Hmmm...air leak.

[dhirocz]

...or go go advance Auto and spend $30 on a handheld detector and an 8oz bottle of dye. I'm sure that's alot cheaper than that kit...

[hhow55]

Found the complete kit for this price
https://www.oreillyauto.com/detail/trace...eak+tester

[dhirocz]

Ok so I'm getting annoyed here.

I have a bunch of small air leaks. I'm taking the truck with me to the hose shop when I go home on my 34, in order to get some of these fixed, and I will just remove and replace the leaking fittings on site...

However, I have found that I cannot find my air check valves to save my life. Every schematic I have found puts them on the inlet of my primary and secondary tanks. In fact, the system isn't even plumbed the same as every schematic I've seen.

I know that the primary tank is the one that will not hold pressure at all when the supply tank is vented. The secondary tank holds, though not well. I considered the possibility that someone removed them entirely, but then I would expect the secondary to bleed down immediately like the primary. I think the check valves are elsewhere, and I'm just not seeing them though I've already looked twice.

My local dealer has not been able to help me with an air brake schematic of my truck. Anyone know of an online resource that would have KW schematics like these?

[Nilao]

If it is like my friends peterbilt the check valves are in the body of the air dryer. There are none on the tanks. There will be one from the dryer to the primary tank and one that feeds the secondary tank.

[dhirocz]

That's where I thought they might be...but no, they aren't there either.

[Nilao]

(11-10-2017 )dhirocz Wrote:  That's where I thought they might be...but no, they aren't there either.

Are you certain? If it is the AD-IS air dyrer it has an aluminum body with a screw on type filter. If that is the model you have the check valves are located under the 4 black plastic caps beside the purge valve.

[dhirocz]

Well that got my attention. Yes I have an AD-IS dryer. As a matter of fact, I had to replace the entire assembly last year when a buddy of mine and I ended up ripping the threads off of it entirely when removing the filter. I doubt it was ever changed before I got it...the wet tank was very...well...wet.

Didn't help that at some point in time the truck lost it's main driveshaft and apparently took out the tank. It was replaced, and the new one was tilted away from the drain instead of towards it. I still remember the rusty water and muck that was in that tank I had to flush out as a result of that. Now I'm wondering if this is related?

Still did the same thing before the change compared to now, only difference is the system stays dry and it actually purges now.

Are those valves cleanable/user serviceable? I'm about to go dig the old one out of my scrap pile and take a quick look when I get home. My dryer is under the cab.

[dhirocz]

So I just spent some time looking into my dryer more. Apparently it's acting as intended, and there are no factory installed check valves. That's news to me. I did see a schematic saying I could add one.

The info in the dryer says it will only let one side bleed down, and the other should stop at 70 psi, which it does.

Since my air supply comes off the supply tank (the valve I use to pressurize tank trailers to unload) which also drains the primary tank, it looks like I'll add a check valve in between. If it then drains the secondary, I'll put one there too. To double check myself I'll give Bendix a call on Monday to make sure this doesn't interfere with the operation of the dryer...they only show the 'optional' check valve on one tank, not both.

No factory installed check valves...wow. Thanks for pointing me in the right direction!