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 Post subject: MEC 9000H Hydraulic Piston sticking
PostPosted: Fri Feb 12, 2021 10:12 pm 
Field Grade

Joined: Thu Jun 04, 2020 7:05 pm
Posts: 49
Hey all,

I just rebuilt the hydraulic piston on my 9000H. I ordered replacement orings and a nylon guide from McMaster. They are direct replacements to what was in there. I'm now having an issue where the machine and piston will not return to the top of its stroke. I can manually pull the head of the machine up, although it requires some force. If I run the piston detached from the machine, it will only return about half way. If I attach the piston to the machine, it will stop on return with about 1 inch left before the top of the stroke.

I've read the threads about lubricating and loosening the collet due to sticking. The collet is not sticking on the machine. It is fully disengaged when the machine stops. I've bled all of the air from the lines. I've tried removing the hydraulic line when it is stuck, thinking maybe it was being hydraulic locked. No dice on that either. I've triple checked the valve, and it is fully open. The only thing I can think of is either the 2 springs in the piston are weak due to their age, or the new o-rings are too tight, even though they are an identical match to the o-rings that were in there.




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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Fri Feb 12, 2021 10:20 pm 
Crown Grade
User avatar

Joined: Sun Jun 24, 2018 2:51 pm
Posts: 2371
Location: S.E. Wisconsin
All hydraulic pumps have a pressure relief valve. It is how you set the max pressure of the system. MEC's come set from the factory at 600 psi. Yours could be weak and you are not getting 600 psi or the new parts are just stiff because they are new. Turn it up a LITTLE and see if your problem goes away.

Steve

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The More Times You Pull The Trigger The More Fun You Are Having.
I repair MEC presses. PM me.
Used to be Steve Y


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Sat Feb 13, 2021 1:00 am 
Field Grade

Joined: Thu Jun 04, 2020 7:05 pm
Posts: 49
YevetS wrote:
All hydraulic pumps have a pressure relief valve. It is how you set the max pressure of the system. MEC's come set from the factory at 600 psi. Yours could be weak and you are not getting 600 psi or the new parts are just stiff because they are new. Turn it up a LITTLE and see if your problem goes away.

Steve


The pump only works on the downstroke, so increased pressure won't help me on the upstroke. I was able to fix it though. I flipped around an o-ring inside the piston and now it's working fine.


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Sat Feb 13, 2021 5:59 am 
Tournament Grade
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Joined: Thu Oct 10, 2019 6:52 am
Posts: 177
Any chance you could provide the parts list and an overview of the rebuild process?


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Sat Feb 13, 2021 8:49 am 
Crown Grade
User avatar

Joined: Sun Jun 24, 2018 2:51 pm
Posts: 2371
Location: S.E. Wisconsin
surgikill wrote:
YevetS wrote:
All hydraulic pumps have a pressure relief valve. It is how you set the max pressure of the system. MEC's come set from the factory at 600 psi. Yours could be weak and you are not getting 600 psi or the new parts are just stiff because they are new. Turn it up a LITTLE and see if your problem goes away.

Steve


The pump only works on the downstroke, so increased pressure won't help me on the upstroke. I was able to fix it though. I flipped around an o-ring inside the piston and now it's working fine.



DUH, and I knew that. {F* Going to blame it on covid shot brain.

I would also be interested in the part #'s you used from McMaster.

Steve

_________________
The More Times You Pull The Trigger The More Fun You Are Having.
I repair MEC presses. PM me.
Used to be Steve Y


Last edited by YevetS on Sat Feb 13, 2021 9:04 am, edited 1 time in total.

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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Sat Feb 13, 2021 9:00 am 
Tournament Grade

Joined: Thu Oct 03, 2019 8:22 pm
Posts: 115
....I don't follow how you "flipped around an O-ring" or what you did. What prompted you to do that?
I ask to learn, not doubt.
H


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Sat Feb 13, 2021 10:31 am 
Field Grade

Joined: Thu Feb 21, 2019 2:06 pm
Posts: 21
surgikill wrote:
Hey all,

I just rebuilt the hydraulic piston on my 9000H. I ordered replacement orings and a nylon guide from McMaster. They are direct replacements to what was in there. I'm now having an issue where the machine and piston will not return to the top of its stroke. I can manually pull the head of the machine up, although it requires some force. If I run the piston detached from the machine, it will only return about half way. If I attach the piston to the machine, it will stop on return with about 1 inch left before the top of the stroke.

I've read the threads about lubricating and loosening the collet due to sticking. The collet is not sticking on the machine. It is fully disengaged when the machine stops. I've bled all of the air from the lines. I've tried removing the hydraulic line when it is stuck, thinking maybe it was being hydraulic locked. No dice on that either. I've triple checked the valve, and it is fully open. The only thing I can think of is either the 2 springs in the piston are weak due to their age, or the new o-rings are too tight, even though they are an identical match to the o-rings that were in there.


