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Old 04-13-2021, 08:01 PM   #1
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2004 Vintage HWH 325 Jack System Will Not Run

I picked my RV from storage after 7 months. I first sprayed the jacks with WD-40 and they retracted fine. However, when I got to my next desination the jacks would not go down, but my slideouts work normally.

When I try to manually put the jacks down or select the auto-level option, my jack motor just "freewheels" (meaning I can hear it) and nothing happens.

With the motor running I can't see any leaking hydraulic fluid either, but I suppose I need to take another look when the weather is better.

I have not checked the level of my fluid in my hydraulic reservoir, but I will do that tomorrow when the sun is shinning. Or the next day, because it's raining where I am at.

* I would think if my slideouts work fine, that my fluid level is not an issue, but I'm just a novice when it comes to HWH systems.

I reviewed the HWH manual and troubleshooting sections and it suggests I may have a bad shuttle valve. TBD.

Does anyone have another opinion, and do you know a procedure that makes it possible to free-up the shuttle valve if debris gets in it?

Note: Last summer I replaced my hydraulic fluid with std. Dexron III (no additives). I used a 12V pump to suck the hydraulic fluid out and I think I was careful not to let any debris in, but maybe I was not careful enough?

I don't believe this is a factor. But what causes a shuttle valve to go bad, except for crud clogging it up?

Note: The diagram below is a HWH 625 system, but I think it operates on the same principles as my HWH 325 system with different solenoid valves. Is that right?

Also, I don't know if my 325 System has a 50PSI switch or if I do have a 50 PSI switch, but my LED monitor/status lights are slightly different or non-existent. (This is a side comment which probably has nothing to do with the shuttle valve, but it may have something to do with diagnosing my problem. TBD.)


* What do you think my jack problem is if the motor runs but nothing happens?

* Why can't I get the jacks to go down when my slideouts work?

* Can you cleanout a shuttle valve?
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Old 04-13-2021, 08:31 PM   #2
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Here is what the HWH manual says, but possibly there is another reason my Jacks just decided not to work. And there were no symptoms leading up to this point. Just "boom" ...nothing happens when I press the jacks down button or if I press the Auto Level Button.

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Old 04-14-2021, 05:00 AM   #3
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I cannot be of specific help, but I wonder what kind of filtration is in our HWH systems?

If I had a valve that was intermittent or behaving badly, that might be the first place I would go investigating.
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Old 04-14-2021, 05:56 AM   #4
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OK, I can supply some useful information. In general, shuttle valves can be cleaned out. My hydraulics experience, is general and is not specific to HWH.

It is fairly simple. Usually a hot clean in an ultrasonic cleaner with a degreaser. Also, the o-rings can be replaced. Your local hydraulic supply shop can easily help you get the right o-rings. If you have gone this far, new o-rings are in order. Less than a dollar each, more likely 25 or 35 cents.

At home, not having exotic degreasers, I find I can usually use water and laundry detergent. I use laundry detergent because it is next to the area where I operate the ultrasonic cleaner. Others use Simple Green, Dawn, and other stuff. I would exercise caution with solvents, due to flammability. Soaking the valve in the hot tank is your friend.

Shuttle valves can wear out, but normally it is doing things with greater frequency than leveling jacks.

Also, FWIW, I use PB Blaster on the pistons, as it is mostly ATF fluid (and detergents, etc.) and is a little more compatible with the ATF used in the HWH system. WD-40 is a bit different (fish oil and detergents and special sauces), and both are commonly found. So I just use PB Blaster.

When I do, I juice up the seal area, then mop it clean. Then juice it up again, and use a soft rag after it starts draining down the piston. You want a thin layer left behind, but you want the piston and seal to be clean.

Look at the bright side, having a problem extending the jacks beats having a problem getting them retracted. (grin)
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Old 04-14-2021, 07:38 AM   #5
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You make a good point! ...I mean points!

This shuttle valve gets relatively very little use so what is the problem?

A) Some debris got stuck in in the shuttle valve, preventing it from opening the port the hydraulic fluid uses to travel up to the jack manifold, if that is possible?


