Sticky RV Waste Tank Gate Valves
It happens to all RV owners sooner or later. The gate valves that open the black and grey tanks start to get difficult to open and close.
After a while, it starts to feel like you won’t be able to open them at all.
Related Product: Install Valterra Electric RV Gate Valves (click to view on Amazon) so you never have to struggle to open holding tank valves again.
On our old travel trailer, I even ripped off the plastic handle to the black tank valve trying to get it to open.
Little did I know there’s actually a simple fix to this issue that will also help keep the valves opening easily in the future.
How Do You Lubricate an RV Gate Valve?
There are two moving parts on RV gate valves. The handle that pulls or pushes the gate, and the gate that holds or releases the contents of the holding tank.
The handle will either be connected directly to the gate or it will be connected to a long cable that leads to the gate valve that’s located further away.
The cable style RV gate valve is usually found on large RVs that have the black and grey tank on the passenger side.
Because the valve needs to be connected at the base of the holding tanks, these cable gate valves are used so the handle can still be by the waste outlet where you connect the sewer hose.
See Also: Best RV Sewer Hose Kits Reviewed & Rated
As a side note, the cable can get messed up sometimes. If you’ve tried the suggestions below and the gate valve is still sticky or stuck closed it could be an issue with the cable and not the valve.
Some say that the best way to lubricate a sticky black or grey tank valve is to use WD-40 on the handle and inside the box that holds the gate valve when it’s open.
I suggest using water resistant WD-40 Specialist (click to view on Amazon) on the handles, but it won’t work as well on the inner gate part.
It is especially hard to spray lubricate into the gate valve if your RV uses a handle connected to a cable with the gate valve located somewhere further underneath the RV.
This is where RV drain valve lubricant comes in handy.
RV drain valve lubricant is dumped into the grey and black tank. It flows through the waste plumbing system and into the holding tanks.
Finally, it will settle on the RV gate valve from inside the tank. It not only gets lubricant all over the gate valve but on the walls of the holding tank as well which helps stop waste from sticking to it.
Lubricating from the inside of the black and grey tanks is the best and easiest way to do it.
I recommend using the Thetford RV drain valve lubricant reviewed below. It’s effective and safe for RV waste systems and holding tanks.
Best Drain Valve Lubricant Review
Thetford makes a lot of RV products, including toilets and portable holding tanks.
The company specializes in RV waste systems, and its RV drain valve lubricant is the best way to make it easier to open RV black and grey tank valves.
It’s also a great way to prevent RV gate valves from getting sticky in the future.
Made with a special biodegradable formula, Thetford’s gate valve lubricant is safe to use in RV plumbing and holding tanks.
It’s also safe for sewers and ok to dump at RV dump stations.
To use, dump the RV like normal. Then, with the gate valves closed pour 1/2 a cup in the toilet and the sink that is the closest to the grey tank.
Wait for 10 minutes to allow the lubricant to flow down the plumbing lines, into the grey and black tanks, and settle on the gate valves.
Next, you want to get the lubricant around the sides of the gate as well. To do this open and close the valves to the black and grey tank a few times.
This gets the lubricant inside and around the valve.
That’s all you have to do. The black and grey tank valves should no longer be sticky.
You can now continue with your regular RV waste tank checklist. Like adding water and treatment to the black tank.
Each bottle of Thetford RV drain valve lubricant has 24 fl. oz. of lubricant. You use 4 fl. oz. for each tank. That means you can treat both the black and grey tank valves 3 times per bottle.
Use this lubricant at the start, middle, and end of the camping season to maintain the gate valves so they open and close easily all season long.
What to Do If RV Black or Grey Tank Valve Is Stuck Closed?
RV drain valve lubricant is to be used when the RV holding tanks are empty. But what if the valves are stuck closed and you have full holding tanks?
This situation is something every RV owner fears, and it can sometimes be difficult to solve.
There’s no guarantee any of these things will work, but they are worth trying if you need to get those drain valves open to dump your RV.
