743 Spool Leak -

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theNEWT

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Joined
Mar 16, 2012
Messages
23
Hi Folks My 743 sprung a massive hydraulic leak at the boom up/down spool (top spool - left hand pedal). I have removed the spool and found that the screw that connects the spool with the rear spring assembly has sheared off. Possibly this resulted in the seal failure..not sure. I can only see one o-ring on the spool after removing it and it basically looks like an o-ring, it doesn't at all look like a quad-ring. I'm told by parts suppliers that it should have 2 quad-rings....is this true, when I can only see one o-ring? If I do need to add the rear quad-ring, is it best to add it from the front after the spool is replaced, I can't imagine it would push through. I have not removed the cast alloy cover with the circlip. Should I to check the balls/springs? Thanks for any help/advice.
 

Tazza

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Dec 7, 2004
Messages
16,829
It is a quad ring, one front, one back.
What screw broke off? The bolt that holds the spring to the spool rod? weird bolt to break.
The way to install the Orings is to pull the rod out the back, you may need to bend the lift/tilt tube lines to get it out.
Be sure to drain all the fluid you can before you sart, or it will all leak out the spool hole.
I'd check the detent balls, you are in this far, may as well finish it.
 
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theNEWT

Member
Joined
Mar 16, 2012
Messages
23
It is a quad ring, one front, one back.
What screw broke off? The bolt that holds the spring to the spool rod? weird bolt to break.
The way to install the Orings is to pull the rod out the back, you may need to bend the lift/tilt tube lines to get it out.
Be sure to drain all the fluid you can before you sart, or it will all leak out the spool hole.
I'd check the detent balls, you are in this far, may as well finish it.
Thanks Tazza. Yes, it's the screw between the spool rod and the spring assembly....only screw in there I think. Anyway, at the moment it's at the engineers for screw removal, I don't want to risk damaging the spool rod myself. The engineer said he will disassemble the detent housing, so I'll check the balls when it's back. I have the new parts including quad rings and replacement screw. It's very odd seeing the shaft only had one oring seal. It has never leaked at the front, but pretty sure it had been leaking at the rear. Wait for the spool to be finished and I'll put it all back together.....it was very difficult removing the front connecting pins....but I managed it. Thanks for your help. I'll see how the two seals go. Cheers
 

Tazza

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Staff member
Joined
Dec 7, 2004
Messages
16,829
Thanks Tazza. Yes, it's the screw between the spool rod and the spring assembly....only screw in there I think. Anyway, at the moment it's at the engineers for screw removal, I don't want to risk damaging the spool rod myself. The engineer said he will disassemble the detent housing, so I'll check the balls when it's back. I have the new parts including quad rings and replacement screw. It's very odd seeing the shaft only had one oring seal. It has never leaked at the front, but pretty sure it had been leaking at the rear. Wait for the spool to be finished and I'll put it all back together.....it was very difficult removing the front connecting pins....but I managed it. Thanks for your help. I'll see how the two seals go. Cheers
There will be one quad ring at the front, one at the other end, there should eb a grooe in the housing for it to fit into from memory.
I hope they don't have too much trouble removing the broken bolt, i have never seen one break.
 
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