Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. Today he discusses hydraulic jacks that won’t lift.
Dear Dave,
I have a 2007 Itasca Sunova with a Kwikee Level Best system. I added a little more than 1/2 quart of Dexron III and now the jacks operate very slowly and not all together. When they are finally all down, they will not lift the unit. —Roy
Dear Roy,
Typically when hydraulic jacks are acting erratically, it could be air in the line, debris in the fluid and screens, or a bad seal/bypass valve. I contacted Lippert Customer Service and Jason was kind enough to send me the service manual for this system as well as other helpful documentation. Lippert bought Kwikee a few years ago and they have an outstanding Customer Service Department.
Check the pressure in the lines of the hydraulic jacks
The first step would be to check the pressure in the lines. It should be between 1500-1800 psi. Since you had to add 1/2 quart of fluid, I would start with bleeding the lines. First, check to make sure all fittings on the manifold and cylinders are tight. With the cylinders fully retracted, fill the reservoir. Here is the procedure listed in the service manual.
1. Turn the system on and, using the control panel, extend one jack that is the farthest away from the pump. If air is in the system, the valves at the manifold will not seal and the cylinders will extend erratically. As the hydraulic fluid begins to purge the air from the system, the valves will seal and the jack should start to act independently.
2. When the reservoir begins to run low on fluid the resistance of the fluid within the pump lessens and the sound of the pump increases in pitch. When this happens, retract the cylinder and replenish the fluid in the reservoir.
3. Continue to extend the cylinder until it reaches the end of its stroke, then follow by retracting all of the cylinders. With air in the lines, the cylinders will emit squeaking and humming noises and move in a jumpy manner; as air is purged from the system the cylinders will move in a smoother, quieter manner. It may be necessary to extend and retract each cylinder several times to completely purge the lines and cylinders of air.
4. When the system has been bled fully, retract all of the cylinders and check the fluid level in the reservoir. With all cylinders retracted the fluid level should be within 1” of the top of the reservoir at the fill opening.
By-pass valve controls the pressure
The by-pass valve is located on the side of the mounting block on the pump and controls the pressure. The Lippert tech recommended checking the pressure. The diagram below shows the procedure.
It could also be debris in the fluid as seals can deteriorate and hydraulic fluid can become compromised. If you would like to tackle this yourself, I would suggest contacting Lippert Customer Service to get a thorough walk-through. I have attached the service manual pdf on the forum site which is linked below.
You can contact Lippert here:
customerservice@lci1.com
432-LIPPERT (432-547-7378)
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