M939A2 Front Tire Hissing Sound (CTIS)? Video

[PapaPumpSD]

The big rig has a hissing front right tire. Around 70 psi (primary air pressure gauge) the hissing starts. It's intermittent (it'll stop hissing for some reason, then start again). Here's a video. Unfortunately the noise of the truck is masking much of the hissing noise but you can hear it if you listen carefully. Any ideas? I'd like to fix this. The tires do NOT go flat. It seems as though it is tied to the CTIS.


https://youtu.be/oVk05_rXc1w



Thanks for your help,

Brent

 

[86m1028]

No video

 

[PapaPumpSD]

No video

Hmm, that is strange as I just clicked on the video and watched it. Do you not see a YouTube embedded video or do you see one but it doesn't play?

Thanks for the heads-up,

Brent

 

[86m1028]

Says must sign in to view

 

[PapaPumpSD]

Says must sign in to view

Ok, thank you. I changed a setting in YouTube. Would you try it now and let me know?

 

[86m1028]

You got it, it works now.

Pull that guard & check your hose connections.

 

[PapaPumpSD]

You got it, it works now.

Pull that guard & check your hose connections.

Ok, will do. Thank you!

Brent

 

[Jbulach]

You got it, it works now.

Pull that guard & check your hose connections.

Soap everything, it's not on the hose side of the wheel valve if your tires not going flat, unless theres a valve core in your stem.

Hopefully just the o-ring on the adapter...

 

[PapaPumpSD]

Soap everything, it's not on the hose side of the wheel valve if your tires not going flat, unless theres a valve core in your stem.

Hopefully just the o-ring on the adapter...

Well, regarding valve cores, I had one in my rear-left tire. My suspicions are there are valve cores in all the tires but I haven't verified that.

 

[Jbulach]

Very likely.
If a CTI leak is big enough for you to hear you should be getting five a flashing lights and it should kick off.

 

[PapaPumpSD]

Very likely.
If a CTI leak thats big enough for you to hear you should be getting five a flashing lights and it should kick off.

Yes, the CTIS has 5 flashing lights. It never functioned properly and my suspicion was that there were valves in all the tires. Are you saying that there is probably an air valve in that hissing tire and that's from the CTIS system trying to push air into the tire but it cannot due to the air valve. As a result, the air is escaping?

 

[Jbulach]

The valve cores were likely added after the system developed a leak, that is all that you have to do to eliminate the system.

Pull that cover and it should be obvious where the air is coming from, take a picture point out the leak and post it up.

If you fix your leaks and you will likely be able to get your CTIS functioning again, before everybody tells you to scrap it

 

[adamsoffroadperformance]

most likely loose hose or bad oring where the tube sticks out through the drive cap.

 

[PapaPumpSD]

Ok, Here's a photo of my front right wheel w/the protective cover off. I see two valves stems there ("1" and "2" as I indicated on the photo).



Question:
1) Is valve stem "1" the stem in which I can remove the CTIS hose to manually air up the tire?
2) What is valve stem "2" for?

I'm trying to understand what I'm looking at so I went to the manual TM 9-2320-272-24P-1.

3) Can someone let me know what the object is that I circled in blue in the attached photo fom the manual? I couldn't find where that piece was identified.

 

[MtnSnow]

Valve stem #2 is where you manually add air to the tire when there is no valve stem in #1 (factory working CTIS setup)

When removing the CTIS system you pull the Valve stem from the #2 position and place it in #1 position and then you add air to the wheel just like a normal truck.. If your wheel in question already has a valve stem in #1 position then there is no need to have the hose from the CTIS valve to the wheel or the CTIS valve to even be on the wheel.

 

[PapaPumpSD]

Thanks MtnSnow. Let's assume there's a valve stem (insert) in position #1 and #2. Could I air up the tire manually on #2 position? I THINK all the tires have valve stems in them which is knocking the CTIS' functionality out.

Valve stem #2 is where you manually add air to the tire when there is no valve stem in #1 (factory working CTIS setup)

When removing the CTIS system you pull the Valve stem from the #2 position and place it in #1 position and then you add air to the wheel just like a normal truck.. If your wheel in question already has a valve stem in #1 position then there is no need to have the hose from the CTIS valve to the wheel or the CTIS valve to even be on the wheel.

 

[Jbulach]

The valve core has to be out of position 1 before you can use position 2 valve stem for anything.

If you have a valve core in position 1, then yes, you can remove the CTIS hose and fill the tire there.


The object you have circled on the TM page is the "Wheel Valve"