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Old 12-02-2022, 07:55 AM   #21
Mikendebbie
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This morning I tried a "bump" as described by dieselguy above. The slides are still out as we are not done loading up some stuff to the camper - so I have not run the slides for a couple of cycles yet. Just curious - do you do the "bump" everytime - 1 bump for the slides and 1 bump for the legs? Or is it 1 bump either place for "the system"?

Still - the two drivers side legs came back down. The one in front of the tires came down lower than before. Its still a bit dark but I need to look at those connections again to make sure there are no leaks. I will head to the store to get some more substantial straps to see if I can keep them up. Thanks for the suggestions and insight.

Dieselguy mentioned the "test port". That is where I saw some red fluid on the tip and some evidence of stain on the frame by the battery...not much stain...indicating that it has been a slow drip. What does that indicate?
 
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Old 12-02-2022, 08:27 AM   #22
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Originally Posted by Mikendebbie View Post
This morning I tried a "bump" as described by dieselguy above. The slides are still out as we are not done loading up some stuff to the camper - so I have not run the slides for a couple of cycles yet. Just curious - do you do the "bump" everytime - 1 bump for the slides and 1 bump for the legs? Or is it 1 bump either place for "the system"?

Still - the two drivers side legs came back down. The one in front of the tires came down lower than before. Its still a bit dark but I need to look at those connections again to make sure there are no leaks. I will head to the store to get some more substantial straps to see if I can keep them up. Thanks for the suggestions and insight.

Dieselguy mentioned the "test port". That is where I saw some red fluid on the tip and some evidence of stain on the frame by the battery...not much stain...indicating that it has been a slow drip. What does that indicate?
Some folks do not realize that with the Hyd leveler and hyd slides HYDRAULIC PRESSURE is what either keeps both Extended or Retracted.

There will be 2000 psi of pressure on the retract side even with the hydraulic pump not running after the slides and levelers are retracted.

I would have to do a bypass test on the drivers side (mid/rear) leveler legs. They are connected in tandem so if one is leaking internally it affects both.. IN your case either those two levelers have an issue or the Hydac valve for that side is not fully seating when the system is not running.. valves are held closed via spring pressure

The Test port drip shown in your picture is on the extend manifold block and there is another test port for the return side as well ( black lines ).. The test ports are where you hook up two psi gauges so that you can monitor system extend and retract pressures if you are troubleshooting certain issues.

I would cycle the leveling system another 5 times fully retracted and extended = 1 cycle.. Do Five cycles and pause after about every 2 cycles to let pump motor cool down.

Then retract and if the levelers slowly start extending when retracted do an internal bypass test on those two levelers .. very easy test if you have some basic skills

https://lci-support-doc.s3.amazonaws...cd_0001910.pdf

Regarding "Bumping" the system.. In 10 years on my current all hyd slides and six point hyd level up system I have never done this.. and it really does not pass my logic test.

There is a hydraulic pressure cutoff switch mounted on the return side manifold.. Its purpose is to kill power to the Hyd pump and Hydac solenoids if the system were to build excessive pressure ( about its cutoff limit )..
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Old 12-02-2022, 08:18 PM   #23
Mikendebbie
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Thankyou ChuckS!

Just to clarify a “cycle”…assume the rig needs to be hooked up to the truck - then fully retract all jacks - then manually run all jacks down to contact the ground a bit - then retract all jacks back up- right? That would be one cycle. This cycling does not use the auto level function - right?

