MF188 relief valve issues

Ausmac · Mar 9, 2021

Hi all, I recently lifted a heavy load, or medium load on a job way out from the arms and while moving the trailer under the load the pump or relief valve started squealing and the load dropped a bit.
Have I ruined the relief valve?
Now it seems to be noisy with even a light load on the lift arms.
Is the relief valve easy to replace or is it a lid off job?
Thanks Mac

Ausmac · Mar 10, 2021

Hi all. So I am going to attempt to test the pressure of the hydraulic system before I race out and buy a new relief valve.
Is the plug on top of the housing with the flats on it the correct place to test?
Also, what thread is it? A 3/8 bsp fitting won’t go in but looks to be the same thread.
Also how do I get maximum pressure? From the looks of things I should be around 2950psi, does this sound right?
Sort of excited to get to the bottom of this, haven’t done work on the hydraulic system before.

K5lwq · Mar 10, 2021

I would test using one of your loader connections. Rig up the fittings for your gauge so you can put in line with your curl function. Then you can use the valve to take readings without damaging your system.

You could have a piece of trash holding the relief open. Just a thought.