Community Forums

johntaves · 06-09-2020, 11:32 AM

Does anyone know how the Dewald hyraulic slide/jack pump is built?

Mine crapped out while extending the jacks. The electric pump spins, but does not pump. The jacks were not yet to the ground, so there was very little pressure on the motor.

I was able to manually pump them back up.

It has clean looking fluid that is about 1" below the top of the big square tank. And besides, it crapped out suddenly, and now that it is back up, it still won't pump.

I don't see how I have a bad solenoid(s), because the pump spins as if there is no load, and it will not move the slide or the jacks in either direction. To manually pump, I rotate the solenoids to the "up" setting, and also turn this knurled knob that's on the hand pump portion. I am assuming that the knurled knob prevents my pumping from spinning the electric pump, and that the solenoids are either in the "up" or "down" position. All of this leads me to conclude there is nothing wrong with electrics or solenoids

I am in the Idaho wilderness, so I cannot take this apart and risk having no fluid holding up the jacks. I want to know what is broken so I can buy the right part.

The other headache is that gulfstream in their infinite wisdom made the front access door smaller than required to get at the unit. I had to unbolt the thing to be able to manually pump it. The hoses are making it very difficult to pull it out with hydraulics intact so that I can look at the motor portion.

The manual is here, but it does not have detail with respect to the motor.

Is there a key on the motor shaft?
Is the motor removable from the pump without spilling fluid?

I am totally failing to find replacement parts for this. The manual has the part number for the motor/pump assembly (OK21500S), but google gives me nothing that looks close, except for a used part from visionerv.com. I am all in favor of a used part, but would like to know what failed.

My understanding is that Dewald was bought and bought again and lippert might be the owner now.

Another thread leads me to believe that my motor might be like
this. This does not have a shaft with a key.

The part manual seems to indicate that the pump is not sold separately from the motor. I find that it is not sold at all. When these go bad, is there some tank, solenoid, pump, motor all-in-one replacement?

Do these slides and jacks wear out over time such that it is probably better to do a whole system swap? My jacks do pop sometimes dropping a bit each time, so the system doesn't hold fluid perfectly. They also drop over the course of a few weeks when in the retracted position. Is that normal for a good unit, or am I seeing age in the jacks and solenoids?

johntaves · 06-11-2020, 11:58 AM

Lippert did eventually end up with Dewald, but does not have a replacement part for that pump. They suggested I call Custom Cylinders to see if they will repair it. The man that answered was a huge help. He will repair the pump, but he says that there is no way to estimate how he'll do it. He might have to make something to fit a different pump.

I also learned from him:

The jacks will not drop when the hoses are removed. There is sufficient friction to keep them up. However, if I drive, they will wiggle down, (and dribble a corresponding amount of fluid out of the hose). He says it will not take much to keep those jack up, however, I will plug the hoses if I have to drive with them disconnected.

The pump is in the reservoir. There are 2 thin aluminum things sandwiched between the motor and the reservoir, one is the manual pump, and the other is just a fitting that has a bearing to run the shaft through to the pump.

I am still searching junk yards for a replacement.

johntaves · 06-16-2020, 05:21 PM

I found enough similar looking pumps for sale and determined this is a Parker Oildyne series 108 pump.

The customer support was good and I determined that they will sell p/n 775616 pump replacement kit. This is the inner pump.

Because mine was older with different pickup tubes, I have to get:
two elbows, p/n 775914, two extensions p/n 366762, and two filters, p/n 410521.

johntaves · 08-20-2020, 10:44 PM

I received a message from some user that wanted to know where I got the parts. I called Parker Oildyne in MN. They hooked me up with support via email and someone told me the part numbers I needed. I then had to contact one of their distributors to order the part. They do have a website where they can be ordered, but one of the parts I needed was not on the website, so the dealer had to do it for me.

johntaves · 03-04-2021, 07:41 AM

I got the thing working with the new pump internals.

