Ford 640 hydrolics are weak

Just bought a Ford 640 and a 5 foot shredder. The hydraulic fluid was milky and it wouldn?t lift the shredder, so I drained it and replaced it with the proper amount of UHF. The tractor will now lift the shredder about 12 inches but that?s it. I think the hydrolics need to be flushed better or something. Does anyone have any ideas or suggestions?

Did you bleed the air out of the pump.?Is it hiccuping when lifted. It sounds like your cam pin is worn out or your unload valve is sticking. Type in search bar 640 hydraulics and see what pops up.

(quoted from post at 14:08:00 02/19/18) Did you bleed the air out of the pump.?Is it hiccuping when lifted. It sounds like your cam pin is worn out or your unload valve is sticking. Type in search bar 640 hydraulics and see what pops up.

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I being no expert in the matter would pull the lift cover off to inspect the cam follower pin as suggested by riverodrat. Sounds like the same problem I had with my 640. Also while you/re in there you can really clean out the muck at the bottom. Feel free to ask more questions as needed

The tractor will now lift the shredder about 12 inches but that?s it.

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Does it affect lift height if you change the mode selector valve from Position to Draft Control?

It may be more than one problem as already mentioned. It's best to do as much troubleshooting as possible before removing the top cover.

As Hobo suggests; to determine if it's a sticky unloader valve or an adjustment problem, you can manipulate the control valve through the hydraulic oil fill port. Push the control valve in all the way (toward front of tractor). If lift comes to the top, you have an adjustment or wear issue with the internal lift linkage. If anything less than full up, it's an unloader valve or back pressure valve problem.

Whut DB said...

Rebuilt a lift cover yesterday waiting on a lift cover gasket.

Symptoms.

1)Would only lift 10" are so.

Screwdriver thru the fill plug it lifted all the way up What I am sure of Cam follower pin worn thru about 3/4 of the way...

2) has cold shivers Its not that cold outside... but shivers like I do when I an cold. It will shiver manually are with the position control leaver...

I found the unloader to not be stuck it was to loose the o-ring looked good but not providing any seal at all the unloader valve would fall through the bore in the housing obviously to loose... Install a new -114 o-ring it stays put now this is were it gets interesting the unloader has to float it needs to be just tight enoufh it moves EZ and will not fall out of the bore but close. I am gonna guess I have the feel for them it takes just a few pounds of pressure to move it thru its complete range with no sticking....

Lift cylinder o-ring...

I did not see any leaks out the end of the lift cylinder I found the lift cylinder o-ring to be intact but the backer washer (leather) to be dissolving most of it was MIA it was decaying away...

At the point I was I knew it would lift I knew I was going into the lift cover so I took care of that first... I hope this takes care of my issues if not then I will focus on hydraulic pressures.... I will ask those questions if I get to that point. I have ruled out what I know :wink: the shiver is still in question... I am gonna wager he will live with the shivers as long as the lift works at his full range... I am gonna hope the shivers were something to do with the unloader and lift piston o-ring...

Pix if you go there...

DB, I've never seen a brake lock turned in that direction. Does it work better in that position?

That photo is Hobo's but I'm thinking someone put it on backwards.

(quoted from post at 20:48:23 02/20/18) DB, I've never seen a brake lock turned in that direction. Does it work better in that position?

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Don't know never tried that brake lock... The ones on the tractor I am working on went in the back bolts they don't work froze up... He wants it fixed his wife wants a estimate I never gave her one on the lift repair and don't plan to give her one on the brake lock... His wife will just have to get over it...