I filled it with water and carried it in the truck all day to test for leaks. Something I noticed was it's sealed so well, it builds pressure as it warms up. I decided to put in a relief valve and it gave me an idea for a cleaning device.
I put in a multi-directional sprayer with a garden hose barb. When it's not being cleaned, I will have an adapter that threads on. It will have a shutoff valve and small line run outside the truck. This way I can equalize the pressure. This should be beneficial with the altitude change when we go in the mountains.