1969 MF40 hydraulics question...

torker · Nov 5, 2008

Hey guys! I'm new here and really huntin some advise.
My ol' MF40 is driving me nuts.
The frontend loader has a very expensive issue. I had to bump up the pressure when I got this thing home to get the backhoe and the loader to work.
I just kept upping the pressure in the main relief valve til everything started to move.
Now...for some reason the curl cylinders on the FEL bucket are deadheading the pump. I blew a hose last week after it gave a grunt.
Two days ago I blew the side right out of a nearly new pump.
Everything else works perfectly. The only problem is the curl. When you bring the cylinders to full travel...they just SLAM shut the last 1/2" and the pump deadheads.
Anyone have any ideas?
Thanks!
Russ in BC, Canada.

aczlan · Nov 5, 2008

torker said:
Hey guys! I'm new here and really huntin some advise.
My ol' MF40 is driving me nuts.
The frontend loader has a very expensive issue. I had to bump up the pressure when I got this thing home to get the backhoe and the loader to work.
I just kept upping the pressure in the main relief valve til everything started to move.
Now...for some reason the curl cylinders on the FEL bucket are deadheading the pump. I blew a hose last week after it gave a grunt.
Two days ago I blew the side right out of a nearly new pump.
Everything else works perfectly. The only problem is the curl. When you bring the cylinders to full travel...they just SLAM shut the last 1/2" and the pump deadheads.

I would disconnect the curl cylinders, take them off and see if they move freely, probbaly one is messed up in some way (bent)

Aaron Z

kennyd · Nov 5, 2008

You never put a gauge on it when setting the relief valve?

torker · Nov 6, 2008

Aaron.. I'm thinking the cylinders are ok. I've been using the hoe for a couple weeks now and if the rods or whatever where bent you'd be able to see it...no? This only happens when the rods are fully drawn in. I can draw in all the other cylinders and hold them in for as long as I want and the relief works fine. I'm more thinking it's something is missing or otherwise from the relief that controls the curl cylinders. The last guy who owned this machine did some weird things to it. He "mentioned" that you couldn't get parts for the loader valve so I'm sure he knows something that he didn't want to share.
This has a very old (OEM ?) Parker Hannifin twin stick control.
Kenny...(blush)...nope I never put a guage on it. I better buy one today.
LOL! I'm scared to even start the thing up now as I don't want to blow another pump.
I'm trying to avoid getting a hydraulic tekkie here. I've worked with these guys in the past (I'm a weldor) and I know how they operate.. $125 an hour and once they are parked on your property they like to make a day out of it.

Wayne County Hose · Nov 6, 2008

Hello Torker,

Fill out your info and stop painting with a broad brush. Not all of us guys here are out to rip people off. I probably give away as much as I sell.

First thing you need to do is back off on that relief valve. Get yourself a good gauge and slowly bring that relief valve up to spec. Then see how everything works. Probably at some point before I did too much, especially with a grenanded pump, I would also change the fluid and filters. Get this stuff done then be real specific with what works and what doesn't.

BTW, you make great intake manifolds.

Good luck, Andy

torker · Nov 6, 2008

Andy...Geez...I was in such a hurry when I registered I never got time to fill in my profile. It's done now(I hope)
I talked to an old guy who fixed thisa stuff for years and he thinks he knows what it is. These controls have problems peculiar to them alone. This one he thinks has some little "top hat" poppet that's worn out and he thinks I had to boost the pressure to over 3500psi to overcome the poppet and that's where the problems lay.
We'll see Monday. I'm hiring him to fix it for me.
BTW.. I'm certainly not trying to paint anyone here. I just know these particular outfits. I've owned machinery before and they've dinged me for a lot of money. They make me nervous.
Andy.. I've been on BBS's for years. You are the first one who ever figured out what my "handle" is all about. Comes from the days I used to wheel and deal in used race parts. I bought 6 Torker manifolds and it took me forever to get rid of them. I got the nickname cuz I'd keep showing up at swap meets with the same ol bunch of manifols...lol!
Russ