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4840 blowing o-rings....Gman help!

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scottAR

03-13-2003 19:05:54




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On a recently purchased 4840, I changed the hydraulic couplers from JD taper to ISO. Been pulling a large landplane and in about two hours the small oring on the shutoff shaft will start leaking. Replaced orings and backup rings then in about two more hours it started leaking again. Changed hoses over to the other set of couplers and in about two hours it started leaking. It is always on the return line not the lifting side. What is happening or what am I doing wrong?

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WTW

03-14-2003 14:18:10




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 Re: 4840 blowing o-rings....Gman help! in reply to scottAR, 03-13-2003 19:05:54  
Scott, HTR has got the most likely solution to your problem. To install the pin in your lever the valve shaft has to be pushed down against spring to align the hole in lever and shaft. This is common that the lever are installed installed upside down and is easily corrected. DW



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scottAR

03-14-2003 17:40:23




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 Re: Re: 4840 blowing o-rings....Gman help! in reply to WTW, 03-14-2003 14:18:10  
It took me a while but I think I understand. I probably have all four cut off handles with the roll pin in them installed upside down. on the last one it popped the "freeze" plug out and I noticed that spring was not compressed but did not know why. Thanks guys



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G-MAN

03-14-2003 17:18:54




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 Re: Re: 4840 blowing o-rings....Gman help! in reply to WTW, 03-14-2003 14:18:10  
I've got to say that I am completely confused by the last two posts? What pin and lever are you referring to? I rebuilt two 4640 SCVs just the other day and don't know what pin and lever you're talking about. If you're talking about the lever that turns on flow to the hoses at the coupler, every one I've ever seen is retained in the coupler barrel by a C-clip, not a pin. I'm also curious which lever can be installed upside down. Those levers can only go from the bottom up. There's a flat on the top of the barrel for the spring to rest on. I'm not trying to start any b.s. or anything else. I'm honestly confused? Maybe I'm missing the forest for the trees here. Are you possibly referring to the flow-control lever? There is no spring behind the valve. If he's got the knobs on the valves upside down, that's going to severely limit the flow (I've had one on wrong before), but it didn't cause a leak. If that's the case, the opening on the flow control valve should be toward the left when the knob is in the upright position.

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HTR

03-14-2003 19:37:12




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 Re: Re: Re: 4840 blowing o-rings....Gman help! in reply to G-MAN, 03-14-2003 17:18:54  
This problem only occurs when converting the old style JD break away coupler to the ISO coupler. When converting to the International standard orgination (ISO) coupler, you discard the old barrels and the one piece leaver and shaft, that opens and closes the balls in the barrels. The new lever and shaft is a two piece deal, and the lever is held on the bottom of the shaft with a roll pin. The new shaft that goes through the barrel has a Oring groove that seals in the top of the barrel instead of the O ring groove in the top of the barrel where the flat is. The shaft has to be installed from the top of the coupler, and the lever put on the bottom of the shaft, and is held on by a roll pin. The lever has a raised part that seats in the little notch in the bottom of the coupler housing to help hold the lever in open or closed position, the same as the old one piece lever. If the lever is installed with the raised part down, the oil pressure will force the shaft up far enough for the Oring to come out of the top of the barrel. If the lever is installed right side up, the pressure raising the shaft only locks it tighter in the open position.

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G-MAN

03-15-2003 07:32:14




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 Re: Re: Re: Re: 4840 blowing o-rings....Gman help! in reply to HTR, 03-14-2003 19:37:12  
Thanks for clearing that up - I just couldn't figure out what you guys were talking about, lol. I haven't had to swap the old boxes to the new couplers yet. The old JD tips and couplers are still real popular around here.



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HTR

03-14-2003 09:24:06




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 Re: 4840 blowing o-rings....Gman help! in reply to scottAR, 03-13-2003 19:05:54  
Check the two little levers on the shafts. One side of the lever is flat, and the other side has a raised portion. If the flat side, of the lever, is installed up, the shaft can move up far enough to come out of the Oring.



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G-MAN

03-14-2003 07:33:46




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 Re: 4840 blowing o-rings....Gman help! in reply to scottAR, 03-13-2003 19:05:54  
Have you tried replacing the tip o-rings and back-up rings with the quad-ring style? I would start there, and then maybe consider replacing the couplers themselves, as they may be worn enough to not allow the tips to seat firmly. That's not much info, but I'll do some more thinking and see what else I can come up with. It is odd that it is only on the return side.



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