Billybuck

Member
My 660 has been working hard lately getting ground sprayed and worked up for planting. While planting several acres of corn with a fairly heavy no-till planter, I noticed the lift was slowing down a bit. I finished up the corn, hooked up a disc, and it was bobbing (hiccups). I started working ground for sorghum. By the time I finished, the disk wouldn't raise enough to clear the ground. Fluid level is full.
Today, I pulled the piston pump plug and verified prime at the pump. With the disk hooked up, i removed the fill cap and watched the lift cylinder with a flashlight as I attempted to raise the disk with touch control. Oil sprayed from above and behind the cylinder in the area of the safety valve which I suspect is the culprit. This, if the only issue, would be the second safety valve failure in 12 years, the last being 6 or 7 years ago. Is that normal? I notice, despite living under shelter, the UC 134 fluid has become milky from condensation. Could that raise the pressure and blow the valve?
The FO-20 manual doesn't show and I don't recall a gasket between the lift cylinder and lift cover, just o'rings between accessory plate and cylinder. Is there a gap between the cylinder and lift cover at the location of the safety valve which allows fluid to discharge back to the sump as I observe, presumably oriented with the side holes in the safety valve? I think so from prior experience.
I am planning to pull the lift cover, drain the milky 134 fluid, rinse with kerosene, and replace the safety valve and accessory plate orings.
I would also mention when I first used the tractor this Spring, I had no lift as the pump had lost prime. I was able to get it primed by holding my thumb over the pump prime hole while cranking and all has been fine until now. Unrelated?
Stopping at CNH for parts in the morning and looking for confirmation on the path I'm taking. I have a lift cover gasket on hand from a prior entry when I tuned up the unit with Zane's jig, replaced the cam follower pin, etc..
 
(quoted from post at 23:39:32 06/06/19) My 660 has been working hard lately getting ground sprayed and worked up for planting. While planting several acres of corn with a fairly heavy no-till planter, I noticed the lift was slowing down a bit. I finished up the corn, hooked up a disc, and it was bobbing (hiccups). I started working ground for sorghum. By the time I finished, the disk wouldn't raise enough to clear the ground. Fluid level is full.
Today, I pulled the piston pump plug and verified prime at the pump. With the disk hooked up, i removed the fill cap and watched the lift cylinder with a flashlight as I attempted to raise the disk with touch control. Oil sprayed from above and behind the cylinder in the area of the safety valve which I suspect is the culprit. This, if the only issue, would be the second safety valve failure in 12 years, the last being 6 or 7 years ago. Is that normal? I notice, despite living under shelter, the UC 134 fluid has become milky from condensation. Could that raise the pressure and blow the valve?
The FO-20 manual doesn't show and I don't recall a gasket between the lift cylinder and lift cover, just o'rings between accessory plate and cylinder. Is there a gap between the cylinder and lift cover at the location of the safety valve which allows fluid to discharge back to the sump as I observe, presumably oriented with the side holes in the safety valve? I think so from prior experience.
I am planning to pull the lift cover, drain the milky 134 fluid, rinse with kerosene, and replace the safety valve and accessory plate orings.
I would also mention when I first used the tractor this Spring, I had no lift as the pump had lost prime. I was able to get it primed by holding my thumb over the pump prime hole while cranking and all has been fine until now. Unrelated?
Stopping at CNH for parts in the morning and looking for confirmation on the path I'm taking. I have a lift cover gasket on hand from a prior entry when I tuned up the unit with Zane's jig, replaced the cam follower pin, etc..
robably barking up wrong tree,as ram cylinder safety valve is simply a spring loaded ball and seat.....re-sets itself.
 
Hi Jesse. Your reply may explain why I've fixed this same issue in the past yet have a spare safety valve in my parts and inventory.
Spray is from above the cylinder and near enough to the fill hole you could stick a finger through the hole into the spraying oil.
I thought I solved this problem before without pulling the lift cover (safety valve/o'rings) but if there's a gasket between the cylinder and cover, that would be my suspect.
Is this said gasket?
mvphoto37320.jpg
 
Roger.
By the way, the carb on this tractor has been flawless since you removed that brass burr many moons ago. I just knocked on some wood!
 
(quoted from post at 08:16:03 06/07/19) Roger.
By the way, the carb on this tractor has been flawless since you removed that brass burr many moons ago. I just knocked on some wood!
reat!
 
