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Discussion Starter #1
We have an 2010 8120 combine that keeps blowing an O ring on a solenoid valve within the big brass valve block on the left side of the feederhouse. I've replaced it maybe 4-5 times and each O ring will last about 50 hours before it blows again. I know its a certain metric size and its not a terribly hard fix but does anyone have any ideas what would be causing this to happen? Its on the solenoid that controls the reel fore+aft on the bottom of the block. The sensor has a little torque sticker saying 4-6 ft lbs.
 

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Look for nicks, cracks, or obvious problems on the oring seat, valve or block. I believe I have changed that oring and don't remember it being metric. I used an oring from an aftermartket CAT oring kit. Similar to what most companies put out. Just the kit I have in my service truck.
The torque spec is fairly light to keep the valve from distorting and causing the spool to stick if you are wondering about that.
If went a little tighter on the torque and it doesn't stick but the oring holds might be worth a try. I doubt that would fix the problem. Make sure to have a little oil or grease on the oring when installing. I am guessing you have a burr or something for it to fail that consistently. Have a picture of the failed oring before you remove next time? Maybe a picture of the solenoid and block seats? Over pressuring the oring seems unlikely to me also.
 

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Might also be worth getting the o-ring from your dealership. In my experience the o-rings in the general kits don't hold up very well to the high hydraulic temperatures. Had an o-ring on my macdon swather that would blow out quite often. Finally got the OEM o-ring (which was a different color) and put it in, and haven't had any troubles since.
 

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Go get a O ring kit from a hydraulic supplier. Those cheap ones in the red case don't really fit anything. I think what would work in your application would be a ORB size. If you look it up on the parts store it might even tell you the durometer. I would post a link to the kit I have but I can't find it anywhere.
 

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Discussion Starter #5
So far the O rings i have used were from our local dealer. The parts diagram/breakdown they pull up on the computer wont say a specific size or type of O ring so i ordered a new valve that comes with them. It will be very hard to check for nic's or burr's because as soon as the valve is out you get a solid stream of hydraulic oil spewing out of the hole in the valve block. When the O rings have failed in the past you can see a little piece of rubber sticking out of the seated area its supposed to be in indicating that it has blown, along with a steady drip and even a small stream of oil shooting out.

And which is the torque setting for? The valve itself or the small electrical component that goes over it (that has the sticker on it)?
 

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The torque spec is for the nut holding the solenoid coil on the spool (valve) , NOT the spool in the block. Blowing orings is becoming more common as the pressures creep higher. If you can get a size (the best thing is the "dash" number, the CIH parts site used to have those listed, looked like -xxx) You can use the dash number or measurements to McMaster-Carr and get a whole bag of orings for what the one from the dealer is costing! They have all kinds of types, I would recommend looking into a Polyurethane or PTFE o-ring instead of the normal Buna-N oring for higher strength.
 

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Discussion Starter #7
So we started soybeans yesterday and so far in about 15-18 hours of combining i've blown through 3 more O-rings. I was able to track down the exact O-ring that corresponds with the parts breakdown at our local dealership with-in a seal kit and that one only lasted 5 hours! Another thing to note as well is the next "port" or valve down the line from the one that keeps blowing is the one that most recently blew. I'm thinking its not the O-rings themselves but another problem related to the hydraulic system and these are just the point of least resistance.

any thoughts?
 

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Not sure what to think now?
More than 1 is giving trouble?
Is the hydraulic pump closed centre?
Is it maybe not going into standby or the pump control is sticking or something.
 

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I think the monitor will give you some hydraulic pressures. I would check it with manual gauge. I would then pull that whole valve assembly off and have a hydraulic shop look at it for you. Could be a long harvest if you don't figure it out. Or just have a hydraulic shop come out and look at on the machine.


Here is a link to a bunch of case combine training info. Under 20 series is the 120 series service manual. Hope it helps.
 

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Did someone play around with the valve setting?
I had on a 8010 the hhc wasn't responding that good even if I turn up the sensitivity.
So I got the dealer turn the screw and Shortly after the o ring started to blow out.
 
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