Fluid, bleeding and leaks

A hydraulic room is only as good as the oil in it: the right fluid, checked with everything retracted, with no air and no leaks. Most slow and creeping rooms get fixed right here.

The short version

• Lippert and Equalizer run ATF (Dexron III; Lippert also allows Mercon 5). HWH wants its own oil, with Dexron as the fallback.
• Check and fill only with every room and jack fully retracted, or it overflows on the next retract.
• Air comes out by cycling: full travel both ways, let the foam settle 15 to 20 minutes, top off, repeat.
• A dropping level is an outside leak. A full tank with a weak or creeping room is an internal bypass.
• HWH hose ends: no thread tape or sealant, and tighten by flats, not by feel.

What goes in the tank

Use what the maker of that power unit specifies, and don't mix in whatever is on the shelf. HWH oil is clear, which makes a leak easier to clean up; red ATF can stain when it leaks. Lippert says change the fluid every 36 months.

Checking the level

Check only with every room and jack fully retracted. Lippert's combined manual warns that filling with anything extended can overflow the reservoir when it retracts, because the oil in the cylinders comes back to the tank. On a fifth wheel that includes hydraulic landing gear and stabilizers.

Getting the air out

Air makes a room spongy, slow and prone to creep, and Equalizer calls it the leading cause of rooms drifting out. Lippert's slide systems are self-purging: cycling 2 to 3 times pushes the air back to the reservoir and out the breather. If the tank is foamy, wait 15 to 20 minutes for it to settle before you purge again.

1. Retract everything, check the level and foam, and top off if needed.
2. Class A (Lippert): extend the jacks fully, extend every room, then immediately retract the rooms, then the jacks.
3. Fifth wheel (Lippert): landing gear down to the ground, stabilizers down to the ground, rooms out, then rooms in, stabilizers up, landing gear up.
4. Equalizer rooms: run each room fully out and hold the switch 10 to 15 seconds, let it settle 15 to 20 minutes, then run it fully in and hold 10 to 15 seconds.
5. Check for foam, top off with everything retracted, and repeat until it's gone.

Careful: Don't purge a fifth wheel unless the front is safely supported. The class A purge lifts the coach off its tires, so nobody goes under it.

Finding the leak

If you keep adding oil, it's going somewhere. Clean the power unit, fittings and cylinder ends, run the rooms, and look for fresh wet film. A dirty, oily film around one fitting usually marks the leak. Lippert's chart for a drifting room starts with tightening fittings and inspecting the hoses, fittings and power unit.

No oil on the ground but the room is weak or creeps: the leak is internal, past a piston seal or a valve seat. Use the cylinder bypass test from the diagnosis lesson to split cylinder from valve. Check the rods too: Equalizer warns overspray or undercoating on a rod flakes into the cylinder and damages the seals.

Hose and fitting work

HWH's hose rules are worth knowing on any system. Hose ends are swaged, not crimped. Never put Teflon tape or thread sealant on a hose end. Tighten a new hose swivel finger tight plus 2 flats (1/3 turn) and a reused one only 1 to 1 1/2 flats (about 1/4 turn); more damages the flare and makes it leak. HWH hose is rated to about 180°F of constant heat, so keep it off hot parts.

Cap every open line and port as soon as it's apart, and keep dirt out of the reservoir while you fill. Mark which hose goes to which port before you pull them; Lippert's bed slide uses orange and black hoses for the two sides, and Equalizer says to call its tech desk before changing plumbing because correctly plumbed rooms can move in different directions by model.

After the repair, refill, purge, and recheck the level with everything retracted after a couple of full cycles.

On the job

1. Retract every room and jack fully before you look at the tank.
2. Check the level against that maker's mark and look for foam.
3. Confirm what's in the tank matches the maker's fluid spec.
4. Clean and inspect the power unit, hoses, fittings and cylinder ends.
5. Fix the leak, cap open lines, and refill with the right fluid.
6. Purge by the maker's sequence and repeat until there's no foam.
7. Recheck the level with everything retracted after two full cycles.

Numbers

• Fluid change: Every 36 months (Lippert combined leveling and slideout)
• Foam settle time: 15 to 20 minutes (Lippert bed slide, Equalizer)
• Self-purge: 2 to 3 full cycles (Lippert through-frame hydraulic)
• Bleed hold at each end: 10 to 15 seconds (Equalizer rooms)
• Hose swivel: New: finger tight plus 2 flats (1/3 turn). Reused: 1 to 1 1/2 flats, about 1/4 turn (HWH)
• Hose heat rating: About 180°F constant (HWH hose)
• Cold threshold: Below 10°F (Lippert ATF systems)

Shop tip

With everything retracted and the level right, put a strip of tape at the oil line on the reservoir and date it. Next visit you'll know in two seconds whether it's losing oil.

Where this comes from

• Lippert (LCI), Electronic/Hydraulic Leveling and Slideout System Owner's Manual, Rev 07.14.2014, pp. 3, 27, 29
• Lippert, Hydraulic Through Frame Slide-out System Owner's Manual, CCD-0001616 Rev 11.14.19, p. 6
• Lippert, In-Frame Low Profile Slide-Out Owner's Manual, CCD-0001599 Rev 07.12.18, pp. 4, 5, 11
• Lippert, Level-Up Aftermarket Manual, Rev 09.15, p. 11
• HWH, Hydraulics and HWH Systems (training text), sections 4-4 and 4-5
• HWH Operator's Manual, hydraulic fluid section (Tiffin Motorhomes knowledge base)
• Equalizer Systems, Auto-Level and Slide-Out Operation Guide (April 2009); Slide-Out Drifting troubleshooting guide