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Old 08-31-2020, 09:30 AM   #1
Scottsjeeprolet
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DeWald pump

So on my 3280RL the hydraulic pump isn't working good. Not producing enough pressure. I am in the Industrial pump service business and have had the pump apart. The pump itself is in good shape but the Hi pressure seals inside won't seal.

So i am thinking of getting this pump and making it work. I just can't justify spending $900 on a Lippert pump on a camper I am going to sell soon.

Has anyone else done this?

https://smile.amazon.com/dp/B07VGR42...ustomerReviews
 
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Old 08-31-2020, 03:46 PM   #2
larry-n-steph
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I have a 2003 2850 Montana and the hydraulic pump reservoir cracked and dumped all of the ATF. There wasn't a reservoir replacement so I was forced to get a new Lippert pump. I kept the trailer for my kids to use and I kept the old CMS pump which still worked great before leaking. I researched the pump you're thinking about and it just seemed like it was going to be too much of a hassle. I sure hope you can make it work for you.
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Old 08-31-2020, 04:05 PM   #3
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You are in the hydraulic pump business. You would know better than I what would work. I wonder about the flow rate for both pumps. For $230 I would try it. Let us know how it works out.
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Old 08-31-2020, 04:31 PM   #4
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Is the reservoir capacity great enough on the alternate?
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Old 08-31-2020, 06:52 PM   #5
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Originally Posted by Ram Montana High Country View Post
Is the reservoir capacity great enough on the alternate?
My company is not in the hydraulic pump biz. But I know how gear pumps work. The issue is sealing the hi pressure pipes inside the manifold. I ordered some new orings and copper hi pressure seals to give the repair one more try. If this doesn’t work I’ll get the pump listed above and figure out the wiring. The Dewald pump is bi directional and not operated by solenoids.
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Old 08-31-2020, 07:28 PM   #6
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Where are you getting parts for the Dewald pump? I tried a few years ago, no luck. Mine has an internal valve that leaks causing the slide to creep out. It also has a small leak where the tank joins the valve body, probably an o ring.
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Old 09-01-2020, 04:11 AM   #7
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Originally Posted by Hblick48 View Post
Where are you getting parts for the Dewald pump? I tried a few years ago, no luck. Mine has an internal valve that leaks causing the slide to creep out. It also has a small leak where the tank joins the valve body, probably an o ring.

I ordered these pressure seals on McMaster-Carr

https://www.mcmaster.com/93781A038/
And an Buna-N oring kit & Copper seal kit from Amazon. The Orings for the two tubes are a 012 size.
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Old 09-01-2020, 12:09 PM   #8
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Originally Posted by Scottsjeeprolet View Post
I ordered these pressure seals on McMaster-Carr

https://www.mcmaster.com/93781A038/
And an Buna-N oring kit & Copper seal kit from Amazon. The Orings for the two tubes are a 012 size.
Thanks! May have to tear into it after next trip (first one this year because of covid), leaving Sunday. Yea!
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Old 09-09-2020, 05:35 PM   #9
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I've got experience with this hit me up if needed.
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Old 09-09-2020, 05:35 PM   #10
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So after pulling the pump again and going over it I found nothing wrong with it. I have gauges on both ports and capped the fittings. When I tested it the pump went up to 2k psi on both sides. The fitting size is 1/4 JIC for the hose connection.
Now I am thinking it might be the kitchen slide bypassing too much fluid. It has a leak.
I learned the hard way not to leave the slides out. The piston rods corroded on two cylinders. I replaced one but am thinking I have to replace the kitchen one.
Cheaper than buying a new pump.
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Old 09-09-2020, 08:13 PM   #11
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The piston seals deteriorate in the cylinders. My kitchen cylinder also deteriorated and I was able to take the seals to a local company and get replacements so I could rebuild it. If the rod is badly pitted, it may need to be replaced. That cylinder on mine is short, but the rod is long as it was mounted midway under the trailer. I could not find a new replacement with the long rod, so I rebuilt mine. I had a contingency plan, to take the rod out of a longer cylinder and put it in my old cylinder. A last resort would be to have a new mounting tab welded to the framework closer to the main frame rail so the longer rod would not be necessary. I will have to edit my profile: 2002 Montana 2880RL
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Old 09-10-2020, 06:57 AM   #12
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My kitchen slide cylinder is the same length as the living room but with an extension welded onto the end of it.

