new to RVing and my discharge line seals are beginning to malfunction.  How do I change them out

Welcome to the Escapee forums. I am not sure exactly what you are asking about. Are you dealing with a leak from your waste tank dump valves? More information will probably help us to give you good advice? The dump valves for your waste tanks are removable and you can replace them fairly easily as long as you have reasonably good access to them. 

My dump valve seals are not contained and are beginning to not close properly

Unless they are different from all the ones I've seen they do not have seals. Not like you imagine anyway. They may get crud built up on the valve disk which keeps them from closing all the way. There are two solutions, very thoroughly flush the tanks. Wear rubber gloves, remove the valves, clean them up, I lubricated the disks with silicone grease, and put them back in. They worked fine after that.

Or buy new valves and remove the old ones and install the new. There are temp fixes where you can buy a valve that hooks onto the outlet of the piping. Then you use that to shut the line off.

You can see what the valve looks like. I'd call this a knife valve.

Edited December 6 by agesilaus

I agree with the post above. If they are leaking you probably need to replace them and this isn't difficult or expensive, if you have reasonably good access to them. There are two of them and they are not the same size. The valve for the black tank is 3" in diameter while the gray tank valve is 1.5" in diameter.  They look pretty much the same except for the size.

  On 12/4/2019 at 9:07 PM, Kirk W said:

The dump valves for your waste tanks are removable and you can replace them fairly easily as long as you have reasonably good access to them. 

Kirk supplied good links in his second post.

However - -   "..........you can replace them fairly easily, as long as you have reasonably good access to them".

The "good access"  may be *VERY* difficult access!  In the good old days, the valves *were* easily accessible - usually *externally* on the 3" drain pipe....reach down,  pull the valve = EASY access!

Depending on what type of RV you have, the valve may be *WAY* underneath the RV, and may have a  cable (or electric) actuated valve - rather than the "pull handle".  Replacement requires you (or the installer) to be underneath the RV.

You didn't say what type you have - Often the problem is the cable connection FROM the pull handle TO the valve. - or the valve is not actuating (electric) for whatever reason.

It is definitely *NOT* easy access!! - Nor is it an easy job to replace it!  - Been there, done that!

As others have suggested - try a thorough flush - or multiple flushes.  Some folks suggest adding some veg oil in the water (do not use drain cleaners).

If it's a cable type - don't try to force the cable!  Hard "pulls" (or "pushes") on the cable  -to try to make the valve operate-  may have initiated "play" in the connection - or a kink in the cable.  Mfgrs can be sloppy about the mounting - which allows kinks to be "forced" after years of use.

If you don't have any success with that......replacing the valve is necessary.  Yes, you could replace *just* the seals - but that requires removing the valve anyway.

Google "Valterra Waste Valve" - on the mfgr's site go to "Waste Valves and Accessories".

A quick and easy solution - is a Valterra "twist on" valve - which you add to the end of the 3" drain pipe. You then attach a cap or the drain hose (when it's time to drain) as you do now.  (Every RV'er should have one - cheap insurance!).

Lastly - there are YouTube videos which should help understanding the valves & the process of replacing them. (Google should give you "hits" to those).

Ask one of your neighbors!  - If they have waste and gray water tanks - they gotta know, LOL.

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Edited December 12 by Pappy Yokum

We have replaced them - while it was probably easy to install before the rest of the motorhome was built around it, it is down right HARD to replace.   Took us from 10:00 am to 4:00 pm to finally get it all done and cleaned up!  And when people see you working on your wet bay, especially the tanks, they will cross the street and way to make sure they are away and don't have to offer to help! ?

Bingo !! - ( I) Should have linked this one.....

GREAT  (Youtube)  VIDEO -  - "All you need to know" -

"RV Waste Valve Repair & Maintenance by RV Education" -  Valterra (10minutes!)

http://www.youtube.com/watch?v=toD1epBKjnc

...don't forget, click where indicated  to-  "skip ads" !

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Edited December 12 by Pappy Yokum

  On 12/12/2019 at 2:52 AM, Barbaraok said:

while it was probably easy to install before the rest of the motorhome was built around it, it is down right HARD to replace.  

I guess there is some advantage to our current, seasonal RV as the dump valves on it are very easily accessible. They are about 18" in from the edge of the RV and in the open. When I changed one of them on our previous motorhome, those were inside of a wetbay but once some cosmetic panel was removed they too were not that difficult. Removing the panel was the most difficult part. But I also once assisted a friend in the same job on his fiver that used cable pulls for the dump valves that was a really nasty, all day job with two of us working. 

  On 12/12/2019 at 5:56 AM, Kirk W said:

I guess there is some advantage to our current, seasonal RV as the dump valves on it are very easily accessible. They are about 18" in from the edge of the RV and in the open. When I changed one of them on our previous motorhome, those were inside of a wetbay but once some cosmetic panel was removed they too were not that difficult. Removing the panel was the most difficult part. But I also once assisted a friend in the same job on his fiver that used cable pulls for the dump valves that was a really nasty, all day job with two of us working. 

MIne is hard to access also. Thankfully the extended service contract paid the bill to replace all three leaking valves, except for the $50 deductible.

Edited December 13 by Ray,IN

This conversation makes me think that it could be that we should consider the ability to access things which could need repair when we shop for an RV. As one who made a career in service and repair work, it has always been one of the things that I look for, but I'm not so sure that I have ever mentioned it as a consideration for a person new to buying an RV. 

I guess you need to consider freeze proofing. Getting all wet lines up inside the belly Coreplast. At least on the 5ver I worked on they were under the Coreplast but within a foot or so of the side. Burying them deep inside the belly is a real problem. But how would you know when buying a unit? I doubt a dealer will willingly pull the belly off for you to look. And I have never even heard of a piping diagram of one of these units.

  On 12/12/2019 at 5:56 AM, Kirk W said:

 But I also once assisted a friend in the same job on his fiver that used cable pulls for the dump valves that was a really nasty, all day job with two of us working. 

I did that job - under a fiver - and it's way worse than being under your car or truck.   Raising the 5er doesn't help a whole lot.  It was on concrete with lots of space. (Didn't matter).

Sooooo - I added another (secondary & accessible) pull valve in the 3" line, closer to the termination point and easily replaced should the need arise.

*If* the "main" valve leaks - it can just leak - or stay open!

A "twist on" valve is in the storage bay - as back-up to the back-up.

Moral of the story (stories):  Take excellent care of your plumbing.

BTW - never had any parts/repair insurance on any of the RVs I've had- since 1975!   Never needed any.  My 5th had 2 years (factory),  but the valve problem was long past 2yrs.

Guess I'm money ahead on that one......but  (one time?) "PITA Repair" ins would have been nice!

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I abandoned the valves buried in the belly installed by the manufacturer. They are left open. I added new valves to the pipes on the exterior of the rv. Easy to repair and use. For your leaky valves, try adding 1 cup of cooking oil to each tank after you empty them. It will lubricator the blades and seals. 

Abandoning the interior valves in favor of adding exterior valves may bite you later.  Sometimes you can't avoid being in freezing weather.  A few years ago, we were headed south and ran into freezing rain on I-10 between NOLA and Houston.  We were lucky to duck into a campground just before they closed the interstate, and had two mornings with temps in the teens.

There are reasons those valves are buried......