Add Thetford RV Drain Valve Lubricant Anyways
Even though it’s meant to be used on empty RV holding tanks there’s a chance RV drain valve lubricant will work anyways.
The lubricant is heavier than water which means it can sink to the bottom.
If you add enough of it to the holding tank that has the gate valve stuck closed it might be able to work its way to the bottom of the tank and the gate valve.
The odds of this working are greater in the grey tank but it could still work in the black tank as well.
Try adding more than the recommended dosage to increase the chance of it getting to the valve.
You can dump in the entire bottle if you want.
Driving around with the lubricant in the tank will help it sink to the bottom faster. Wait as long as you can before trying to open the stuck black or grey tank valve again.
Dish Soap & Water
If you don’t have Thetford RV drain valve lubricant on hand another thing you can try to lubricate the RV gate valve that’s stuck closed is dish soap and water.
The idea is that the dish soap will be able to clean around the gate valve to loosen up whatever is making it impossible to open.
First, dump a bunch of dish soap into the holding tank that has a stuck valve.
Then dump in as much water as you can. If the tank is almost full you might not be able to add any extra water, but that’s ok.
Leave a little space in the tank so the liquid and waste inside can slosh around and mix up the dish soap.
After adding the soap and water drive around to get the waste inside the tank mixing.
You want the dish soap to reach the gate valve at the bottom of the tank.
This method is kind of a long shot, especially if you’re trying to unstick the black tank valve.
It’s worth a try though, and if you use a ton of dish soap it might be able to work its way down to the valve.
Drill an Access Hole in the Stuck Gate Valve
Some RVers use this next trick on the black and grey tank valves so they can lubricate them from the outside whenever they want.
It works well but it’s not my favorite method for regular maintenance because it involves drilling a hole in the gate valve housing.
But if you’re in a tough situation with an RV holding tank valve that won’t open when you need to dump your RV it’s a simple trick you can try.
Another great thing about it is you probably already have everything you need to do it on hand.
Part and tools you will need:
- 1/8 inch drill bit
- Can of lubricant (preferably waterproof silicone like WD-40 Specialist (click to view on Amazon))
- Screw to plug hole
A hole needs to be drilled in the front of the gate valve above the handle.
Once the hold is drilled put the nozzle straw that came with the can of lubricant into the hole and spray lubricant inside the gate valve until it’s filled with lubricant.
Plug the hole using a small screw so no waste water comes out of it when the valve is opened.
Let the lubricant sit for a few minutes so it has time to work on the gate inside the valve.
Try and open the valve again. It might still be pretty hard to open but hopefully, enough of the lubricant was able to get inside the valve to loosen it.
If you can get it open, dump your RV. Then remove the screw and fill the valve with lubricant while the gate valve is open.
Replace the screw, then open and close the black or gray tank a few times to get the lubricant all over the valve.
Undo the Valve Bolts a Little
If all else fails you can try loosening the bolts that are holding the gate valve together to release whatever is keeping it closed.
This trick could get very messy, especially if you are working on the black tank valve.
But if nothing else has been effective this could work as a last resort.
When you loosen the bolts that are holding the gate valve together only undo them about a 1/4 turn at a time. Also, make sure you loosen all 4 bolts so it’s being undone evenly.
If the bolts get removed all of the ways the gate valve will fall open and the contents of the holding tank will come spilling out uncontrollably. So make sure you don’t undo the bolts too much.
Try and open the gate valve every time to loosen a bolt a little bit. Hopefully, the valve just needed a little space and it opens after just a few turns.
If this trick doesn’t work it may be time to head to an RV repair shop.
Conclusion About Fixing Sticky RV Grey and Black Tank Valves
Proper maintenance is the best way to keep the gate valves to the RV holding tanks from getting sticky, hard to open and close, or stuck.
Use Thetford RV drain lubricant regularly and make sure you are using RV black tank treatment and plenty of water after dumping.
If you like the hole drilling method make sure you spray lubricant inside the gate valve once or twice every year to keep it working correctly.
Have any more questions about fixing RV black and grey tank valves that are hard to open and close? Leave a comment below.