CTIS issue

[Flea]

Ok 5-tonners...

1991 M923A2. Factory CTIS was giving the 5-light blink, so I did the full manual controller conversion:

https://www.steelsoldiers.com/showthread.php?161829-Manual-CTIS-control-how-to

Once I got it installed, I ran air through it. The dump valves opened and tires were deflating properly. When I went to inflate, there was a very high pitch squeal coming from the rear duals area, but no air from the dump valves. The compressor kicked in on the motor, so air was moving somewhere. Air pressure in the tires, however, dropped in all of them to about 20 lbs. Regulator was set much higher.

My question is: when the CTIS is working and inflating, if one tire is lower than the rest, will the system equalize before inflating? Air is going somewhere, but I can't find any leaks. And second, where should I start to find the source of the squeal when it is inflating?

I have confirmed that there are no schrader valves that have been added to the wheels.

 

[74M35A2]

The CTIS is a single channel system. It has no idea how many tires are connected to it.

 

[Andyrv6av8r]

Bad hub seals tend to squeal.

" When I went to inflate, there was a very high pitch squeal coming from the rear duals area, but no air from the dump valves " Air is not supposed to come from the dump valves when inflating.

 

[KRedd]

https://www.steelsoldiers.com/showthread.php?154172-Dana-CTIS-Troubleshooting-Guide-(M900-series)

 

[KRedd]

Sorry, did not realize the link was the same. Also on Steel Soldiers is the newest TM's for the M900 series. Check TM9-2320-272-23-1, work package WP-0142 and see if this helps.

 

[M35A2-AZ]

Bad hub seals tend to squeal.

" When I went to inflate, there was a very high pitch squeal coming from the rear duals area, but no air from the dump valves " Air is not supposed to come from the dump valves when inflating.

That is my guess as well.

 

[Flea]

Ok, the squeal is undoubtedly a hub seal. I am going to try to block off the one wheel and see if that will get the other 5 wheels going.

 

[Flea]

Just as an update, I blocked off the line going to the wheel with the bad hub seal. The system pressurized all five remaining wheels to 50 psi in a matter of minutes! All appears back to normal
I may re-install the computerized controller to see if that fixed the 5-light blink, too.

 

[TexasRam]

What method did you use to block off the line to the wheel with a bad hub seal? I'm encountering the same issue.

 

[Flea]

I just used a small piece of thick rubber that I cut a plug from using abhole saw. Cracked the air line going to the problem wheel, and put the plug between the fittings. Seems to work just fine.

The plug needs to be 1" in diameter.

 

[TexasRam]

Thanks ill give it a try.

 

[Jbulach]

I just used a small piece of thick rubber that I cut a plug from using abhole saw. Cracked the air line going to the problem wheel, and put the plug between the fittings. Seems to work just fine.

The plug needs to be 1" in diameter.

Interesting... any chance you can post a picture of what fitting you broke into?

 

[TexasRam]

Bad hub seals tend to squeal.

" When I went to inflate, there was a very high pitch squeal coming from the rear duals area, but no air from the dump valves " Air is not supposed to come from the dump valves when inflating.

What would be the cause of air to come out the dump valves when the system is airing up the tires? I have a couple tires that slowly lose air after a few days sitting and when the CTIS begins airing them back up to Highway setting air comes out the dump valves. But it is not dumping at the full air flow rate like when airing down to a XC, Sand or Emergency . After about 30 seconds the rate of dumping begins to taper off until its no longer coming out at all and the tires air up to Highway. Any idea what is happening or causing this?

 

[Andyrv6av8r]

What would be the cause of air to come out the dump valves when the system is airing up the tires? I have a couple tires that slowly lose air after a few days sitting and when the CTIS begins airing them back up to Highway setting air comes out the dump valves. But it is not dumping at the full air flow rate like when airing down to a XC, Sand or Emergency . After about 30 seconds the rate of dumping begins to taper off until its no longer coming out at all and the tires air up to Highway. Any idea what is happening or causing this?

My guess is a bad wheel valve. I had the same issue once. It ended up being a bad wheel valve. Trace which dump valve it is then you have it narrowed down to two wheel valves.

 

[TexasRam]

Thanks for the tip! I'll look into the wheel valves.