Do i need a new air dryer?

[tree98]

I held a piece of cardboard over the end of the braided line coming out of the compressor going to the dryer, I held it there for about a minute with the truck at idle and absolutely nothing on the cardboard. No water no oil no goop, nothing

[Rockhwy]

Sounds like dryer needs serviced when servicing be sure to check the heater on dryer it heats purge valve when temp is 40 degrees and less. With ohm meter resistance should be 1.5 to 3 ohms when 40 or below

[Chamberpains]

Your compressor is probably fine then. The butterscotch goop is probably all built up over a long time plus all the airline alcohol and whatever else was dumped in the line to get it thawed out.

[Wiseman]

Cardboard over at the end of braided wire hose .....

That’s a good sign. Although doesn’t mean a lot , because air isn’t compressed and its temperature is slightly higher then ambient temperature. It’s physics at work .
Ambient air have relative humidity. In the southwest desert can be as low as 7% . In the mean time in Louisiana, Georgia, Florida can be as much as well over 90% .
What happens to your beer when you get it out of the fridge ? Sweats! Because of the relative humidity and big temperature difference.

[tree98]

I bought a brand new dryer and installed it. I figure now I don't have to wonder if another part of the dryer isn't working properly because now it's all new. I also poured a quart of airline antifreeze directly into the wet tank. I guess we'll see what happens now.

[tree98]

and the while we're on the subject of this truck.... Something seems up with brakes, new drums and shoes,the chambers, slacks and s- cams/ bushings all good. The brakes work and the truck stops but it just seems like you have to step on the pedal a lot harder than you used to have to. Is there a way I can check the air pressure to the chambers ? or what else should i check? It's been like this for about a year

[Chamberpains]

That water and goop thats in your dryer doesn't all stop there when the dryer is that plugged up. Plus Bottles of airline antifreeze.... That's some seriously bad stuff to have run thru the system and be all over every valve in the truck. You probably need to go piece by piece and give a little TLC to everything in the air brake system. Airline alcohol dries the lubricant in brake valves, water corrods metals in brake valves, oils (engine oil) other than the ones that are supposed to be in the valves cause rubber seals to swell, Dirt and dust bind up moving parts... You can see why keeping dry clean air to the brake system is VERY important.

Yes, you can test the air pressure input to each brake chamber by hooking an air guage in at each brake relay valve output to the chambers. Its usually a 2 man job. 1 to operate the pedal and 1 to watch the gauge. It can be a 1 man job if you make your gauge with a long enough airline to go from the valve to the cab where you can press the pedal and watch the gauge at the same time. But you will get a little gauge lag because the air has to travel thru all that airline to gauge.

Hers a good video how the valves work and why its needed

https://youtu.be/f3LD8M0HKjo

You need as close to 120 psi out each side of the valves to get equal braking to each side. If its unequal or never gets up close to max air pressure the valve is not working properly. Relay valves are pretty cheap. Replace it.

Heres a good video of a guy pulling 1 apart and you can see the crap that gets in them.

https://youtu.be/IQLvDEnFx90

Now another part that is almost always overlooked because it is usually ridiculously hard to get to, is the treadle valve. But they very often go bad and or clog or corrod. Causing all kind of poor braking problems.
Heres a video (caution.. its a snoozefest but VERY good at showing what and how treadle valves work.) You'll see why dirt water and gunk can easily screw these up. The video is of a Bendix valve but almost all of them work very similar.

https://youtu.be/WTXtyxqvDtY

There's more ABS valves and other check valves that can go bad and need to be checked but these are the main culprits in braking failures if all other mechanical parts are in good working order.