Does ctis moisture trap always blow air?

[SUPERSPORT]

I have a 1990 M923A2.

Under the dash toward the passenger side is a small black moister trap. From what I can figure by looking at it and reading the TMs its part of the CTIS. Am I correct?

It spews air constantly and it's loud. Is it supposed to? It drives me nuts. If that's what it is supposed to do it should be outside the cab.

When I shut the truck off it keeps going and drains my primary tank pretty fast. If I stop at a store real quick I have to set there and build up air again.

Should it constantly blow air? That much air? If so I'm going to add a line and route it out of the cab.

 

[davo727]

I don't think so, neither of my A2 do that .

 

[5tonman1971]

Not it's not supposed to do that. It may have a crack in it.

did you ever get your cover figured out?

 

[SUPERSPORT]

No cover yet. You?

 

[Roo]

It is possibly the little O-ring in the bottom of the bowl. You can try to fix it or just by the whole thing new. You can get one from mscdirect.com for $45
MSC Part #:01780204
Mfr Part #:F07-200-A1MA

 

[5tonman1971]

No cover yet. You?

Sorry that was a typo, It was supposed to say cargo truck, not cover.

we seen you go past the fuel station and never heard from you since so I'm assuming all went well.

 

[searls84]

It is possibly the little O-ring in the bottom of the bowl. You can try to fix it or just by the whole thing new. You can get one from mscdirect.com for $45
MSC Part #:01780204
Mfr Part #:F07-200-A1MA

Or just put some JB weld or epoxy on the hole in the bottom. Quite a bit cheaper..

 

[camoyj7]

Is it facing down or is it sideways?

 

[SUPERSPORT]

Sorry that was a typo, It was supposed to say cargo truck, not cover.
we seen you go past the fuel station and never heard from you since so I'm assuming all went well.

Yea, we went to the Kroger down at 33 for fuel. I've talked to Darrell several times. Trip was great.

 

[SUPERSPORT]

Is it facing down or is it sideways?

Down.

 

[RustyM923]

Just as a matter of reference, if you have your air dryer working properly, you'll likely never see any water in that separator.

If you bypass the dryer (or don't have one working properly), you'll get moisture and have to drain that little bowl periodically.

I think it's a relic from the pre air-dryer days.

 

[hklvette]

When I got my 931, the seperator was leaking. What I found was that there is a little umbrella seal in the bottom of the unit that was installed upside-down. If you unscrew the bowl, there's a piece of white plastic inside. On top it should have the seal with the lip facing toward you so the pressurized air pushes it against the bowl. If the lip faces the bottom, the air pressure will rush past it. Also, there's a little spike that goes through the bottom of the bowl that looks like you can push up on to blow any water out without taking the unit apart.

 

[Roo]

Or just put some JB weld or epoxy on the hole in the bottom. Quite a bit cheaper..

That would stop the leak, but would disable the auto drain. When I fixed mine I plugged the leek until I got the new part, 1/8th tank of diesel costs about the same.

The image is the filter with a clear bowl so you can see how the parts go inside of it.

 

[SUPERSPORT]

I took it apart and cleaned it out real good. The little umbrella thing was stuck open. Probably from setting around. Anyway it works fine now. Thanks guys.

 

[mikey]

Don't discount what Rusty said. Mine was spewing air until I rebuilt my air dryer. Has not vented ever since.

Mine started expelling air BEFORE the air dryer purge valve got stuck open. Keep an eye on that purge valve when the truck is running from time to time. Your air dryer may be in the early stages of failing.

Mikey

 

[foprange]

My m923a2 is doing the same thing, hissing loudly as I drive. Took it apart and did not see anything broken or cracked... The picture of the new dryer appears to have an oring at the bottom of the drain cup where the point of the small shaft pokes in. I did not have that oring on mine when I took it apart. Is there supposed to be one? I have not seen an exploded view in the TM to answer that question.

 

[Roo]

Yes there should be an O-ring. The O-ring on mine was in several pieces in the bottom of the bowl.

I found the exploded view in TM 9-2320-272-24P-2 Figure 621