However, I was not very satisfied that I had determined the failure. My pump internals seem fine. It failed suddenly, so I expect to find something broken, but nothing is broken. I don't see why a worn pump would fail without spilling fluid and without leaving some trace.

Several months later, it failed again. This time it would struggle to retract. It would extend easily, but as soon as I reversed, it struggled. The motor consumes the amps, gets hot and shuts off. After it cools a bit, it resumes and the cycle continues. I managed to get the jacks up enough to drive and disconnected the panel to stop the alarm since they were not up enough to trigger the up sensor.

I had no good theory except that somehow the motor failed in the one direction. They are relatively cheap so I ordered another. Then I remembered that I have the old one, so I put it in. It spun in both directions without doing anything just like it failed months ago. This made it clear that there was nothing wrong with the pump.

I remeasured the coupling that is between the motor and the pump (see image) and concluded that my previous measurements were wrong. I then spun the motor in both directions for a good amount of time, took it apart again and the coupling was clearly showing wear where the pump tab was not in the groove.

I found someone to machine me a new coupling and all is good now. My thinking is that the cheap pumps are probably a knock off and do not have the same distance to the end of the shaft, and my original pump just wore down its bearing. I assume that my extend-only-no-retract failure was the coupling jamming in one direction and not the other. I don't think the original coupling wore down, so I did not want to buy a new one. I did not hear back from Oildyne when I asked if there are different sizes for these.

One machine shop wanted $275 to make it, which is reasonable, but also ridiculous. I called a fabricator. He had a young employee going to school that could machine one for me. I gave him $40 for it.

Contact me if you have a need for a coupling.

cduperon · 05-02-2021, 06:38 PM

Mine was working both way and now only extends. I run to retract and the motor/pump makes a grinding/chatter noise. I am wondering if this coupler could be my issue. The motor works both directions and I can manually pump it closed.

Wondering if you have another one of these available, I would like to have on hand before I tear it all apart.

johntaves · 05-03-2021, 06:07 AM

Quote:

Originally Posted by johntaves

I assume that my extend-only-no-retract failure was the coupling jamming in one direction and not the other. I don't think the original coupling wore down

I changed my mind about the above. I think the motor's bearings wear down and that increases the distance that the coupler has to span.

I think the second motor trashed a brush or something. I don't think the coupler can bind.

I bought a third motor, and it stunk from the get-go. I returned it. It was clearly used. With 2 replacement motors stinking it up, I am not confident about these. I assume they are knock offs, but I have no idea how to find the original spec version. They are like $70, so cheap enough not to worry about buying and hoping it stays OK.

Quote:

Originally Posted by cduperon

Mine was working both way and now only extends. I run to retract and the motor/pump makes a grinding/chatter noise. I am wondering if this coupler could be my issue. The motor works both directions and I can manually pump it closed.

Wondering if you have another one of these available, I would like to have on hand before I tear it all apart.

I do have 2 couplers, but they are different and custom made. You have to take it apart to measure and determine if that's the problem. It seems like maybe you are spinning in one direction and barely holding on in the other. Most likely you should just get a new motor.

It is not difficult to get it apart. You need a ratchet 3/8" end wrench to get the 2 bolts that connect the motor to the pump. In my situation, it is complicated because the pump assembly is half hidden behind the front of the RV. You cannot manually pump without unbolting it from its mount and shoving it aside a bit. I had to feel around with my hands to figure out where all the bolts and nuts were.

I have 2 bolts holding the motor, pump, and tank assembly to the base. 2 3/8" bolts holding the motor to the pump, and 3 nuts holding the 3 wires. That's all I have to do to get the motor out.

You should take yours apart and prove that the motor spins OK in both directions. Put a drill on the pump and see if you hear anything bad in both directions. Measure the distances to prove your coupler is too short.

If it is too short, I would just get a new motor.

cduperon · 05-03-2021, 08:22 AM

I am going to run it as is for this trip and just manually pump it closed, then tear it apart when I get back home.

The way my luck goes, something will break pulling it apart to test/fix, better off waiting.