My driver's seat keeps sinking down

Your truck is designed to keep air pressure up while driving
Brakes take way more air than the seat
If you are losing that much air from an outside source the seat is the least of your problems and I’m guessing that you would lose enough to sound an alarm and have the brakes lock up before the seat would drop

I would look around the seat itself, it takes very little air and you might not hear it like a leaky airline outside

 

You may have a leak at the up/down switch for the seat or an airline that supplies the seat. If the truck's air system leaks enough air the driver seat will sink. You need to watch your air pressure gauges as you drive to see if you are losing air in the whole system or just in the seat. EVERY truck will lose all of its air if it sits long enough. When you do your pre-trip inspection and check your air system does it seem to be losing air faster than the DOT standard allows?

 

That’s what it is. Mine does it all the time.

 

Which makes sense but he said drops while driving which changes the possibilities

 

Thanks for the heads up!! Ill check it out lol

 

The air in your seat should not be affected by the air in the rest of your truck. You should be able to completely empty your air tanks and the seat shouldn't move. Seat is operated by an air switch and the air shouldn't be able to bleed back into the system when system pressure drops.

Long story short you probably have a leak in you seat circuit. Either the switch or line or bag

 

Mine was doing this very often. Figgered out the cause was the seat valve. Removed valve and disassembled to find nothing inside but 2 small o rings. Put white lube on O-rings and switch slide and reassemble. Seat stays up.

 

The leak around fifth wheel after dropping a trailer is air exhausting out the leveling valve. When the trailer is dropped the bags pick up due to no weight on them. That signals leveling valve to release some air till they are at proper height.


As mentioned the seat switch keeps the air in the seat air bag from bleeding back into the truck. A bad switch their could raise the seat as well as lower it due to the side with the most pressure wins. It’s gonna be a line or the bag itself in the seat

 

If you keep the area under seat cleaned out it will keep sharp trash from poking holes in the air bag that holds up the seat?