3701LK hydraulic cylinder problem

[Fyrmanjax]

Hello. This is my first post here. I thought I would see if I could find some information. We have a new to us 2020 Montana 3701LK. The couple we bought it from only used it for an office and for the kitchen. They towed it to their home and set it up under a cover put the slides out and didn’t move it for 4 years. It’s in really nice shape but after our first trip with it I have an issue. I was expecting something to happen. It looks like all 3 hydraulic slide out cylinders are leaking. One is leaking badly. The cylinders are all pitted so I am guessing that tore the seals. Does anybody know the size cylinder they use. They all appear to be the same size. I measured 46.5 inches from the front of the tube to the end of the cylinder with the slides out. It looks like taking them off would not be that difficult except keystone riveted the underbelly material on instead of screwing it. I’ve tried drilling and cutting the rivets and have hardly made a scratch. That is some super hard steel. Short of cutting the material I don’t know another way to get it off. Any other ideas out there? Thanks

[Carl n Susan]

There are numerous Posts here about the nails used and how to remove them. Her eis one of them.
https://www.montanaowners.com/forums...ad.php?t=76400

Remove the cylinders after you have access so you can measure them. You only need that if you plan to replace them from Lippert (at around $700 each). The better, i.e. less expensive, solution is to take them to a hydraulic repair shop and let them rebuild tham.

[Fyrmanjax]

Thanks for the advice. I’m gonna see if I can get the nails out. From there I can get the cylinders off and I’ll see if they can be rebuilt. The problem is they are very pitted and and has rust spots down the shaft.

[2 Yoopers]

Any descent hydraulic repair shop will have new shaft material in stock. They will remove the threaded on piston, then cut and thread a new shaft. New seals and packing and it will be good as new, and a lot cheaper.

[Fyrmanjax]

I’ll definitely take it to a shop and see what they say. I figured out how to get the nails out but they are a pain the butt. With all 3 cylinders needing repair that’s a lot of nails to take out to get the underbelly down. It’s gonna be job for sure.

[Kfinnert]

I agree with everything said here; my family, and many of my friends, are in the AG Business. I would look to a repair shop before buying new.

I have hydraulic cylinders on my RV. I replaced the pump, which was very easy project as long as I had the correct pump! I then found the parts I needed for the repair of hydraulic lines at our local tractor supply shop - I upgraded the PSI of my lines very cheaply!

If you find a good repair location, I like the AG businesses that I used, you'll have workers that know their stuff about the workings of the cylinders and are not just selling parts. AS such, you get a free education and reduced costs.

This was a fun project for me and a buddy, although timely to do it right - 2 days.

[twindman]

FYI I had slides creep out every 160-200 miles when new. Just happens that we were headed to the Goshen rally! Long story short, I ended up at Lippert and they just figure if one is bad do both of the big ones. So they put in 2 new ones without really testing anything much.
Now the good part for you (maybe). I guess since they knew where things were, they just cut holes in the coroplast. I forget exactly (haven't looked in a while), but I think the holes were only 18 inches square (plus/minus). After peeking thru the side after removing a few nails, maybe you could try this?????
Oh, also, this was in 2014 so the coroplast held together with whatever tape stuff they used.

[ChuckS]

If you look at the hydraulic cylinder rod ends on the slide and follow thru the frame hole you now have a center area of where to cut the coroplast covering to get access to both rod end nuts and hydraulic hose fittings

I had to lower my spare tire for access to area on my coroplast .. make a three sided cut leaving the front section intact ( prevents water intrusion )

Then you should have some reflectix insulation as shown in second pic , simply make three sided cut to now have full access to both slide lit rod end jam nuts and hydraulic hoses as shown in last pic.

My pic only shows one of the two cylinders due to angle I took pic at .. remove the hydraulic extend and retract hoses and put caps on them if you have them handy

Then remove frame attach rod end jam nuts and other rod end at slide bracket .. you can use the “ old cylinder “ as a rough setting for the rod end jam nit travel on the slide out bracket end

Attach new cylinder and hoses and then check hud reservoir level and cycle in and out a few times to purge air from system

Check the extended and retracted slide positions while doing initial bleed retraction and extension to verify if you need to make adjustments to rod end at slide out bracket

** Refer to Lippert hydraulic thru the frame manual for procedures to check adjustment and adjustment points


This is a very easy task if you have some basic mechanical skill sets.

I used Gorilla exterior black tape to reseal the three cuts in coroplast and it has been in place for 4 years now with no issues with tape sealing the cuts

[Mikendebbie]

For reference to help locate the hydraulic cylinder ends, here are a few screen shots from factory tour videos that show
(1) the reflectix layed on top of the coroplast,
(2) the clip angle for the hydraulic cylinder welded to frame and
(3) the hydraulic cylinder bolted in place.