M923A2 CTIS Problem

IanW

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Ok. Thanks guys. I'll hook it up to shop air and see if that helps. All tires are currently sitting at 13-15psi
 

1 Patriot-of-many

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Hey guys. New to the forum. I have a M923a2. We put 1600's on it. System worked fine, but one tire has a slow leak. I didn't drive the truck for a few weeks and the tire got pretty low (didn't check pressure). It would attempt to air it up for a few min, then I would get flashing lights. I read in this thread to press emer and run flat at the same time and it would pressure the tires down to the same pressure, then inflate them back up to whatever setting I choose. All the tires deflated, but now the system attempts to air them up, but fails to do so. I'll get a steady light on the emer and the mode I select. Anyone have an idea what is going on? Thanks in advance.
Don't where you got the idea you had to deflate...Push the bottom button only for a second or two as another noted
 

Jcbawn

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I searched HI and LOW for the leak with no luck. Turns out someone put a regular bolt in place of the banjo bolt at the rim. I will need to drill out the bolt as I can't find a banjo replacement, but i'm pretty sure this was the problem..
 
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Jbulach

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I searched HI and LOW for the leak with no luck. Turns out someone put a regular bolt in place of the banjo bolt at the rim. I will need to drill out the bolt as I can't find a banjo replacement, but i'm pretty sure this was the problem..
Can you post up a picture of the banjo bolt you are talking about?
 

Jcbawn

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This is from an m1081. The "banjo bolt" on the left was from a funcitoning tire, the bolt on the right came from a tire/rim that would deflate when the system pressurized. Not sure why they put the wong bolt in, but this is the way it came...
image1.jpg
 

IanW

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I took off one of the inflation valves on one of the wheels with a leak and the valve is female compression. The adapter from the wheel that it attaches too is also female. Is there a male adapter that is supposed to be there? Don't see how it could seal otherwise.
 

Andyrv6av8r

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I took off one of the inflation valves on one of the wheels with a leak and the valve is female compression. The adapter from the wheel that it attaches too is also female. Is there a male adapter that is supposed to be there? Don't see how it could seal otherwise.
You need to post a picture of what you're talking about. Are you referring to the tube that comes out of the axle hub that the wheel valve slides over?
 

Andyrv6av8r

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Yesir. Both female flares. I cannot figure out how to post a picture. Otherwise I would
So if it leaks at the compression nut, is it stripped and loose or does it tighten down? They strip VERY easily especially with an 1 1/8" wrench. If it isn't stripped, either the rubber seal inside is missing or worn out. I made new ones from 5/8" id heater hose.
 

Jbulach

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I took off one of the inflation valves on one of the wheels with a leak and the valve is female compression. The adapter from the wheel that it attaches too is also female. Is there a male adapter that is supposed to be there? Don't see how it could seal otherwise.
Are you working on the front axle or one of the rears? Also what part of Indiana are you from?
 

IanW

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Evansville. Rear axle. I just don't get how it's supposed to seal with two flares of the same shape. Example- a brake line. A flare like that trying to seal to another flare exactly the same. I wish I could post a picture. The threads aren't stripped and the rubber is fine.
 

Andyrv6av8r

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Evansville. Rear axle. I just don't get how it's supposed to seal with two flares of the same shape. Example- a brake line. A flare like that trying to seal to another flare exactly the same. I wish I could post a picture. The threads aren't stripped and the rubber is fine.
The slight flare on the tube is only to keep the nut from slipping off, not a sealing surface. Some tubes actually don't have any flare at all on the end and seal just fine. The seal is accomplished when you tighten up the nut onto the wheel valve nipple (male threads) and the rubber seal inside is compressed against the OD of the tube coming out of the hub. Make sense?
 

IanW

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It does. Thank you for clarifying that. Getting gear oil out of one of them also. Is there a place to get a seal kit? Sorry for all the questions. Been building vehicles for years but the CTIS system is very foreign to me. It appears like it is to most people.
 

Stellaevil

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Can you post up a picture of the banjo bolt you are talking about?
If the CTIS tire hose is not leaking and the tire bead is not leaking check these two places.
Remove the control port hose from the wheel valve and cover the port with your hand, no pressure should be building 2-minutes (if pressure is present the WV is problem) disassemble and clean inside parts.
There is an 'O ring between the two wheel halves that can leak and is crazy hard to find. You have to remove the wheel from the truck and soap the whole thing inside and out and the tire to make sure.

Remember: there is only pressure on the air seals and the control side "metal tube" when the CTIS is inflating or deflating so those areas of the system are not responsible for tires leaking down over time.
 
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brazengoat06

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ok so I have a m934a2 with 5 flashing lights the come on after normal air pressure is reached. the in cab unit will pressure check but not work. ive looked for leaks during the pressure check and can find none. Ive read through this but could use some additional thoughts. thanks
 

1 Patriot-of-many

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ok so I have a m934a2 with 5 flashing lights the come on after normal air pressure is reached. the in cab unit will pressure check but not work. ive looked for leaks during the pressure check and can find none. Ive read through this but could use some additional thoughts. thanks
Hold the bottom button down for a second or two. Should start airing up..
 
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