A hydraulic pump dont build up pressure.What can it be??

Question

A hydraulic pump dont build up pressure.What can it be??

Answer 1

The return valve (safety relief back to the suction), is stuck open.

Leakage from 'O' rings and gaskets are generally too small to prevent pressure build-up.

The return valve is meant to relieve excess pressure quickly.

If it's jammed open, pressure can't build up.

Answer 2

I'm thinking you have a bad seal somewhere or you are really low of hydraulic fluid. I'd check the fluid first.

Answer 3

Leakage past bad gaskets or past O-rings / Seals

Answer 4

The valves could be bad.

Answer 5

also it could be air inside the lines.