B) Those O-rings just need to be replaced?


C) Maybe I have a leaking jack solenoid seal or that there is a 5/8" cap that is leaking? ...I have read these things need to be tightened up ever 10 years? (Mine is 17 years old now.) ...And I do see some hydraulic fluid leaking on the left side of the manifold (not the right side above the reservoir). However, I think these 5/8" caps are on the right sides, so I don't know where the leak is coming from at this point. Moreover, I would think my jacks would just run slow if there was a very slow leak.

I see that most owners just replace the shuttle valve, and then they often claim success, but no one has discussed how to clean the shuttle valve or if just replacing those O-rings solves the problem or problems. (Seems easy enough.)

Why can't we just remove the o-rings and then soak the valve in a "parts dip" like we use to do when overhauling a carburetor? ...and then just re-install with new o-rings?

==> Something is preventing hydraulic fluid from getting to the jack manifold and that tells me it's the shuttle valve that is the main problem, and the hydraulic leak I see is a second problem.

I will be doing some more diagnosing today and I'm hopeful AZ-Pete will set us all straight too. This condition sounds like it should be text book stuff, but then again I don't read or speak "hydraulics" very well.
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Old 04-14-2021, 08:08 AM   #6
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I only learned enough about hydraulics to "get the gear down."

Sidebar: A fellow ham radio and aviation guy, Dick, was the flight engineer on the Fuddy Duddy, a B-17 in WWII. On one mission they got shot up pretty bad, and he could not get the gear down. That was of particular concern to the belly gunner who would likely perish in a gear up landing. After all fluids on board were set aside for placement into the hydraulics reservoir, Dick passed a coffee can around to all the crew, for one final donation. The gear came down, and the plane was down for maintenance for the rest of the month.
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Old 04-14-2021, 08:15 AM   #7
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It seems that the shuttle valve is in serial for the lift system, so it's failure would cause the failure of the lift portion of the system. Can you readily pull the shuttle valve and perform a visual inspection?

Not shuttling might explain your observation of the lift system "free wheeling" or unloaded hydraulic pump.
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Old 04-14-2021, 08:25 AM   #8
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Great story. Sometimes I feel like a "belly gunner" myself under this rig. So the moral of the story is to never throw anything way, like that coffee can.
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Old 04-14-2021, 08:42 AM   #9
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My mother was of that generation. Kept Life Magazine cover pages but let wills and death certificates get dumped after a house sale.

Go just in time, (literally) and fill the beer bottle as needed.

Does it appear that you can don some gloves and easily pull that shuttle valve? It's a great project for a Wednesday late morning...
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Old 04-16-2021, 11:21 PM   #10
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I talked to HWH and they said the shuttle valve can wear out and debris in the reservoir will not clog it under normal considerations.

Still if, you can take the shuttle valve apart I doubt wear is the problem. More likely it gets stuck in a position and cannot free itself... which can renter one or the other symptoms:

A) Your jacks will not go down, but your slideouts will work; or...

B) Your slideouts will not work, but your jacks will go down.

I ordered a new shuttle valve, but if I have time I will try cleaning my old shuttle valve in parts dip and will replace the o-rings. And then I will replace it to see if both my jacks will extend and my slide outs will operate normally. If not then I will put the new shuttle valve in and test the system.

So standby and I will let you know the results in another week or two.
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Old 04-16-2021, 11:34 PM   #11
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Where did you get the annotated diagrams on the hydraulics?
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Old 04-16-2021, 11:35 PM   #12
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Where did you get the annotated diagrams for the hydraulic system? They look very helpful.
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Old 04-18-2021, 07:02 PM   #13
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I had the same problem, I replaced 50PSI switch, problem solved. When I put the new switch in, I later looked at the old one and I think it was a corroded connection.
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Old 04-18-2021, 08:05 PM   #14
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Sorry Imprsd,
I wish I'd gotten to this thread a lot sooner. IT'S YOUR SHUTTLE VALVE, for sure! I had the same EXACT problem back a few months ago with our '04 Itasca Horizon 36GD with the CAT C-7 330HP and, the 625 Computer Controlled Automatic Leveling System. Yes, when you push the extend arrow for ANY section(s) jacks, and the pump just spins, about 99.9999999999999% of the time, it's the shuttle valve.

