus]

Thanks for reply.
I have dismantled the governor and everything looks fine. I think the problem is the injection pump. Any suggestions?

 

[Renze]

Have you tried adjusting the spring pressure of the governor ? when i tried to adjust the max. hp of our 5245 i adjusted the wrong spring: It wouldnt go over 1000 rpm anymore. when i put too much tension on it, it was very unstable and constantly adjusting the revs up and down, as you describe.

If you put more, or less, tension on this spring, it should adjust the revs better. I assume that yours has too little tension, because normally the spring would not get stronger over time, but weaker.

 

[ursus]

Thanks for the tip
I have tried to adjust the spring and it had some effect. When the motor is cold it is reasonable stable but as soon it gets warm it shifts speed up and down