Disconnecting a Hydraulic Hose ???

[Carl n Susan]

I need to replace a leaking hose to my front left landing jack. My question is:

"What will happen when I disconnect the hose? Will the jack spew hydraulic fluid as the front of the RV drops down *OR* will the jack hold its pressure?"

I can hook the RV to the truck or support the front with cribbing if there will be a loss of fluid. If no spew, then no problem and I can just remove and replace the hose.

[Daryles]

I would jack it up and support the frame then retract the jacks.

Get caps and plugs before disconnecting the hoses so you have them ready to seal the hoses.

Double check this info:

Hydraulic
To cap the lines, fittings are 1/4" Female JIC 37° Flare.
Plug and cap Size for the JIC37 fittings ...
3404C-04 Cap
2408-08 Plug

[Foldbak]

If it's under pressure it's going to blow hyd fluid everywhere. Block the trailer and relieve pressure. It's still going to leak but won't be pressurized.

[scottz]

Just to be safe, I would definitely hook to the truck or use jack stands.

[Theunz]

With around 3,000lbs pin weight you will need some quality heavy duty jack stands. Be aware that a lot of cheaper jack stands are rated “per pair” and not each. Solid wood cribbing might be a safer method.

[432bartman]

When you do fix it, there is no need to bleed the system, as it will automatically do it.

[Carl n Susan]

Originally Posted by Daryles

Get caps and plugs before disconnecting the hoses so you have them ready to seal the hoses.

Double check this info:

Hydraulic
To cap the lines, fittings are 1/4" Female JIC 37° Flare.
Plug and cap Size for the JIC37 fittings ...
3404C-04 Cap
2408-08 Plug

Thanks Daryles! I have the plug ad caps in my spare parts stash. And the part numbers you supplied are dead on.

[Carl n Susan]

Thanks all! The RV is in my side yard behind a gate. To attach the truck (my plan) means it will sit out in the open. But I can move a couple of things and back the RV deeper into the yard so I can at least close the gate.

I figure I will retract the jacks and slides and maybe minimize fluid loss. It seems to me the hydraulic system is under pressure where the jacks/slides are in or out. But I will find out.

[Kyle and Lisa]

When I replaced hoses tied to a leveling leg, I take the pressure off that leg with a hydraulic jack, and then slowly release the fitting with plenty of rags to absorb the oil or a container if you have the room, and before you losing the fitting, put a block under the leg you are working so it does not drop down, causing more fluid flow.

[BB_TX]

Carl - I think you are right that when the hydraulic cylinders reac end of travel they will remain under pressure to hold in place whether slides are in or out. Same for jacks. If you could “bump” each individual cylinder in the opposite direction you might could relieve that pressure. But don’t know that is possible.

Alternately, if you know what that particular hose is used for you could relieve pressure on it by pressurizing the opposing hose, i.e. if leaking hose is to extend bedroom slide, then retract bedroom slide to pressurize the opposite hose.

But then I may be overthinking it.

[Playhouse]

Originally Posted by Carl n Susan

Thanks all! The RV is in my side yard behind a gate. To attach the truck (my plan) means it will sit out in the open. But I can move a couple of things and back the RV deeper into the yard so I can at least close the gate.

I figure I will retract the jacks and slides and maybe minimize fluid loss. It seems to me the hydraulic system is under pressure where the jacks/slides are in or out. But I will find out.

If you hitch up instead of using jack stands, just beware that your trailer is now permanently attached to your truck until you fix your jacks.

[ColoradoKampers]

Carl,
I did more than my share of hydraulic work on the former rig. It all depends on which hose you're replacing. On my 2020, I had red/orange and black hoses. The red/orange are extend. If you retract all hydraulics the extend lines are no longer under pressure. Removing the red/orange you'll get a rag full of hydraulic fluid, but no more. I just blocked the front up high so I could retract all the way and not be too far out of level. I didn't want to use my truck in case I needed more parts!

As for a black line, I had a tech remove one of those when everything was retracted and he ended up with a lot of fluid on the ground. I later talked with Lippert and they said that we should have extended everything to keep from loosing fluid from the black hose. However, I never confirmed this - so for what it's worth. I can tell you that even when we removed the black line, there was no explosion of fluid - just a lot leaking for a long time!

[Kyle and Lisa]

Originally Posted by ColoradoKampers

Carl,
I did more than my share of hydraulic work on the former rig. It all depends on which hose you're replacing. On my 2020, I had red/orange and black hoses. The red/orange are extend. If you retract all hydraulics the extend lines are no longer under pressure. Removing the red/orange you'll get a rag full of hydraulic fluid, but no more. I just blocked the front up high so I could retract all the way and not be too far out of level. I didn't want to use my truck in case I needed more parts!

As for a black line, I had a tech remove one of those when everything was retracted and he ended up with a lot of fluid on the ground. I later talked with Lippert and they said that we should have extended everything to keep from loosing fluid from the black hose. However, I never confirmed this - so for what it's worth. I can tell you that even when we removed the black line, there was no explosion of fluid - just a lot leaking for a long time!

I plug mine with a hydr. fitting as soon as I remove the hose, less leakage.

[Carl n Susan]

Thanks again for the suggestions/information.

The is a landing leg, not a slide. Of course it is the black (extend) hose fitting that leaks, So full retraction may not be ideal?

I will put a jack under the landing leg to prevent it from dropping down when the hose gets disconnected.

I have a 6 ton hydraulic jack and a 3 ton floor jack I could use (with cribbing) to support the front of the RV during the changeover. But my truck is really only used to tow the RV, has a much more secure connection with the hitch, and can be left attached for days with no issues. Other than having to move the RV off the pad and onto my back lawn, the truck seems to be a better choice in my case.

I do have plugs and caps to seal off the fittings when the time comes. That should help minimize fluid loss.

[ColoradoKampers]

Carl,
I think you are on the right track. The black hose powers retraction, so fully retracted jacks will have full pressure and lots of leakage. If I was doing it, I’d hitch up, and then extend until you have at least some of the weight off of the hitch. That should reduce the pressure in the retract side. There’s a control valve on the driver side jack that opens and closes the extend line. This will be closed (normal position unless you’re leveling), so you shouldn’t get much movement or leakage when you pull the black hose. Keep some rags handy and let me know if this theory pans out. 😊