The and, for the most part, the shuttle valve does NOT PLAY A PART IN THE USE OF THE SLIDES. It's only in effect, when using or, attempting to use the jacks. The way that shuttle valve is designed, it needs 800 psi to overcome the internal spring pressure that keeps it in default CLOSED position. Once that 800 psi is achieved, the hydraulic oil can now be pumped from the reservoir, through the shuttle valve and, into the appropriate solenoid that is being asked to work in lifting a particular jack or set of jacks.

That shuttle valve is assembled with a very, very tiny 3/16 stainless steel nut, that has an internal thread of less than 1/16" inch. And about 90% of the time when the shuttle valve is determined to be the culprit in a failed jack operation, it's because THAT TINY NUT HAS LOOSEND AND FALLEN OFF.

When that happens, the internals of that shuttle valve now become dislodged and the valving won't do it's job. There are HWH systems running all over this country, with a very small, 3/16" nut, laying on the bottom of the reservoir. There is a screen pickup for the intake of the pump so, no need to worry about that nut getting into the pump gears.

In my opinion, no need to mess with that one you have. Just get a new one from Paul Maddox, aka AZ PETE here and, on other RV forums. He's the one and only HWH outside Rep. He's a great help with many folks who've had HWH issues. He's helped me more than a couple times. Once you get that new shuttle valve, your system will work like a champ.
P.S. Some folks have more than one on hand since, that part of the HWH system can be rendered useless if it fails. The shuttle valve doesn't play a part in the retracting of the jacks. It's default position allows for the fluid to return from the jacks, back into the reservoir. It only steps into action when the jacks are needed.
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Old 04-20-2021, 10:02 AM   #15
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FireUp: Thanks for the tips.

I ordered a Shuttle Valve and will be installing in when I get to Rocky Point. So I will confirm this is the fix soon enough.

I also have a wet area under some of my jack solenoids... on the front side of the pump. (See Picture.) ...But I can't tell where it's leak is coming from? I suspect one of my jack solenoid seals is not sealing 100%, but IDK.

It is wet in that area, but I also see where water coming off my dash AC evaporator... which drops down on top of my generator... which blows off and runs down a loom of wires... to the HWH pump.

However, I can't ignore the stain on the last jack solenoid (I think actuates the LR Jack). What do you think about this discoloration? (See picture.)

How do you unscrew and tighten a jack solenoid? ...And is the procedure the same for the slideout solenoids too?

=== Shuttle Valve Operation ===

FireUp says: The shuttle valve's default position allows for the fluid to return from the jacks, back into the reservoir. ...And it only steps into action when the jacks are needed.

And when I look at my 625 Jacking System Diagram (above) I also see there is a 3,500 PSI pressure relief switch.

So I'm guessing the shuttle valve opens at 800PSI and then shuttles hydraulic fluid to the manifold, where the Jack Solenoid/Switch activates the jacks.

And that 3,500PSI switch on the other end of the "U-Tube" is N.C. ...but opens when you push the Retract Jacks button... releasing the pressure in the system... and then those heavy duty jack springs pull the jack back into a stowed position. Is this how this system works?

I'm not sure. And anyone confirm this analysis and/or make corrections to my assumptions?
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Old 04-22-2021, 05:50 PM   #16
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It was the shuttle valve

So I ordered a new Shuttle Valve from HWH (Part #RAP7964) for $89 and that fixed my problem. Here are my repair notes:

114,000 miles.

If you have good access to the shuttle valve on top of the HWH System, this is about a 1.5hr job, for us first-timers, and almost anyone can do it. Plus you do not special tools. Just a...

* Screwdriver + 7/16” wrench
* 9/16” wrench
* 7/8 deep socket and long 3/8” drive extension and ratchet
* 1-zip tie
* Mineral spirits, paper towels, rag.

