Bendix brake valve question

[biscuits and gravy]

I don't know if you found the source of the leak yet. But if you haven't I can tell you I have had in the past my share also; with air leaks not in the normal places that temporarily drive me nuts trying to find them.

I would check to see if anybody replaced any parts before you started chasing the air leak. Maybe somebody else previously replaced something and reinstalled a couple of lines backwards.

I only mention this because I test drove my KW900 and liked it. It took a couple of days going back and forth to settle on a price with the seller. I went back and paid and picked it up.

Drove it home and the air gauges were indicating normal pressures at times and then at times it would only build to 70-80 pounds. Overnight it sat and leaked both tanks to zero.

Next day I chased after everything I could with soapy water and put on a new governor because I thought I had found the leak. I was wrong, I saw that there was a new drive axle load leveler valve on the truck earlier (but didn't soap it) that wasn't on it when I test drive it a few days earlier.

I called the seller and asked what was going on. He said it had a slow leak so he replaced it. I asked if he replaced anything else and he said no. I went back to the new load leveler valve and soaped it up and observed it exhausting a tiny leak. I wondered how this thing could be leaking if its brand new. Then I thought, what if the seller had the two air lines backwards. So I pulled the air lines and reversed them and the leak stopped. The air pressures then shot up and everything returned to normal.

Moving on from Krapworth and lets go to my Peteshit...

Chased my tail again with soapy bottle water spraying everything I thought might have an air leak. Short story, both tanks would leak over night to about 30-35 pounds. Discoverd my air blend door actuator was leaking air, then discovered after replacing it with a new one, that it leaked TOO. I then played with the master temperature controller and the air valve for the bilevel mode selector had a blown seal in it. I replaced that and it solved the mystery.

Moving onto one of my Interfucknationals....

Rinse and repeat again, no air leaks at the most common places so I peaked behind the dash to look and listen for air leaks and discoverd nothing. Went through my mental checklist and thought to myself I have not soaped up the air dryer. I then soaped it up and discovered that the flange mount bolts that circle the air dryer had several places around it leaking air through the bolt holes.i checked the bolts by trying to tighten them a little more and that didn't work.

I then removed the air dryer to inspect the inside. I discoverd that someone replaced the air dryer filter and reused all the o-ring gaskets. They didn't replace them and squirted a mess of silicone on top of them and bolted the air dryer back together. That silicone bandaid didn't work.

I replaced the entire air dryer with a newer updated air dryer and problem solved. I couldn't find replacement o ring sets because that model air dryer had become outdated. I believe the shop I paid to change the air dryer the previous 3 months or so before, discovered they couldn't get the o rings and just siliconed them. I don't know for sure, why they dropped the ball but they did. I always thought the o rings were automatically included with a filter.

Another thing that helps me chase air leaks is by blocking off one tank at a time and chasing the lines that are connected to that one tank to see each thing that tank supplies... while watching the air gauge for that tank. If that tank doesn't leak while I monitor the dash gauge for it. Then I've isolated the air leak to the other side.

I apologize in advance if my description above has wasted your time or confused you. Hopefully you've already found the leak before I posted this.

By the way, I have obscene names for all my trucks, but I still love'm. I think the trucks from International, KW & Pete that are about 5 years old and older are the better trucks out there.