Check for broken 7/16 studs holding the cylinder assembly to the lift chest possibly why the O'rings are leaking by
 
(quoted from post at 16:46:29 06/08/19) Thanks, I'll check that carefully.
Update- pulled lift cover, brought it home to workshop. Getting ready to separate lift cylinder from cover and decided to remove safety valve. Didn't think my deep socket was getting over the valve to loosen it. Turned out it was so loose I could turn the socket it with fingers. Suspect that's why and from where it was leaking. Concerned now, that dropping the cylinder to replace those o'rings may be unnecessary and lead to more risk of not getting them installed properly than it's worth. Working solo and I've had struggles with o'rings staying put in easier to assemble situations. Thoughts? All o'rings (cylinder and accessory plate) and new safety valve arrive tomorrow.
 
(quoted from post at 12:13:27 06/13/19)
(quoted from post at 16:46:29 06/08/19) Thanks, I'll check that carefully.
Update- pulled lift cover, brought it home to workshop. Getting ready to separate lift cylinder from cover and decided to remove safety valve. Didn't think my deep socket was getting over the valve to loosen it. Turned out it was so loose I could turn the socket it with fingers. Suspect that's why and from where it was leaking. Concerned now, that dropping the cylinder to replace those o'rings may be unnecessary and lead to more risk of not getting them installed properly than it's worth. Working solo and I've had struggles with o'rings staying put in easier to assemble situations. Thoughts? All o'rings (cylinder and accessory plate) and new safety valve arrive tomorrow.
se compressed air as substitute for hyd pressure and see what you have going on.
 
I can do that.
Wonder why the oring recesses aren't in the lift cover, where they'd be more inclined to stay on installation, rather than the accessory plate? If there's a reason it escapes me.
 
(quoted from post at 03:46:01 06/14/19) I can do that.
Wonder why the oring recesses aren't in the lift cover, where they'd be more inclined to stay on installation, rather than the accessory plate? If there's a reason it escapes me.

After reinstalling the safety valve and accessory plate, applying compressed air, the lift performs properly. The leak seen through the fill port originated at a hole which discharges into the rear of the void between the lift cylinder and lift cover, opposite the hole marked in the photo with the arrow, on the accessory plate. I still don't know if the safety valve discharges through the accessory plate to this location or not. I was not able to trace the path from the safety valve with a wire and the discharge area is too large to isolate with air. I was not able to interpret from the schematic in the manual of hydraulic cross section of the cylinder and accessory plate where the safety valve would discharge either.
I'm going to install a new safety valve and accessory o'rings and suspect the problem will be solved, given the results of the compressed air test.

mvphoto37799.jpg

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(quoted from post at 02:11:08 06/17/19)
(quoted from post at 03:46:01 06/14/19) I can do that.
Wonder why the oring recesses aren't in the lift cover, where they'd be more inclined to stay on installation, rather than the accessory plate? If there's a reason it escapes me.

After reinstalling the safety valve and accessory plate, applying compressed air, the lift performs properly. The leak seen through the fill port originated at a hole which discharges into the rear of the void between the lift cylinder and lift cover, opposite the hole marked in the photo with the arrow, on the accessory plate. I still don't know if the safety valve discharges through the accessory plate to this location or not. I was not able to trace the path from the safety valve with a wire and the discharge area is too large to isolate with air. I was not able to interpret from the schematic in the manual of hydraulic cross section of the cylinder and accessory plate where the safety valve would discharge either.
I'm going to install a new safety valve and accessory o'rings and suspect the problem will be solved, given the results of the compressed air test.

mvphoto37799.jpg

[/url]

I was wrong. On reassembly, I decided to tighten the cylinder to lift cover bolts a bit and one of the bolts passing through a dowel was mostly stripped and turns out also broken. The lift did function and would raise a disk though it was slow and I detected a slight hiccup. Looking through the fill port, leakage was still present though less than original inspection. I now suspect the broken bolt is allowing leakage around an o'ring or rings between the cylinder and lift cover.
Machine shop has the cylinder and will likely have to install a helicoil. One thing I am unable to find in any schematic (Messicks site) is a description of the length of the fine thread bolts holding the cylinder to the lift cover. Are they all the same length?
 

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