* Do not proceed to replace the shuttle valve until you verify you have fluid in the reservoir and all those 5/8” caps are tight. (Finger tight and then a little more.)

* Open the top lid to your entry step to gain access and prop up so you can work underneath.
* The shuttle valve is visible where the U-tube pipe connects to it closest to the door.
 CLEAN off everything real good using mineral spirits on paper towels first then do it again using a rag.
 Remove the U-tube from both ends (evenly). Then sand off the rust and paint if required. Notice: the Bend in my tube is up, but it probably does not matter. It’s just a tube.
 Use a zip tie to pull back the battery cable that runs over the top of the U-tube pipe.
 Use a large crescent wrench and spin off the 90-degree-elbow screwed into the old shuttle valve. (Do not remove the 5/8 cap next to it.
 Check all four 5/8”caps are finger tight… plus little more torque. Do not over tighten.

Note: One of my caps required 2 full turns!

 If you see a leak coming from under one of those four 5/8” caps, then this is a good time to replace them. You can get these o-rings at any auto parts store or hydraulic shop and I think they are Standard #604 type o-rings. …The HWH o-ring Part #: 03-905-9N and they are only $0.25 each.

 Use a 7/8 socket with long extension (3/8” drive) and unscrew the shuttle valve. Note: I’s on tight!

 After you unscrew the shuttle valve you will need to pull on it by hand to break the o-ring seal. Then lift off and remove.

 Unscrew the 90-degree-elbow off the new shuttle valve by hand -- and install the new shuttle valve in to the top of the Jack Manifold.

Note: You will need to push down on the shuttle valve real hard to start the first threads; and I even had to tap on the top of the valve to get the o-ring to seat. (I used my ratchet.)

…Then you can use your 7/8 socket to tighten the shuttle valve DOWN REAL TIGHT!

 Screw the new 90-degree-pipe-elbow into the new shuttle valve; and when you get it “snug” you add one more full turn.

Note: This is where your use a 7/16” wrench (positioned vertical) and then you put the screwdriver thru the closed end part of the wrench… to make a “T-Handled-Wrench you turn like you are working on a lawn sprinkler. (See pictures.)

 Reattach the U-tube and make mirco-adjustments so the U-Tube fixes evenly over both pipe threads. Note: I found it’s best to first screw the U-Tube to the new shuttle valve and then start threading the other side. You also can use blue-Loctite on the other (older) thread.

Note: So you can see what is inside a Shuttle Valve I took a few pictures; and I think if shake it... and you hear it raddle... then you know you have a bad shuttle valve. IDK... All I can see is a nylon part the slips over the plunger and maybe it wears to the point it cannot hold back pressure.

Does anyone know how these shuttle valves fail?

…And you are done! Easy-peasy!

Now start your engine to get a good 12V to the pump, and attempt to put our jacks down as you normally would. Note: You might find them unresponsive at first, so try the other side. This is because you new shuttle valve has not hydraulic fluid in it. So be patient and don’t over work your jack motor. I.e., let it rest every 10 seconds. …I had to try 3 time before the jacks would go down.


* Add an extra ground wire from our pump motor 5" bolt to your step metal lip. This will help your pump get a better ground and these pumps have been known for weak grounds. So this is an easy upgrade other forum member told me about.

* I had a lot of grim from when the previous owner over filled the tank. So I used a biodegradable WD-Degreaser and/or a $1 jug of “BBQ/Oven” cleaner you can get at the Dollar Store, and this stuff does a great job degreasing and it’s not mineral based. Then just use a high pressure water hose to remove the grime! (WORKS GREAT!) And then I sprayed just a little WD on those Jack solenoid wire ends to keep them from rusting.

PS That WD-Degreaser product is fantastic and it’s new. The only place you can get it is through Amazon, but this will change as more people discover it. I also use it to clean my Harley and it does a fantastic job cleaning chrome and calcium in your shower… without that WD smell! You really should try it.

==> See attached .pdf if you want to print this procedure out.
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File Type: pdf HWH SHUTTLE VALVE R&R – 2004 ITASCA HORIZON 40AD (PDF).pdf (834.4 KB, 5 views)
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