Replacing a hydraulic jack. Pressure?

[CactusJuice]

I have been having a problem with jacks down msg for quite some time. I believe it is related to a slight loss of pressure to a leak while jacks are in the retract position. Inspection reveals a dirty oil film on one jack pad and the same around a fitting and top of jack. It could be hose, could be the jack, but either way I have to crack the system to fix. (my luck is it's the jack, so I am studying up on how to replace it)

It appears from the literature that the retract hose has 2k or so psi when in the retract position. I can't find anything about the extend side pressure.

My question is this: How does one go about relieving the system pressures before opening the hose fittings to remove the jack?

[chunker21]

In my opinion you need to google/search for the installation manual for the leveling system you have and follow that advice. Relying on social media and forums could get you hurt.

[lwmcguire]

Several threads here on the pressure sensor failure and hydraulic leveling systems

Download the appropriate manual from Lippert or OEM

Threads on IRV2 also on troubleshooting

No external leaks?

Any jack lowered when getting the error?

It can be an interal o-ring leaking

As noted, proceed safely using documented precautions

[Beau388]

Originally Posted by CactusJuice

I have been having a problem with jacks down msg for quite some time. I believe it is related to a slight loss of pressure to a leak while jacks are in the retract position. Inspection reveals a dirty oil film on one jack pad and the same around a fitting and top of jack. It could be hose, could be the jack, but either way I have to crack the system to fix. (my luck is it's the jack, so I am studying up on how to replace it)

It appears from the literature that the retract hose has 2k or so psi when in the retract position. I can't find anything about the extend side pressure.

My question is this: How does one go about relieving the system pressures before opening the hose fittings to remove the jack?

The retracting pressure runs about 600 psi depending on the size of the ram. The electric pump shuts-off at 1,500 psi and turns on if the pressure drops to 1,100 to 1.200 psi. The extend pressure will vary depending on the load the pair of jacks is lifting. For motor coaches, there are four current available ram (jack) sizes. The most common is the 9,000 lb size. The pump is capable of 3,500 psi but seldom needs more the 2,000 psi if the jacks are properly sized for the coach and the coach is not overloaded.
As far as breaking into the lines - manually ground the jacks and then start thew retraction sequence after about 5 seconds stop the retraction sequence. Next,trip the 100 amp CB in the house battery compartment and then I would disconnect the motor from the solenoid. There will be only a small pressure of about 100 psi remaining in the return lines and the extend lines should have no pressure in the lines. Prepare for gravity to cover you in fluid when you crack the fittings.

[Jimbo56]

Originally Posted by CactusJuice

I have been having a problem with jacks down msg for quite some time. I believe it is related to a slight loss of pressure to a leak while jacks are in the retract position. Inspection reveals a dirty oil film on one jack pad and the same around a fitting and top of jack. It could be hose, could be the jack, but either way I have to crack the system to fix. (my luck is it's the jack, so I am studying up on how to replace it)

It appears from the literature that the retract hose has 2k or so psi when in the retract position. I can't find anything about the extend side pressure.

My question is this: How does one go about relieving the system pressures before opening the hose fittings to remove the jack?

I’m experiencing a similar issue with my level up system. However I have no external fluid loss. I called LCI’s tech support. My call was answered immediately by a knowledgeable human. He walked me thru several checks while in a grocery store parking lot. He ended up determining that I have an intermittent pressure leak. 2 different rams have experienced this same issue. He was supposed to email me the pressure check instructions. I never got that email. But he did tell me that with the jacks retracted, if I loosened the orange retract line and saw fluid, I had a problem. He also told me not to watch a YouTube video involving a 5 th wheel as they art completely hosed opposite of a motorhome. For a MH, orange is retract, black is extend. Since we’re on a 12 week trip, and the leak down doesn’t occur consistently, I’m just keeping my fingers crossed and haven’t tried a test yet.

[lwmcguir]

Originally Posted by Beau388

The retracting pressure runs about 600 psi depending on the size of the ram. The electric pump shuts-off at 1,500 psi and turns on if the pressure drops to 1,100 to 1.200 psi. The extend pressure will vary depending on the load the pair of jacks is lifting. For motor coaches, there are four current available ram (jack) sizes. The most common is the 9,000 lb size. The pump is capable of 3,500 psi but seldom needs more the 2,000 psi if the jacks are properly sized for the coach and the coach is not overloaded.
As far as breaking into the lines - manually ground the jacks and then start thew retraction sequence after about 5 seconds stop the retraction sequence. Next,trip the 100 amp CB in the house battery compartment and then I would disconnect the motor from the solenoid. There will be only a small pressure of about 100 psi remaining in the return lines and the extend lines should have no pressure in the lines. Prepare for gravity to cover you in fluid when you crack the fittings.

