Dump Cable Lubrication

[howson]

11 Mar Update: This idea shown in this post did not help long-term. I have abandoned the idea. I've left the thread so others who may be considering trying it can benefit from my experience. -Howard

What you'll see in my video below is not a time-tested process. What you're going to see is my first attempt using the Motion Pro tool I bought.



I haven't seen anyone else use this tool for this purpose, so hopefully this is an original post. (I usually "steal" the ideas of others--but try to credit them when I can remember who they are.)

The video below ends abruptly (I fired the videographer) so just trust me that the cables work much better. (There's a storm rolling through NW Florida now so any further videoing will have to wait.)

What I learned during the process of using the Motion Pro tool is that it works on the dump cables, but not instantaneously. Holding the tool in place under pressure to allow the lubricant to work it's magic is a key step. I suspect that if I repeat the process more lubricant will make it down the cable making it easier to use.

Let me repeat for emphasis: this is not a time-tested process. There may be unintended consequences I haven't thought of (or experienced). I'll update this thread as appropriate.

For those that have followed Cate&Rob 's plumbing threads you'll know that he incorporated "bomber doors" into his coroplast so he can access his dump valves and cables for cleaning and lubrication. He's often commented that some difficulties with cable operation is due to routing. That can only be fixed by dropping the coroplast and taking some of the bend out of their original installation location.

My dump valves worked OK right from the beginning (I've owned the camper about 1.5 years) so the current difficulty is not due to the initial installation. It's corrosion in the cable. There could be some problem at the valve itself, too. I also tried the canola oil trick I first saw on Youtube, so we'll see if it helps, too: https://www.youtube.com/watch?v=BFS0ry19tTU

[JCR GD]

JFWIW... This stuff did wonders for my dump valve cables


Got it from Amazon.

[Cate&Rob]

Hi Howard,

It will be interesting to learn if this works over time. The construction of a dump valve pull cable is significantly different than a brake apply or throttle cable. The inner wire in the dump valve cable is a very loose fit in the cable sheath (except for the first few inches of solid rod at the handle end. Unlike a brake or throttle cable where there is usually a fairly tight clearance between the inner cable and the outer sheath for its entire length. To fill the space between the cable and sheath of a dump valve cable is going to take a lot more (and maybe thicker?) lubricant than the other types of cables.

My experience is that the binding in the dump valve system is at one end or the other. Either within a few inches of the handle or within the gate valve itself. The other major cause (if a gate valve cable is difficult to operate from new) is cable routing. When I replaced all my gate valves and cables, I discovered that the factory cable routing did not meet the routing recommendations that came with the new valves.

As some may recall, I cut apart one of my removed gate valves to figure out why they were so difficult to operate (see attached.) The gate valve plate pulls past a pair of seals into a closed space. If these seals leak at all (very probable) then whatever is in the tank ends up in the space that the gate is supposed to retract into. The other major point of binding is where the pull rod for the plate comes through a rubber seal. There is no way to get lubrication to this seal. Either down the cable or by putting lubrication into the tank. This led me to put zerk grease fittings on each of my gate valves. This keeps the gate space and pull rod seal lubricated. This works well . . . but does require access to the gate valves which are inside the coroplast in most cases. I installed opening doors so that I could get to mine.

Rob

[howson]

Hi Howard,

It will be interesting to learn if this works over time. The construction of a dump valve pull cable is significantly different than a brake apply or throttle cable. The inner wire in the dump valve cable is a very loose fit in the cable sheath (except for the first few inches of solid rod at the handle end. Unlike a brake or throttle cable where there is usually a fairly tight clearance between the inner cable and the outer sheath for its entire length. To fill the space between the cable and sheath of a dump valve cable is going to take a lot more (and maybe thicker?) lubricant than the other types of cables.

My experience is that the binding in the dump valve system is at one end or the other. Either within a few inches of the handle or within the gate valve itself. The other major cause (if a gate valve cable is difficult to operate from new) is cable routing. When I replaced all my gate valves and cables, I discovered that the factory cable routing did not meet the routing recommendations that came with the new valves.

