Air suspensions are gaining popularity every day. Installing a set of airbags or air cylinders can be simple enough to be installed at home, but it's important to do it right. One of the safest add-ons that you can make to an air suspension is adding check valves. A check valve allows air to only flow one way in an air system. Why is that important? Because if for some reason you lost pressure in a line, the entire air system would not evacuate, allowing you to either pull over to the side of the road, or get a jack under the truck to fix the problem. Installing check valves isn't complicated; it just takes some time.
There are two different types of check valves that can be installed in an air suspension, the only difference is how they mount. One style has male pipe thread on both ends, and the other has female pipe thread on both ends. Depending on how your air system is plumbed, one of these may be better than the other; it just depends on your specific setup. We'll start with a completed valve assembly and, for this example, will be using the male pipe thread style check valves.
Start by removing one of your valve assemblies from the vehicle and setting it onto a work bench. Make sure you know which valve in the assembly is the lift valve and which is the lowering valve.
A typical valve assembly has a valve, then a t-fitting with an airline mounted at the bottom of the t, then the dump valve. Between the valve bodies and the T are male pipe thread straight fittings. Place the lift valve in the bench vise.
The check valve needs to be installed after the lift valve and before the t-fitting that feeds to the airbag or air cylinder. Why? Because if we lose pressure in the tank or into the airline that feeds into the valve assembly, we want to keep pressure in that airbag or air cylinder. Using the wrench, remove the straight fitting that goes between the t-fitting and the lift valve. You may have to move the assembly around in the bench vise to get better access.
Prepare the check valve for installation by putting a few drops of Loctite 545 on both ends of the check valve threads. You could use Teflon tape, but sometimes Teflon can foul valve bodies. The Loctite also gives a very good seal.
The check valves have a direction that they flow, which is marked on the fitting itself. Make sure the airflow direction is going towards the t-fitting; otherwise, the check valve will stop the air from moving further than the lift valve. Thread the check valve into the valve body. You want to make sure its very tight, so it keeps a tight seal.
Thread the t-fitting into the check valve, also making sure that it is very tight.
Reinstall the assembly in the vehicle and move on to the next assembly.