Thanks Beau,

My method of cracking a hydraulic line is to wear safety equipment, safety glasses and be sure to face the line so if you get sprayed it hits the glasses, not behind them, put the flare wrench on the fitting and the back up wrench. Then cover both with a red rag, then slowly loosen the fitting. A basin below with adsorbent is good as well.

[MJC62]

Originally Posted by lwmcguir

Thanks Beau,

My method of cracking a hydraulic line is to wear safety equipment, safety glasses and be sure to face the line so if you get sprayed it hits the glasses, not behind them, put the flare wrench on the fitting and the back up wrench. Then cover both with a red rag, then slowly loosen the fitting. A basin below with adsorbent is good as well.

May I make one suggestion? Besides the safety glasses get yourself a flip up face shield. It has saved me from injury on a couple occasions. Once on a job the angle grinder I was using the wheel disintegrated and the shield kept the debris out of my face. Another time it was brake fluid when changing a caliper hose.

[Jimbo56]

Originally Posted by CactusJuice

I have been having a problem with jacks down msg for quite some time. I believe it is related to a slight loss of pressure to a leak while jacks are in the retract position. Inspection reveals a dirty oil film on one jack pad and the same around a fitting and top of jack. It could be hose, could be the jack, but either way I have to crack the system to fix. (my luck is it's the jack, so I am studying up on how to replace it)

It appears from the literature that the retract hose has 2k or so psi when in the retract position. I can't find anything about the extend side pressure.

My question is this: How does one go about relieving the system pressures before opening the hose fittings to remove the jack?

According to the LCI guy I talked to on the phone, with jacks retracted, crack the orange retract line, if any sign of fluid, that indicates your fluid is bypassing and going back to the reservoir. Or in other words, an internal leak. While retracted, and the seals holding pressure, no fluid should run out of that line.

[Geterdun]

Originally Posted by Jimbo56

According to the LCI guy I talked to on the phone, with jacks retracted, crack the orange retract line, if any sign of fluid, that indicates your fluid is bypassing and going back to the reservoir. Or in other words, an internal leak. While retracted, and the seals holding pressure, no fluid should run out of that line.

Isn't the retract line the one that supplies pressure to retract and hold the jacks up? It should always be pressurized when the jacks are up or you'll get a "Jacks Down" alarm and the pump will run to pressurize the line if driving.

[Jimbo56]

Originally Posted by Geterdun

Isn't the retract line the one that supplies pressure to retract and hold the jacks up? It should always be pressurized when the jacks are up or you'll get a "Jacks Down" alarm and the pump will run to pressurize the line if driving.

According to the LCI guy, it has “suck” pressure. Therefore if fluid is leaking out of the retract line fitting, it is bypassing that seal and not sucking.

[Geterdun]

Originally Posted by Jimbo56

According to the LCI guy, it has “suck” pressure. Therefore if fluid is leaking out of the retract line fitting, it is bypassing that seal and not sucking.

The floor sweeper must have answered your call. There is no "suck pressure" in a hydraulic leveling system.

[Jimbo56]

Originally Posted by Geterdun

The floor sweeper must have answered your call. There is no "suck pressure" in a hydraulic leveling system.

Congratulations ! I see you have the Thor Forum degree. So I guess the janitor walked me through an hour and a half of system checks just for the hell of it. Since you seem to know more than any of the tech support guys (and based on some of your other less than nice comeback posts) I’ll leave this one to you. Mee personally, I’ll listen to the LCI folks. Good bye

[Geterdun]

Originally Posted by Jimbo56

Congratulations ! I see you have the Thor Forum degree. So I guess the janitor walked me through an hour and a half of system checks just for the hell of it. Since you seem to know more than any of the tech support guys (and based on some of your other less than nice comeback posts) I’ll leave this one to you. Mee personally, I’ll listen to the LCI folks. Good bye

"Suck pressure" is an oxymoron. You either have pressure - which is the basis of any hydraulic system; or vacuum - which no hydraulic system relies on as the most pressure a vacuum can generate is 15 PSI from ambient air pressure, which is not applied to any cylinder in the LCI leveling systems.