As some may recall, I cut apart one of my removed gate valves to figure out why they were so difficult to operate (see attached.) The gate valve plate pulls past a pair of seals into a closed space. If these seals leak at all (very probable) then whatever is in the tank ends up in the space that the gate is supposed to retract into. The other major point of binding is where the pull rod for the plate comes through a rubber seal. There is no way to get lubrication to this seal. Either down the cable or by putting lubrication into the tank. This led me to put zerk grease fittings on each of my gate valves. This keeps the gate space and pull rod seal lubricated. This works well . . . but does require access to the gate valves which are inside the coroplast in most cases. I installed opening doors so that I could get to mine.

Rob

I knew most of that story, but your post has filled in the gaps.

Seems like there are two issues. The corrosion that is binding the cable itself and the internal binding in the valve.

I don't expect the Motion Pro to solve the internal valve binding issue, but I am hopeful it will solve the cable binding due to corrosion, even if the cable is different from a brake or throttle cable. There's no doubt of the corrosion--it was very evident.

The canola oil for the internal valve issue seems goofy, but it's not going to hurt anything to give it a try so I dumped some down into the kitchen and bathroom gray as well as the black tank. If it doesn't work for the internal valve binding, I think what I'll try is similar to what you've documented but instead of a zerk I'll try using a long, flexible, aerosol can "straw". I'll superglue it into place and extend the lower part through a small hole in the coroplast. I'll find a cap, of course, to keep foreign debris from inadvertently entering. Once in place it should be easy to connect the lubricant of choice in an aerosol can to spray into the dump valve housing.

[boyscout]

What you'll see in my video below is not a time-tested process. What you're going to see is my first attempt using the Motion Pro tool I bought.

Howard, thanks for this and other videos. You keep apologizing for them while you're making them but they're great. I'm thinking of giving up HBO!

[Canyonlight]

Howard, thanks for this and other videos. You keep apologizing for them while you're making them but they're great. I'm thinking of giving up HBO!

X2 - I may even give up my sports channels !!!

Dan

[Cate&Rob]

The canola oil for the internal valve issue seems goofy, but it's not going to hurt anything to give it a try so I dumped some down into the kitchen and bathroom gray as well as the black tank. If it doesn't work for the internal valve binding, I think what I'll try is similar to what you've documented but instead of a zerk I'll try using a long, flexible, aerosol can "straw". I'll superglue it into place and extend the lower part through a small hole in the coroplast. I'll find a cap, of course, to keep foreign debris from inadvertently entering. Once in place it should be easy to connect the lubricant of choice in an aerosol can to spray into the dump valve housing.

Hi Howard,

Remember that with the "canola oil" treatment . . . the oil will float on top of the tank contents . . . it will only reach the gate valve seals for a brief moment while draining a full tank.
Rather than a remote aerosol straw . . . why not a remote zerk grease fitting? A threaded fitting into the gate valve (as I did) could transition to a length of 1/8" copper/plastic tubing with a zerk accessible under the coroplast. This was actually my first plan . . . before I came up with the "bomb bay door" plan .

To echo the recent comments . . . I also really like your videos . . . I am going to have to figure out how to do this . . . I am stuck in the Powerpoint/pdf generation!

Rob

[Cate&Rob]

The "bomb bay doors" plumbing access . . .

Many following this thread will know about where the "bomb bay" reference comes from . . . others will not.
Attached is the summary of my entire plumbing system rebuild . . . a few years ago.
Buried in this is my alternative for "gate valve access".

Rob

[howson]

. . . why not a remote zerk grease fitting?

Because I didn't know there was any such thing! You gotta remember you're conversing with a former Avionics technician.

Thanks, everyone, for the kind comments.

[JBill9694]

With the zerk fitting on the on gate valve housing (bonnet), what are you doing to minimize your pressure when lubricating? Slow stroke on your grease gun or are you using a pressure gauge? How often have you found it necessary to refill the bonnet?

[Cate&Rob]

With the zerk fitting on the on gate valve housing (bonnet), what are you doing to minimize your pressure when lubricating? Slow stroke on your grease gun or are you using a pressure gauge? How often have you found it necessary to refill the bonnet?

I am not filling the gate valve housing (bonnet). Just a couple of pumps of a small grease gun once a year. I cycle the gate back and forth as I do this and can usually see a film of grease on the pull rod and feel the gate motion getting easier and smoother. The replacement Valtera valves and cables make the connection between the cable and the gate pull rod with a set screw . . . so it is easy to disconnect this to isolate resistance in the motion of the gate from binding in the cable. The OE cable (at least mine) made this connection with a hook end of the cable which could not be easily disconnected.