I am having the same problem only when the machine is warm. Probally 200 shells in my ram is broken in though.


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Sat Feb 13, 2021 1:15 pm 
Crown Grade
User avatar

Joined: Sun Jun 24, 2018 2:51 pm
Posts: 2371
Location: S.E. Wisconsin
Faret wrote:
I am having the same problem only when the machine is warm. Probally 200 shells in my ram is broken in though.


MEC's H units return to the top of their stroke because of 2 springs. One in the cylinder and the center column spring. The in-line flow could have an effect on whether it makes it all the way "UP" because its a simple needle valve that the oil has to get past as it returns to tank.
So trouble shooting, open the needle all the way and test, be careful, it will go "DOWN" faster. If it does not go all the way "UP" disconnect the hydraulic cylinder from the clevis and see if the unit jumps "UP". If "yes" weak spring, I would replace the column spring first, its easier and you can get them from MEC.

Steve

_________________
The More Times You Pull The Trigger The More Fun You Are Having.
I repair MEC presses. PM me.
Used to be Steve Y


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Sat Feb 13, 2021 2:46 pm 
Field Grade

Joined: Thu Jun 04, 2020 7:05 pm
Posts: 49
HenryPeter wrote:
....I don't follow how you "flipped around an O-ring" or what you did. What prompted you to do that?
I ask to learn, not doubt.
H


They are high stability o-ring loaded u-cup seals, so not really an o-ring but I don't feel like typing that stuff out every time. Basically it's like a large square o-ring, with a smaller o-ring pressed into one side of it. This creates a flange. It may not be in the correct orientation right now, but it works so I'm not complaining.

For anybody that is interested, I will do a write up listing the parts you need to order and the assembly steps. I don't have any pictures for assembly/re-assembly, and I really don't feel like pulling my piston out again. If anybody would like to contribute pictures to make the write up more comprehensive, that would be great.


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Sat Feb 13, 2021 3:11 pm 
Field Grade

Joined: Thu Jun 04, 2020 7:05 pm
Posts: 49
YevetS wrote:
Faret wrote:
I am having the same problem only when the machine is warm. Probally 200 shells in my ram is broken in though.


MEC's H units return to the top of their stroke because of 2 springs. One in the cylinder and the center column spring. The in-line flow could have an effect on whether it makes it all the way "UP" because its a simple needle valve that the oil has to get past as it returns to tank.
So trouble shooting, open the needle all the way and test, be careful, it will go "DOWN" faster. If it does not go all the way "UP" disconnect the hydraulic cylinder from the clevis and see if the unit jumps "UP". If "yes" weak spring, I would replace the column spring first, its easier and you can get them from MEC.

Steve


Have you disassembled a piston before? Mine had 2 in the piston, so I want to make sure I have the correct information for my rebuild guide. The press is new to me, but the piston is 25 years old, so not sure if somebody else has modified it.


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Sat Feb 13, 2021 4:18 pm 
Crown Grade
User avatar

Joined: Sun Jun 24, 2018 2:51 pm
Posts: 2371
Location: S.E. Wisconsin
surgikill wrote:
They are high stability o-ring loaded u-cup seals, so not really an o-ring but I don't feel like typing that stuff out every time. Basically it's like a large square o-ring, with a smaller o-ring pressed into one side of it..


Its trade name is a loaded cup seal or loaded lip seal.

surgikill wrote:
This creates a flange. It may not be in the correct orientation right now, but it works so I'm not complaining.


The "flange" goes towards the pressure.

surgikill wrote:
Have you disassembled a piston before? .


No, I have not. I was shocked to find out the cylinder had an internal spring. Considering the OAL of the body and the stroke of the rod plus some thickness for the piston head leaves very little room for the spring before coil bind.

surgikill wrote:
Mine had 2 in the piston, so I want to make sure I have the correct information for my rebuild guide. The press is new to me, but the piston is 25 years old, so not sure if somebody else has modified it.


Call MEC

Steve

_________________
The More Times You Pull The Trigger The More Fun You Are Having.
I repair MEC presses. PM me.
Used to be Steve Y


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Sat Feb 13, 2021 11:53 pm 
Field Grade

Joined: Thu Jun 04, 2020 7:05 pm
Posts: 49
YevetS wrote:
surgikill wrote:
They are high stability o-ring loaded u-cup seals, so not really an o-ring but I don't feel like typing that stuff out every time. Basically it's like a large square o-ring, with a smaller o-ring pressed into one side of it..