Posting the pic below (never mind I can’t get the pic off my phone) so that others who attempt to strap the legs up will be aware. These straps were 1000 lbs heavy duty straps. My jacks still came down 2-3” and my pads bent into a U. Not sure how else I could have done it. Very curious if others have found a way to strap the thing up and NOT bend the feet. I will try to beat the pads back flat next week. I did call Lippert today while we drove and they set up a case number for me when I call them next week. They will help me run some tests. He mentioned I could “crack” the orange hose coupling (loosen a bit) to release pressure and the Jack might stay up. Anyway - we made it to our destination! I plan on strapping them back up if it still comes down after I run ChuckS cycle routine.
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Old 12-02-2022, 09:47 PM   #24
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There are a handful of us on the MOC that have hydraulic experience … I’m not here to bump heads with one another because our hydraulic backgrounds and experiences are all different. What works and has worked for me may not follow over to someone else. Hydraulic fluid for all intents and purposes cannot be compressed. No more than a hyd jack innards weighs, it shouldn’t take 2000 psi of pressure to keep it in place assuming there are no air pockets and no slow leaks past a seal or solenoid valve. I have gotten people a little farther down the road by my bumping theory more than once when in the end they had a piston seal issue. You build up pressure on say the retract side of the cylinder by laying on the retract button building up say 1800+ psi. Once you let off the button, that pressure can and will seep by a bad piston seal and in essence extend the cylinder while trying to equalize pressure on both sides of the piston. It happens … I’ve seen it. I’ve suggested the bumping of the hydraulic motor to in essence equalize pressures on both sides of the piston to keep the cylinder from walking out to get people a little farther down the road till adequate diagnostics can be more easily performed. I don’t know the exact issue here and haven’t said I did. Don’t promote the thought that I’m blowing smoke out my rear pockets. I may not have my head on straight here as I’m visualizing the valve on a front landing gear leg … If he has turned the solenoid valve setscrew clockwise in an effort to tighten it per previous conversation, hasn’t he manually opened that valve as if he were going to do a drill powered move? Does he not have to close that valve by turning the set screw counterclockwise to close the valve and put the system back in to standard operation?
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Old 12-03-2022, 06:29 AM   #25
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Dieselguy - I appreciate your input. I have lots of follow up questions from reading you and ChuckS posts.

As to turning the Allen head set screw - if you look at my first pic, I see 3 valves and the Allen head set screw is on the “bottom”. The wires on the middle valve were labeled (??? I can’t remember the text exactly but I knew the middle valve was for the drivers side rear jacks). It was dark when I started searching for an Allen wrench to fit the screw - so I have no idea what size it was…I found one that nicely fit. Then I tried applying pressure to turn it clockwise from the “upside down” perspective. The wrench did not move. I applied a bit more pressure. It still did not move. I tried applying pressure the other way (counterclockwise) it did not move. Since I have never done this - I was hesitant to apply anymore pressure either way.

I assume the clockwise motion from the “upside down” perspective was correct - right?

Also - I did not look on the top of each jack looking for an Allen set screw…should I do that? Or am I looking at the items in question up in the front compartment?

The first jack I noticed coming down was the drivers side rear jack…maybe 2” or so. Initially the mid-drivers side was staying up. After reading this thread about cycling to remove air - I entered manual mode and retracted and extended touching the RIGHT button a couple of times. I also used the REAR button to run all 4 jacks up and down a couple of times. Several minutes passed as I was doing other chores - and I noticed the drivers side mid jack was down about 3”-4” and the rear jack was down less - maybe 2”. That is when a dark cloud of dread and panic set in as I practiced my speech (in my head) to my wife for how we may not be able to make this trip if I can’t get these legs tied up. As evidenced by my pic - strapping the legs did not stop them from dropping to the same level as they did before I applied the straps. Even after I tied them up for the final attempt (after 5 or 6 attempts hooking the strap here then revising to try a better angle) I gave up and decided to make the trip with the legs down 3” to 4”. The mid jack is worse than the rear jack. The pic below is the mid rear jack. It came down further before we arrived and my foot pad is bent into a nice U shape.

Does the sequence of the jack failure described above add any info for diagnosis of the problem?
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Old 12-03-2022, 08:19 AM   #26
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Wishing you a sage trip and best of luck with your leveler legs.. The info in the link is the only way you will find out whether one of those two leveler legs is leaking internally.
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Old 12-08-2022, 06:45 AM   #27
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Lippert Jacks Falling - update

When I got the rig hitched up and ready to go home - ran the rear jacks up and down couple of times and observed drivers side rear jacks coming down about 1” - which was much less than they had come down previously. I put ratchet straps on both jacks and headed home.

Once we got home and had the RV backed into its spot, I started cycling the jacks (while I was still hooked up to the truck) as suggested by ChuckS (post #22 above)…I put the system into MANUAL MODE and ran five cycles with some rest in between to let the pump cool. A cycle included both front jacks and the four rear jacks extended until they all contacted the ground - then run them back up. I used the REAR button and the RIGHT and LEFT button running them up and down. Then I unhitched and ran auto-level. I retracted all 4 rear jacks to see if they would stay up or fall…and so far - all jacks are staying up!! It must have been an air bubble that developed over the year of inactivity and not exercising the jacks.

I learned my lesson! I will clean/wipe the legs and exercise them once or twice per month from here on out. I need to call Lippert and close the ticket. I still need to remove the feet and beat them back flat. The ratchet straps bent them into a deep U shape.

