Finally fixed the dreaded MM55SR excavator for good.

I finally got my MM55SR sorted once and for all! I pulled a complete hydraulic system out of another digger and fitted it into mine — main pump, valve block, all the pipework, hoses and controls, the lot. Then I had to rework everything to get it to fit properly.

When the whole thing showed up from the dismantler in one massive crate, I'll admit it looked pretty overwhelming and I wondered what I'd gotten myself into. But I stuck with it and managed to get it done.

The new setup runs a load-sensing pump, so the engine performs much better now. All the controls are pilot operated too. I've even got a spare section on the valve bank in case I want to add extra lines for attachments down the road.

I reused the original cylinder hoses, and everything seated in nicely. The machine runs so much better than before — smoother, quicker, and way more responsive.

That's genuinely impressive work.

You've got to know that machine inside and out after taking it all apart like that. It really is quite the puzzle to get it all working together.

Which excavator did you pull the hydraulic system from?

Wow, what do you do for a living? That's the kind of project that needs serious organization skills plus real mechanical ability.

Yeah, I knew it was possible—just had to bite the bullet and get on with it!

Yeah, I had some basic knowledge about hydraulics before starting, but I've learned a lot more through doing this. It's way more than just the valve bank and controls—there are all these specialist hydraulic components involved that I didn't expect.

All the parts came from a 2014 Hitachi ZX50.

I work as a heavy fabricator but these days I mostly do 3D design for material handling equipment. I like to tinker with stuff too.

That's quite the undertaking to do on your own.

That sounds more like equipment for packing apples than heavy machinery.

Does anyone know what the right hand floor pedal does on the MM55SR, and how do you operate the boom slew? Thanks!