I suspect it's a "telephone game" problem, so as long as it makes sense to you.

[lwmcguire]

Hydraulic cylinders have the extend port on the base mount and the return is on the rod extension end.

The same flow/pressure is applied, extending and retracting. Difference is in controls only or limit switches that control power to the pump.

[CactusJuice]

Originally Posted by Jimbo56

Congratulations ! I see you have the Thor Forum degree. So I guess the janitor walked me through an hour and a half of system checks just for the hell of it. Since you seem to know more than any of the tech support guys (and based on some of your other less than nice comeback posts) I’ll leave this one to you. Mee personally, I’ll listen to the LCI folks. Good bye

The test you described above is for jacks. It determines whether the jack is internally leaking. That condition would allow the jacks to drift down or not hold weight over a period of time (what mine does).

The confusion may be in the color of the hoses. On mine the retract is orange and extend black. I have read that that is not always the case.

The test, per Lippert troubleshooting guide is: Retract the jacks, crack the EXTEND line, repeatedly press retract on the control panel and look for fluid coming from the EXTEND port of the jack that was just opened. If it does, bad jack.

I visited my RV today and wiped all the film/dirt off the jack I suspect. It does not actually look like the jack or the hoses are leaking. Repeated operation shows no fluid coming out anywhere. What it does look like is oil slopped while filling the spout during oil changes that gone blown onto the jack, the frame next to the jack etc.

Anyway looks like I will be doing the internal leak test. Ugh. This is the first RV I have owned that had levelers and I thought that was cool. But they are more hassle than they are worth, IMO.

[lwmcguire]

Try a quart of Marvel Mystery fluid or some Fork oil. Cat and others also have hydraulic seal products.

It might help the offending o-ring to seal and not allow flow by

[chunker21]

Originally Posted by lwmcguire

Try a quart of Marvel Mystery fluid or some Fork oil. Cat and others also have hydraulic seal products.

It might help the offending o-ring to seal and not allow flow by

What you are referring to is anti-stiction additive. Lippert recommends the following;
1. Torco RFF Grade 15
2. Maxima Fork Oil Grade 15
3. Caterpillar Hydraulic Oil Additive 1U-9891

https://manuals.heartlandowners.org/...%20Systems.pdf


I have popping in mine and will be adding the Maxima oil when I do my annual servicing. I also have a left front jack that "sags" and I'm hoping that helps that issue too. By sag it lowers 2-4" when retracted and has happened while driving. That sets off alarms but hitting "retract all" brings it back up. Freightliner S2RV with EQ Smart Level system. Sagging is intermittent

[lwmcguir]

Originally Posted by chunker21

What you are referring to is anti-stiction additive. Lippert recommends the following;
1. Torco RFF Grade 15
2. Maxima Fork Oil Grade 15
3. Caterpillar Hydraulic Oil Additive 1U-9891

https://manuals.heartlandowners.org/...%20Systems.pdf


I have popping in mine and will be adding the Maxima oil when I do my annual servicing. I also have a left front jack that "sags" and I'm hoping that helps that issue too. By sag it lowers 2-4" when retracted and has happened while driving. That sets off alarms but hitting "retract all" brings it back up. Freightliner S2RV with EQ Smart Level system. Sagging is intermittent

Thanks Chunker

Another benefit of the additives is reducing the slippage when jacks are extended which creates the sound many hear and wonder what it is.

[CactusJuice]

Is there any relationship between a jack that drifts and a problem at the specific jack? Put another way, if one jack drifts or won't hold weight, does that mean it is THAT jack that could have internal leak?

In the retract position, all jacks are hydraulically connected and would, I think have the same pressure. So a jack drifting down would not indicate a problem with that jack. Could be any of them.

But in extend, they have separate valves so maybe failing to hold in that position is diagnostic of a problem with that jack or that valve?

[chunker21]

Originally Posted by CactusJuice

Is there any relationship between a jack that drifts and a problem at the specific jack? Put another way, if one jack drifts or won't hold weight, does that mean it is THAT jack that could have internal leak?

In the retract position, all jacks are hydraulically connected and would, I think have the same pressure. So a jack drifting down would not indicate a problem with that jack. Could be any of them.

But in extend, they have separate valves so maybe failing to hold in that position is diagnostic of a problem with that jack or that valve?

A single jack that won't stay up is likely an internal leak in that jack. I've seen different comments whether the jacks are rebuildable or not.