How to Clear a Leaking Dump Valve

Professional Tips for Safe Dump Valve Handling

As a driver at Service Sanitation, nothing can be more intimidating than the 4” dump valve on your pumper truck. This valve is often located on the driver side of the vehicle and is used to empty your truck’s waste tank each day. Equipped with a blade valve and a steel cap, this valve is what keeps the 1000 gallons of waste in your truck from spilling out onto the ground at any given time. At the end of each day, either you or a yard employee will be required to dump your vehicle from this main valve. If this process is done incorrectly, a slow leak situation can occur from either a loose cap or a valve that isn’t fully closed.

Activate Your Truck’s PTO 

To begin, we’ll want to activate the PTO on our truck, ensuring it’s in vacuum mode. I repeat, you MUST make sure your truck’s PTO is on Vacuum and NOT pressure or you’re going to have a really bad day. After we’ve confirmed this, we’ll head back to the cab and grab our rubber gloves, a towel, and a 5-gallon bucket.

As vacuum pressure is building inside the tank, we’ll want to place a 5-gallon bucket under the valve. Next, we’ll slowly remove the cap by prying back on the two cam locks and twisting off. As you’re doing this, expect a small amount of wastewater to drip out and into the 5-gallon bucket. Once the cap is removed, we’ll wipe down the inside of the valve and anything that may have spilled onto the ground.

Clear Stubborn Debris Safely

Next, we’ll take hold of the dump valve lever and quickly open the valve allowing air pressure to rush in and clear any residual waste or debris that may still be in the line preventing the valve from getting a good seal. When opening the valve we will want to position ourselves at a good distance and to the side and not directly in line of the dump valve. This will protect us from the loud volume(noise) as well as from any waste that may expel from the valve.

When doing this, it’s important that we only keep the valve open only for a few seconds. This is because it is a large valve and allowing too much air into the truck at once will eventually cause the truck to lose suction and we risk a large amount of wastewater to spill out from the valve.

Ensure Leak-Free Operation 

Once we’re certain the valve is clear, we’ll keep the PTO running and make sure the valve is fully closed. We’ll know it’s closed because we won’t hear any hisses or suction sounds from the valve. Next, we’ll place the cap back on the valve, ensure the O-Ring is still in good condition and the cap sits flush on the valve. We’ll then make sure both cam locks are secure. This should fix the leak! Before shutting the PTO off, we’ll need to suck up the waste in our bucket back using the truck’s wand.

At this point, we’ll want to check the valve for any more leaks. If the truck continues to leak, you’ll need to contact the garage and await instructions. At this point, the valve may need to be replaced. If all checks out though, you can continue on, periodically checking it to make sure all is well.