If I over greased this setup, I expect that pulling the gate back into the cavity would push any extra grease out past the gate seals to the interior of the dump pipe. These seals run on the flat plate surfaces of the gate and are not likely to retain much pressure from either side.

Rob

[JBill9694]

Thanks for the detailed response. Sounds like you have things well in hand.

[bertschb]

Howard-

I really appreciate your posts and videos too. Keep 'em coming! One thing I learned with my last 5th wheel was to cover the dump valve handles when connecting and especially disconnecting water hoses to the Nautilus water panel. This prevents water from dripping down onto and into the gate valve cables. This happened to my 373FB-R and the cables/housing started rusting and binding within a couple days. That won't help for gate valves that are under the RV and exposed to road grime but I think it will help for the valves in the water panel. I'll find out when our new 5th wheel arrives.

[Jerry Kuiken]

11 Mar Update: This idea shown in this post did not help long-term. I have abandoned the idea. I've left the thread so others who may be considering trying it can benefit from my experience. -Howard

What you'll see in my video below is not a time-tested process. What you're going to see is my first attempt using the Motion Pro tool I bought.



I haven't seen anyone else use this tool for this purpose, so hopefully this is an original post. (I usually "steal" the ideas of others--but try to credit them when I can remember who they are.)

The video below ends abruptly (I fired the videographer) so just trust me that the cables work much better. (There's a storm rolling through NW Florida now so any further videoing will have to wait.)

What I learned during the process of using the Motion Pro tool is that it works on the dump cables, but not instantaneously. Holding the tool in place under pressure to allow the lubricant to work it's magic is a key step. I suspect that if I repeat the process more lubricant will make it down the cable making it easier to use.

Let me repeat for emphasis: this is not a time-tested process. There may be unintended consequences I haven't thought of (or experienced). I'll update this thread as appropriate.

For those that have followed Cate&Rob 's plumbing threads you'll know that he incorporated "bomber doors" into his coroplast so he can access his dump valves and cables for cleaning and lubrication. He's often commented that some difficulties with cable operation is due to routing. That can only be fixed by dropping the coroplast and taking some of the bend out of their original installation location.

My dump valves worked OK right from the beginning (I've owned the camper about 1.5 years) so the current difficulty is not due to the initial installation. It's corrosion in the cable. There could be some problem at the valve itself, too. I also tried the canola oil trick I first saw on Youtube, so we'll see if it helps, too: https://www.youtube.com/watch?v=BFS0ry19tTU

-----------------------------
Howard, I could not not access your video as it says it is unavailable. Can you re-post it, or am I missing it elsewhere. I have reviewed Rob's impressive plumbing job and bomber door access. While that looks like a superb fix I find the thought of trying to re-create that solution on my rig a bit daunting. So Rob, how much would it cost for you to do this for others in your spare time? I tried the vegetable oil fix, but don't believe it'll work consistently for the reasons Rob outlined. Like many of you, I have to do something as one of my valves will no longer completely close which makes dumping an unhappy experience. Thanks for the tips everyone; I'll keep watching and report on any success I may find. Cheers, Jerry

[howson]

-----------------------------
Howard, I could not not access your video as it says it is unavailable. Can you re-post it, or am I missing it elsewhere. I have reviewed Rob's impressive plumbing job and bomber door access. While that looks like a superb fix I find the thought of trying to re-create that solution on my rig a bit daunting. So Rob, how much would it cost for you to do this for others in your spare time? I tried the vegetable oil fix, but don't believe it'll work consistently for the reasons Rob outlined. Like many of you, I have to do something as one of my valves will no longer completely close which makes dumping an unhappy experience. Thanks for the tips everyone; I'll keep watching and report on any success I may find. Cheers, Jerry

Jerry,
I still have the video but I must have removed it from YouTube as the method did not work. My fellow moderator, Cate&Rob (Rob) is much more knowledgeable, as you reference in your post, on this topic. Your time will be well invested if you engage him in a conversation about your faulty valves.

If you really want to see the video I'll put a copy in my DropBox and send you a link by private message. You can then download the file and play it on your computer. But there's nothing you'll see that will be of any help other than what NOT to do.

If you've ever read John C. Maxwell's book Failing Forward you'll understand why I try things like this...

Howard

P.S. Welcome to the forum!