I appreciate all the help and advice!
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Old 12-08-2022, 07:31 PM   #28
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It’s good that you have things going your way with the cavet of “if it ain’t broke don’t fix it”. Help from any RV website on issues comes with the cost of simply educated “arm chair quarterback” suggestions because hands on diagnosis is best. I’m just going to ramble a bit here just because I’m still thinking about your particular experience. Your issue had very little to do with gravity and a “falling” jack as seen by your photo of the bowed landing gear foot … there was a definite pressure issue here … a leveler jack piston, rod, and foot just don’t weigh that much. Yes for the better part it probably had to do with air in the system, but knowing how a cylinder works in a hydraulic system I can’t completely figure out how the fluid came and went even with entrapped air as an issue. For a cylinder to move ... both fluid in and out has to happen whether it be extend or retract. Our cylinders are grouped in 2’s. Both fronts act together to level the unit front to back. Each side has 2 jacks mid and aft to level side to side. All 3 sets are controlled by their own solenoid valve(s). That can be proved by both your aft jacks extending on a given side. Another bothersome issue is you not being able to turn the solenoid valve set screw either way … is the valve super stuck open or is the set screw frozen in place … no matter if in your mind thinking upside down or actually facing the valve right side up, clockwise manually opens the valve and counterclockwise manually closes the valve. You did good by not trying to force the set screw. In the end all it is there to do is allow you to manually open the valve in case of hydraulic motor or 12 VDC power failure. Off to resting brain cells ...
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Old 12-08-2022, 08:03 PM   #29
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Originally Posted by dieselguy View Post
It’s good that you have things going your way with the cavet of “if it ain’t broke don’t fix it”. Help from any RV website on issues comes with the cost of simply educated “arm chair quarterback” suggestions because hands on diagnosis is best. I’m just going to ramble a bit here just because I’m still thinking about your particular experience. Your issue had very little to do with gravity and a “falling” jack as seen by your photo of the bowed landing gear foot … there was a definite pressure issue here … a leveler jack piston, rod, and foot just don’t weigh that much. Yes for the better part it probably had to do with air in the system, but knowing how a cylinder works in a hydraulic system I can’t completely figure out how the fluid came and went even with entrapped air as an issue. For a cylinder to move ... both fluid in and out has to happen whether it be extend or retract. Our cylinders are grouped in 2’s. Both fronts act together to level the unit front to back. Each side has 2 jacks mid and aft to level side to side. All 3 sets are controlled by their own solenoid valve(s). That can be proved by both your aft jacks extending on a given side. Another bothersome issue is you not being able to turn the solenoid valve set screw either way … is the valve super stuck open or is the set screw frozen in place … no matter if in your mind thinking upside down or actually facing the valve right side up, clockwise manually opens the valve and counterclockwise manually closes the valve. You did good by not trying to force the set screw. In the end all it is there to do is allow you to manually open the valve in case of hydraulic motor or 12 VDC power failure. Off to resting brain cells ...
Thanks for wording this perspective into something that makes sense DieselGuy. I'm in the same boat so to speak and have keep mum on the issue due to something I can't quite put my finger on making sense to me. Like you I'm fully cognizant of fluid on each side of hydraulic cylinders being of dissimilar values. 1500 - 2000 psi on one side of the cylinder to push the ram into the retract position should not be able to bleed across good or nominally serviceable piston seals to forcibly push the ram into an extend position as evident by Mike's foot pads getting bent U-shape while being strapped up. Hence your "bump down" suggestion to remove the trapped pressure on the retract side of the pistons. To me if the culprit is / was indeed an air bubble, to my way of thinking the air would have had to have been in the immediate vicinity of the solenoid valve.


I would say that I"m surprised manufacturers don't utilize counter balance valves across both lines, but due to the cost involved I guess them not doing so shouldn't surprise me at all. To me it is much the same analogy as disc versus drum brakes.



Last thought on the subject. There ARE ways to get 99.99% of the air out of hydraulic systems, but we both know that would involve a ton of work to accomplish.


Mike - very glad you were able to get your system back manageable again!
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Old 12-09-2022, 06:30 AM   #30
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Glad the cycling and bleed appears to have corrected you leveler leg creeping down issues.. I would still keep an eye on those to make sure you don't have an internal leak or a Hydac valve that isn't fully seating..

Remember the Hydac valves are (NC) Normally Closed and are held closed by internal spring pressure on the poppet valve inside the Hydac cartrdige.

I've been working on hydraulic systems myself for well over 45 years.. retired now.. The principles have not changed.

This video may help some folks get a better grasp on how their hydraulic leveler legs and hydraulic slide cylinders work

https://youtu.be/4REdJIW6-Kg
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