Siezed hydraulic cylinder

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Scott McCracken

New User

• Jun 4, 2010

• #1

I have a Ford 7500 backhoe. Old, but just over 1000 hours. WHile digging a drainage dithc yesterday, the hydraulic cylinder for the bucket starting moving very slowly. It acts as if it's "under a load". The engine bogs down and it hardly moves at all. When RPMS are high enough, it also starts a slow drip of hydraulic fluid under the floorboard. Any thoughts on why it would it would sieze up like this???

 

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rrlund

Well-known Member

• Jun 4, 2010

• #1

Just guessing. You must have a problem in a valve not letting the return oil out of the cylinder. I wouldn't think the problem is in the cylinder itself.

 

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rrlund

Well-known Member

• Jun 4, 2010

• #1

Just guessing. You must have a problem in a valve not letting the return oil out of the cylinder. I wouldn't think the problem is in the cylinder itself.

 

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old

Well-known Member

Location

Camdenton Missouri

• Jun 4, 2010

• #1

Hydraulic cylinders don't just lock up but the control valves that make them work do stop doing there job and that will cause funny problems. If you can do it you might switch so lines from one valve to another and see if the problem stays with the cylinder or the valve body

 

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Scott McCracken

New User

• Jun 4, 2010

• #1

Thank you, RRLUND. It appears there are some "after market" additions to the hydraulics. The hoses come out of the frame of the "dipper" arm, and go into these 2 "junction boxes". Would it be sensible to bypass these and hook directly to the cylinder and see if that works? I'm just hoping like heck to stay out of the "under floorboard" mess! I'm attaching photos.

http://i700.photobucket.com/albums/ww5/sjmdutch/DSC00001.jpg

http://i700.photobucket.com/albums/ww5/sjmdutch/DSC00003.jpg

http://i700.photobucket.com/albums/ww5/sjmdutch/DSC00002.jpg

http://i700.photobucket.com/albums/ww5/sjmdutch/DSC00004.jpg

 

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daman

Member

• Jun 4, 2010

• #1

Is that the only issue your having? 755 hoe?

 

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supergrumpy

Member

• Jun 4, 2010

• #1

prior owner may have used thumb and those boxes maybe gave "power beyond" sorta capability

simple is good

 

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Scott McCracken

New User

• Jun 4, 2010

• #1

Yes....it's a 7500. It was owned by a man that serviced it daily while he used it. He passed away last December, and they auctioned off all of his equipment. He was a good friend, so we managed to purchase it prior to the auction. It had 1100 hours on it in December. The seat was the only other problem...but a couple shots of WD40 fixed it right up!

 

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daman

Member

• Jun 4, 2010

• #1

No i meant the series model of just the backhoe,I'm sure it's a 755 if it's on a 7500,i'll check my books when i get home see if there's something you could check.

if it's only in that circuit could be a easy fix.

 

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Scott McCracken

New User

• Jun 4, 2010

• #1

Oh...sorry Daman. It's my first backhoe! I have no idea if it's a 755. It's whatever came on it originally. Here are some more pics if that helps.

http://s700.photobucket.com/albums/ww5/sjmdutch/Backhoe/?action=view&current=3.jpg

http://s700.photobucket.com/albums/ww5/sjmdutch/Backhoe/?action=view&current=4.jpg

http://s700.photobucket.com/albums/ww5/sjmdutch/Backhoe/?action=view&current=5.jpg

http://s700.photobucket.com/albums/ww5/sjmdutch/Backhoe/?action=view&current=1.jpg

http://s700.photobucket.com/albums/ww5/sjmdutch/Backhoe/?action=view&current=2.jpg

 

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MN Scott

Well-known Member

• Jun 4, 2010

• #1

Those valves are two way selector valves. They are push pull. Grab the knob and pull it one way and it directs oil to one circuit push it in and it directs oil to the other circuit. I see one of the valves is missing its knob. When you were digging one might have gotten bumped and is in the middle of the two circuits causing slow cylinder action. Make sure the valves are all the way in one direction and I bet your problem disappears. Your going to have to experiment to find out witch position the valves need to be. You can also remove them if you want as they serve no purpose other than connecting another cylinder in the circuit.

 

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gene bender

Well-known Member

• Jun 4, 2010

• #1

Are you sure the rings on the piston are OK

 

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MN Scott

Well-known Member

• Jun 4, 2010

• #1

Pictures.

<a href="http://s700.photobucket.com/albums/ww5/sjmdutch/?action=view&current=DSC00004.jpg" target="_blank">

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<a href="http://s700.photobucket.com/albums/ww5/sjmdutch/?action=view&current=DSC00003.jpg" target="_blank">

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<a href="http://s700.photobucket.com/albums/ww5/sjmdutch/?action=view&current=DSC00002.jpg" target="_blank">

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<a href="http://s700.photobucket.com/albums/ww5/sjmdutch/?action=view&current=DSC00001.jpg" target="_blank">

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<a href="http://s700.photobucket.com/albums/ww5/sjmdutch/Backhoe/?action=view&current=3.jpg" target="_blank">

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<a href="http://s700.photobucket.com/albums/ww5/sjmdutch/Backhoe/?action=view&current=4.jpg" target="_blank">

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<a href="http://s700.photobucket.com/albums/ww5/sjmdutch/Backhoe/?action=view&current=5.jpg" target="_blank">

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<a href="http://s700.photobucket.com/albums/ww5/sjmdutch/Backhoe/?action=view&current=1.jpg" target="_blank">

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<a href="http://s700.photobucket.com/albums/ww5/sjmdutch/Backhoe/?action=view&current=2.jpg" target="_blank">

</a>

 

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Scott McCracken

New User

• Jun 4, 2010

• #1

Dude! You're a lifesaver! I twisted, cranked and beat on those damned things last night with no success. Just went out and pushed both up, and SHA-ZAM! Thanks a million! I knew having an old piece of equipment meant becoming a mechanic as well...but I never dreamt of an "EASY" fix on anything!

 

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daman

Member

• Jun 4, 2010

• #1

Ok what the heck is that set up for??? never seen such a thing on a ford.

 

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Jon Hagen

Well-known Member

• Jun 4, 2010

• #1

Looking at the pictures of the splitter valves that have been added, The one without the knob is in the in position(spool snap ring touching body)

The one with the knob is in the out position, ( the spool snap ring is a good distance away from the body).
As another posted, I bet one valve has accidently been moved. try it with both in the in position, or both in the out position.

I bet one valve is in the wrong position and blocking oil flow.

 

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Jon Hagen

Well-known Member

• Jun 4, 2010

• #1

I took another look at how those add on splitter valves are plumbed, and it looks like both should be in the in position.
The one with the knob is in the out position. Push it in and I bet your hydraulic gremlin will be gone.

 

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MN Scott

Well-known Member

• Jun 4, 2010

• #1

Someone added them, they are not factory. Maybe someone had a thumb, maybe an auger, hydraulic breaker? Who knows. They would not work the best tho, to work what ever the extra outlets ran the selectors would have to be in the auxiliary position and you could not move the bucket without jumping off and switching the valves every time you wanted to reposition the bucket.

 

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Anonymous-0

Well-known Member

• Jun 4, 2010

• #1

Aux. could have been for a hoe pack as well. It's a hyd. driven compactor for trenches and backfilling holes. Dave