Slideouts extend a few inches while being pulled

[Cindy and Ray's Grand Tour]

Our kitchen slide out (hydraulic) will extend a few inches at the bottom while we are driving down the road. It takes it about 100 miles to start to work out and gets further until I stop, enter the trailer and push the retract button. Then we are good for another 100. When it was in storage for 6 months, both the kitchen slide and the opposing dining room slide came out even further while sitting. I noticed that two other 5th wheels stored nearby had the same problem. Any idea what is causing this? Do others have the same issue? Is there an easy fix?

[twindman]

I had this problem on my new Mountaineer. Going to Goshen on first trip!
End up Lippert took it in and spent about 5 hours and replaced the cylinders on both slides. What took so long is they had to go to another city about 60 miles away to get them! I don't think they even checked them. They said usually the biggest slides are the problem, so just replaced. On the way home it happened again to a lessor degree, and my dealer just ran them in and out about 10 times to get the air out and no more problems in 6 years.
EDIT: I was just under the trailer this spring and notice many holes cut in the coroplast. They all lined up with the cylinders, so am pretty sure it was done replacing the cylinders.

[speedster100]

Yup it happens when the unit has sat for while with the slides out. If you run them all the way in and out a couple times before pulling them in to travel it usually fixes the problem and they stay put.

[ChuckS]

Cycle the hydraulic slides a few times…this will bleed any air that’s in the system out.. if problem persists then it’s time to do a simple internal leak check on the slide cylinders.

I’d also check the Hydac valve for the slides (there’s only one for all) and make sure the manual override screw on the end of the valve is fully CCW.

If it isn’t it will allow fluid to bleed past the valve. Hydraulic pressure is what holds the slides closed as well as extended

[Cindy and Ray's Grand Tour]

Thanks all, we recycled the slides three times and it seems to have worked.

[packnrat]

for insurance use a slide pole.
they look like a expandable load lock for big rigs. can find them at home depot, about $25.usd each.
or buy a full sized one and cut shorter to fit.
sure does not cure the problem , but they work.

[skypilot]

Had the same thing happen - except we were lucky that it didn't happen while driving down the road. Ended up being a bad cylinder for the larger slide. Lippert has a test routine that they can provide you which has the procedure to test with. Also, if you have the hydraulic 'Level-Up' system, these might also raise (or lower) with that hydraulic problem. YouTube video by 'Getaway Couple' shows it happening.

[Rwalker]

I had the same problem coming back from Florida. Luckily, it happen on the last day. When I went to extend the slide-outs the first slide-out went part way out then stopped. I tried repeatedly, but could hear fluid rushing out somewhere. I then noticed the hydraulic tank was empty and some hyd. fluild leaking out bottom of trailer. Further investigation revealed the slide-out that came out 4 inches while traveling had the cylinder mounting nut fall off. When I went to extend the slide-outs, this cylinder extended and broke off the hydraulic hose fitting. I was able to get the hose repaired and remounted the cylinder back onto its bracket.