Hello,
Can anyone tell me if the later model HiLos came with a hydraulic overflow tank as opposed to just a fill/breather cap like my 1989 has??

Since we have owned our HiLo (bought it used) it has always blown the fluid out of the fill/breather cap when lowering the top section in one continuous motion/lowering. It doesn't blow fluid out if I lower it in increments.

I believe HiLo engineers built them to be lowered in one continuous downward motion...like on their product video. But maybe they didn't test these systems enough to find out that they will spew fluid out of the fill hole!!??

If you're wondering...No, I have not overfilled it; It is at 1 inch below the fill hole measured with the top down.

I will be modifying the Hydraulic system today with a DIY overflow catch can/tank.
Any info is greatly appreciated.

Angel, my 2007 Towlite has just the reservoir, with the single fill cap. There's no overflow tank. I wonder if your trailer's return tube is possibly not positioned properly in the tank? I have no idea how it SHOULD be positioned, perhaps with the end as far away as possible from the filler hole? Mine has blown a bit of fluid out of the tank, but I always thought it was because I overfilled it.

Your idea of a catch can is a good one, but it will have to somehow return the displaced fluid back into the reservoir, or it might as well have been pumped to the ground. I wonder if applying a reducer to the end of the overflow tube might slow down the rush of fluid returning to the tank? It would slow down the lowering, but that would not be a problem.

- Jack

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Hi-Lo 1707T - Tire Minder TPMS on Tow Vehicle and Trailer, 300W Solar Battery Charger, Equal-i-zer WDH, Progressive Dynamics Converter, Fan-Tastic Fan, LiFePO4 battery 12V DC Electrical System, SoftStartRV mounted on A/C
2024 F150 Platinum FX4 3.5L PowerBoost SCrew

Hello everyone,
As I mentioned on this post, I was a little frustrated with my hydraulic system blowing some fluid out of the fill/vent cap every time I lowered the top in one non-stop express to the bottom operation (haha). I do believe that's how the system was designed to work, without spewing fluid all over the place. So to remedy this problem I made a DIY overflow/catch container. I replaced the plastic fill cap with a brass fitting and attached a hose to it, I then used a jar and drilled a hole on the cap and fit the hose thru it. I also drilled a small vent hole on the cap to allow air pressure to escape. I placed the hose about a 1/4 inch from the bottom of jar. Now when I lower the top in one continuous motion/operation the fluid that exhausts/blows out goes into the catch jar.
And get this; when I raise the top, whatever fluid that was is in the jar gets sucked back into the hydraulic system!! Pretty much the same way an automobile's coolant overflow tank works; excess amount is caught by tank until it needs it, then sucked back in when needed. I am no longer losing fluid all over the battery compartment or on the ground when I lower the top in a continuous operation. And I don't have to lower the top in increments!! Seems to be working really well, I Like it!! Let me know what you think of my DIY project, thanks.

Attached Images

HiLo Hydraulics.jpg (309.3 KB, 9 views)

I like your solution to the problem. You should get a patent for this!!.

Oh well DUH! Of course you've designed a system that takes care of the stupid post where I was concerned about the fluid not returning to the reservoir! Sometimes I amaze myself with my stupidity. That's a beautiful fix, Angel - good on you! Now your lift system always has MORE than enough fluid and the excess, if there is any, is not a problem.

- Jack

Jack don't beat yourself up. I would never call you stupid. Time and time again you have shared your engineering expertise on this forum. It has been appreciated.

Thank you sam - but I find it laughable that I didn't realize the simplicity and beauty of Angel's idea when he posted it. I just wasn't thinking of a "closed" reservoir that would have to pull the fluid out of the overflow bottle as the system was pressurized.

- Jack

We no longer have our HiLo, but never had an issue in the 20 years we had her…there was never a need to add fluid either. Good luck!

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Elaine and Bill Stevenson
Former HiLo-Classic 310S
2011 Toyota Sequoia