Its trade name is a loaded cup seal or loaded lip seal.

surgikill wrote:
This creates a flange. It may not be in the correct orientation right now, but it works so I'm not complaining.


The "flange" goes towards the pressure.

surgikill wrote:
Have you disassembled a piston before? .


No, I have not. I was shocked to find out the cylinder had an internal spring. Considering the OAL of the body and the stroke of the rod plus some thickness for the piston head leaves very little room for the spring before coil bind.

surgikill wrote:
Mine had 2 in the piston, so I want to make sure I have the correct information for my rebuild guide. The press is new to me, but the piston is 25 years old, so not sure if somebody else has modified it.


Call MEC

Steve


Yea, I know the flange goes towards the pressure, however if I assemble it with the larger o-ring flange going towards the pressure, the piston will not function. :shock:


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Tue Feb 16, 2021 2:09 pm 
Field Grade

Joined: Thu Feb 21, 2019 2:06 pm
Posts: 21
YevetS wrote:
Faret wrote:
I am having the same problem only when the machine is warm. Probally 200 shells in my ram is broken in though.


MEC's H units return to the top of their stroke because of 2 springs. One in the cylinder and the center column spring. The in-line flow could have an effect on whether it makes it all the way "UP" because its a simple needle valve that the oil has to get past as it returns to tank.
So trouble shooting, open the needle all the way and test, be careful, it will go "DOWN" faster. If it does not go all the way "UP" disconnect the hydraulic cylinder from the clevis and see if the unit jumps "UP". If "yes" weak spring, I would replace the column spring first, its easier and you can get them from MEC.

Steve


Pulled my ram apart and it has the 2 springs inside all in good shape. They measured 9 1/4" long. I stretched them out to 10 1/2" long and all is working fine again. My ram was holding up the stroke of the press from going to the fully up position.


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Fri Feb 26, 2021 1:24 pm 
Tournament Grade
User avatar

Joined: Thu Oct 10, 2019 6:52 am
Posts: 177
I'm still hoping that the McMaster part numbers needed for the rebuild will be posted.


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Fri Feb 26, 2021 3:08 pm 
Crown Grade
User avatar

Joined: Sun Jun 24, 2018 2:51 pm
Posts: 2371
Location: S.E. Wisconsin
shacked wrote:
I'm still hoping that the McMaster part numbers needed for the rebuild will be posted.



Just look here

https://www.mcmaster.com/loaded-lip-sea ... p-seals-7/

Its pretty easy to figure out what you need.

Steve

_________________
The More Times You Pull The Trigger The More Fun You Are Having.
I repair MEC presses. PM me.
Used to be Steve Y


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Mon Mar 01, 2021 9:17 am 
Field Grade

Joined: Thu Jun 04, 2020 7:05 pm
Posts: 49
shacked wrote:
I'm still hoping that the McMaster part numbers needed for the rebuild will be posted.


Is there any way I can add a word document or a pdf here?


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Mon Mar 01, 2021 9:22 am 
Tournament Grade
User avatar

Joined: Thu Oct 10, 2019 6:52 am
Posts: 177
You can take screenshots of the doc and post them as images or alternatively take a photo of the doc and post that image.

If you want me to do this, PM me and I will provide you with my email address. You can then email me the doc and I will post the screenshots.


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Tue Mar 02, 2021 9:04 am 
Tournament Grade
User avatar

Joined: Thu Oct 10, 2019 6:52 am
Posts: 177
Here is the parts list:

http://imgur.com/a/X7hmfXy
Image

Per Surgikill, "you don't need 4 of those Dry-Running flanged sleeve bearings, I just bought 4 because they are fragile and I wasn't sure if I needed to modify it."


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Tue Mar 02, 2021 9:38 am 
Field Grade

Joined: Thu Feb 21, 2019 2:06 pm
Posts: 21
shacked wrote:
Here is the parts list:

http://imgur.com/a/X7hmfXy

Per Surgikill, "you don't need 4 of those Dry-Running flanged sleeve bearings, I just bought 4 because they are fragile and I wasn't sure if I needed to modify it."


Did you need 100 orings? :lol:


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 Post subject: Re: MEC 9000H Hydraulic Piston sticking
PostPosted: Tue Mar 02, 2021 11:52 am 
Crown Grade
User avatar

Joined: Sun Jun 24, 2018 2:51 pm
Posts: 2371
Location: S.E. Wisconsin
You can but the O-ring at any well stocked hardware store, use the same dash number. But one will most likely cost at least $1.00. Maybe Shacked can become the SGW O-Ring man and sell them like the member who sells index balls. LOL

Steve



_________________
The More Times You Pull The Trigger The More Fun You Are Having.
I repair MEC presses. PM me.
Used to be Steve Y


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