4104 AIR SYSTEM ISSUES

[Jay52999]

hello im so grateful for this site im a newbie busnut I have a 56 4104 air system will not air up.... psi at wet tank gets to about 100 psi so compressor works fine, to get it home i ran a line from a spot in air line on fire wall all the way to aux tank and it airs up and maintained psi to get her home
Im posting pictures of where I hooked up temp line to aux tank what am I missing? Please help

[dtcerrato]

There is a blockage somewhere in between. By doing what you did solved your need for air but you need to back up to the wet tank & move forward. Before you ran the bypass did you have brakes? The wet tank check valve could be suspect. Working forward from the wet tank will get you closer to where the blockage is. There are purge valves at the bottom of your 3 on board tanks. Start by purging the wet tank then see if there's air to purge in the tank at the center near the front axle then your dry tank under the driver. That will help you find where the air stops...

[Jay52999]

No brakes before bypass . Wet tank good psi when i open drain valve hardly anything at next tank wet  tank has 2 lines upper and a lower is it the lower that's the out put goi g to next tank? What valves should I look for or try to clean out? Thanks for all the help! Also during the drive it started to build extreme psi on its own . For safety i ran a line in to cab from aux tank with a small air compressor running off the genny it started  building up to 140 plus my friend had to disconnect line from temporary compressor and bleed off tons of air to keep it in range. Strange . Im going to disconnect output at wet tank and try blowing thru it take off input and next tank and see what happens

[chessie4905]

With air pressure at zero remove petcock from tank with no exhaust. Could be plugged.

[dtcerrato]

What were the temps when it didn't build air? Was it below freezing? If so it could easily be a frozen wet area. BTDT.