Older 379 air problem

casemanwcoh

New member
Have a 1996 379 exd. Truck doesn't get used much anymore. Started it up the other day and air builds normally. But I have no air to anything but brakes. None to bags, shifter, seat etc. Sure it must be a valve somewhere. Any idea what one and where? Thanks
 

Goodysnap

Well-known member
By your description it sounds like both your primary and secondary gauges build to normal pressure. Here's where to start. Check that all the tanks are full. Pull the drain valves and install mechanical gauges if you have to. This will also make sure your dash gauge is accurate and the pressures match. You will likely find one tank not filling. Make sure to check all the tanks.There may be a pressure regulator on the supply line mounted directly on the tank that is plugged or not letting air through. HTH
 

casemanwcoh

New member
Yes, both gauges are working normally. I have not put gauges on tanks, but have ports on 2 and they seem fully pressurized. Also have air to trailer lines. There is what I think is a valve mounted right off one of the tanks that I plan to check tomorrow. Trying to trace lines back to a common source, but it's a nightmare under there.
 

Truck Shop

Well-known member
Some of those tanks can be dual compartment. For the air suspension look for a pressure protection valve that looks like a tee fitting, it will have a red top on it.
See if you have air to that valve. It cuts air off to the bags when pressure drop below 70 to 80 psi. Those valves will freeze up from setting.

Welcome to HTF casemanwcoh

Truck Shop
 
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