MS 361 oil pump problem

[Bill_G]

All of a sudden my older ms361 keeps eating oil pumps . I've put new lines in and cleaned tank . The pumps last about 5 tanks of gas then seize up . Never ran into anything like this before . Was wondering if anyone has any experience with this ?

 

[HarleyT]

What kind of oil do you use?

 

[Bill_G]

Either sthil or husky

 

[HarleyT]

What seizes?

 

[Bill_G]

The pump keeps seizing , going to check the crank bearings next .

 

[HarleyT]

Huh?
So #4 in the diagram is seized, when you take the pump off of the saw?
#11 is damaged?

 

[Bill_G]

Yes the pump seizes and strips the fiber gear