Near catastrophic 3 point hydraulic nightmare.. Massey

[Gulkana]

I am finally getting this little Massey Ferguson M35 diesel tractor up and running. The 3 point system on it wasn't working properly when I got it. The previous owner told me it would only go up about 6 inches and slowly at that. He had a guy put in a new cylinder and piston a few years back but said it still wasn't working correctly and the tractor sat not running since.
I installed a gauge on the cover to check the pump pressure. I engaged the lift lever and the pressure shot all the way around the dial and pinned back at zero. Then one of the studs on the cylinder flew out of the top of the cover and across my shop. I shut everything down and pulled it all apart. Below are a few photos. I have no idea what happened to the piston. The cylinder was pushed away from the bottom of the cover and 2 of the 4 studs were broken off. It looks as though there was no releases of fluid and it just built up until it pushed the cylinder. I suspect the safety relief valve is shot. But I dont know what exactly is going on here. The original cylinder is in the photo below the one with the huge crack in it. The PO installed a new cyclinder at some point. I sent a magnate through the case and I only found the debris from the cylinder damage. It doesnt look like anything else is broke. I did check the pump pressure via the tube at the top and fluid is coming out when engaged so it looks like the pump is working. I am thinking the safety relief valve failed but I don't have a lot of expiernece with those and what happens when they fail. Anyone have any idea what went wrong?

 

[Cougsfan]

I'm guessing your relief valve didn't relieve alright, but there is likely something else wrong too. I would have never imagined you could develop so much pressure to blow a stud out. The stud isn't stripped, so I am wondering if someone didn't even screw it in?

 

[KWentling]

You would think a pressure relief valve would open before that destruction would happen. I'm not at all familiar with your tractor, but I would think there would be some device to cancel the raise input before the cylinder deadheaded. If there isn't it would be a first in my limited experience.

 

[SPYDERLK]

The piston rod to fit into the socket in the piston is not displayed. Is it missing?

 

[Gulkana]

Do you mean the rod with the two round ends? One that has the hole through it that the pin goes through to hold it in place? If you mean this rod then I didnt have it in the photos. I mocked up the cylinder to see the levers for a reference. I left out the rod for that purpose.

 

[SPYDERLK]

Yes. I was concerned at its absence considering the mystery of the failure.

 

[Agvg]

Get a manual, replace parts and start adjusting everything from the pump and up by the book, it's not a system that works well if you just wrench without knowledge.

 

[shaeff]

I agree that the pressure relief valve either failed to open, or that even if it did open (you'd hear it squealing), that the position or draft levers were in constant pumping position and it topped out, overstressed the cylinder and the studs, and blew it apart.

I used factory parts to rebuild the pump instead of buying a new pump, simply because I wanted to understand how it all worked. If you search my name, probably my first post is a lengthy thread about the repair process. Take note- my thread isn't meant to teach anyone, it's just documenting what I did and the mistakes I made along the way. A fellow member PM'd me a few years back to ridicule me about it, apparently thinking I was trying to teach. I was/am not. Just showing what I did. Cliff notes: I reassembled the pump with the cylinders upside-down. Live and learn. If you follow my thread, read the ENTIRE thread before attempting to repair your pump if you decide to do so while you're in there. I don't want you making the same mistakes I did.

I also upgraded to thicker studs and the late model cylinder to accept those studs. I had to drill out the top cover to accommodate. Easy enough process.

Cliff notes: either your stop isn't set on the constant pumping (dangerous, you can crack the top lift cover) or the relief valve failed. I'm just going to guess that this was an adjustment error, likely from the previous owner. Good luck repairing it, adjusting the linkage is finicky and I hated that part. The rest wasn't bad at all.

Edit: here's the thread- pay no attention that it's a 35 Utility, in this respect it's basically identical to your 35.

Repairing MF35 Utility Hydraulics

Some of you may remember my thread from a few months back: http://www.tractorbynet.com/forums/massey-ferguson-classic-vintage/347197-early-60s-mf-35-utility.html Well, life got in the way for a while and the tractor was on the back burner for a few months while I sorted out other issues. To sum...

www.tractorbynet.com

 

[Gulkana]

Update on the hydraulics! working like a champ now! I ended up replacing the cylinder pump, piston, rings, safety relief valve, filter, studs and fluid. I put a gauge on it and it topped out at 2800psi. I reset the adjusting nut and bolt to 1/2 below full rise in order to shut of constant pumping. Working great now! Thanks to everyone for the help and insight. Ironic right when I get it all operating correctly the rain comes and the forecast is 14 days straight rain. It looks like I won't get an implement on it for a while.