Jetson, how did you get the end of the cylinder opened up? I removed the nut but cannot get it to unscrew.
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Old 09-10-2020, 08:06 AM   #13
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Quote:
Originally Posted by Scottsjeeprolet View Post
So on my 3280RL the hydraulic pump isn't working good. Not producing enough pressure. I am in the Industrial pump service business and have had the pump apart. The pump itself is in good shape but the Hi pressure seals inside won't seal.

So i am thinking of getting this pump and making it work. I just can't justify spending $900 on a Lippert pump on a camper I am going to sell soon.

Has anyone else done this?

https://smile.amazon.com/dp/B07VGR42...ustomerReviews
You would certainly be a guinea pig indicated by only one rating of a 4 on Amazon. Don't recall ever seeing that low a number of ratings.
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Old 09-10-2020, 08:14 AM   #14
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Originally Posted by jimcol View Post
You would certainly be a guinea pig indicated by only one rating of a 4 on Amazon. Don't recall ever seeing that low a number of ratings.

I did read the review and it was a person that used it for their slide and it seems to have worked. I cancelled the order for the power unit and going to replace the slide cylinder.
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Old 09-10-2020, 09:17 AM   #15
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My cylinders had collars with holes for a wrench to unscrew, but I did not have one big enough. I used 2 pipe wrenches, one to hold the cylinder and the other to unscrew the collar.
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Old 09-10-2020, 09:42 AM   #16
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FYI: you can use a double acting pump to replace the Dewald or Lippert, but the relief valve needs to be backed off to keep from damaging the lower pressure RV system. I have a KTI pump and I had to buy a new relief valve because it came with a tamper proof valve. I lowered the pressure then increased a quarter turn at a time until the slides come in OK. The KTI came with 1500 psi relief down, which I connected to the out lines and 3200 psi relief up, which I connected to the in lines. The relief valve whistles now when the slides come in. This is the pump I used. It is larger and heavier than the Dewald and Lippert:



https://www.amazon.com/KTI-Double-Ac...s%2C210&sr=8-1
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Old 09-10-2020, 09:51 AM   #17
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This is the cylinder I'm going to get after i verify the dimensions tonight when I get home. I know the kitchen slide has an extension welded onto the end of the rod and it's 3/4-10 thread and the old cylinder is 5/8-18.

So I think I'll need a 3/4 coupling nut and a piece of 3/4 all thread.


https://smile.amazon.com/gp/product/...KIKX0DER&psc=1
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Old 09-10-2020, 10:05 AM   #18
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I had a problem rebuilding the cylinder originally, the piston seal caught in the port for the hydraulic line and slid out of place. (that is why a replaced the Dewald pump. My original is fine.) I was not sure about the seal I was sold, PSM-218, because the base was narrower than what I took off. I found that if I inserted I small screwdriver into the port in the side of the cylinder I could get the seal down into the bore so that it works good now.


BUT, I have since found that the PSM-218WB piston seal has the same base that my cylinder had originally. If the base and top of your piston seals are the same width, this may be the seal you want.
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Old 09-10-2020, 02:53 PM   #19
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Good thing I checked. The kitchen cylinder is quite a bit shorter by 11”.
I had it out in under an hour. Got very dirty though.
I’ll keep you posted on what I find.
This is why you don’t leave your slides open all the time. If you do make sure to coat them with some sort of corrosion preventive.
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Old 09-10-2020, 02:59 PM   #20
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That cylinder has a 38" stroke. Your kitchen cylinder only has a 24" stroke, but an all-thread extension sounds like a good idea.
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