Tire won't take air M35A3

[DownRange762]

My apologies to those of you seasoned enough to have held the TM while Moses changed the wheel on the first tactical chariot, but I haven't seen this problem before.

Recently acquired M35A3 on which the LA National Guard had disabled the CTIS. While checking tire pressures before getting on the road, one of the tires didn't read on either of two different handheld pressure gauges. Gauges work fine on the other six tires on the truck so it's not a gauge problem. The tire in question however based on the "thump method" appears to have some air in it but is it 10 pounds or 110, I have no idea.

Ok, fine, maybe a little crud in the valve stem so I removed the valve core. Looked fine, no corrosion and it moved by finger pressure as expected. Reinstalled, still no air reading no will the tire accept air from my compressor. Exchanged original valve core with two different new cores, still no reading, still no inflation, no escaping air anywhere.

Even without any valve core in the valve stem there is no escaping air, nor will the gauge read, no will it accept air. Working from under the truck and using the second valve stem that shares a common "T" block (attached to the wheel) with the first, same situation, no inflation.

Same air compressor (portable, not the truck's) inflated all other tires as expected.

Ran a pipe cleaner inside the valve stem but it came out reasonably clean and went in as far as the "T" block but no further, likely due to the 90 degree turn required to go inside the wheel.

Any thoughts before I have to pull the tire off the truck and break it down? Corrosion/blockage in the "T" fitting or some bizzare CTIS disablement process that wasn't used on the other six tires/wheels?

 

[319]

What "T" fitting are you referring to? I don't see one on the wheel. Maybe you can post a photo.
If the tire is completely flat, it will take a while to read on your gage while inflating. If that's not the issue, then there is an in-line filter, #36 on the attached illustration, that could be clogged, or possibly your hub seal is leaking and oil is getting into the lines and clogging the CTIS valve.

Remove the CTIS parts and thoroughly clean them before breaking the tire down.

And I don't think Moses actually changed the wheel, he supervised.

 

[DownRange762]

Thanks for the reponse and diagram. I"ll see if I can turn up an image of what I'm calling the "T" fitting.

The LA National Guard disabled the system and removed many of the CTIS components. There is no CTIS valve on my truck wheels now. I haven't removed the wheel from the truck yet but from what I can see, I've got a regular tire stem valve on the outside of the wheel that is easy to get to. It in turn is connected to a "T" fitting which is attached to the inner surface of the wheel. Coming out the other side of the "T" is another valve stem.

On the back side of the wheel there is a flexible line running from one fitting about 8" to another fitting, I'm guessing as a quick fix rather than finding appropriate plugs after some of the CTIS components were removed.

As for the gauge reading, I agree, it would take some time to move enough air into a completely deflated tire for the gauge to read. My concern however is that with my compressor regulator set to 60 psi or even 120 psi, no air flows from the compressor into the tire so I"m still thinking there is a blockage but then there are very few components left to be at fault.

 

[319]

Thanks for the reponse and diagram. I"ll see if I can turn up an image of what I'm calling the "T" fitting.

The LA National Guard disabled the system and removed many of the CTIS components. There is no CTIS valve on my truck wheels now. I haven't removed the wheel from the truck yet but from what I can see, I've got a regular tire stem valve on the outside of the wheel that is easy to get to. It in turn is connected to a "T" fitting which is attached to the inner surface of the wheel. Coming out the other side of the "T" is another valve stem.

On the back side of the wheel there is a flexible line running from one fitting about 8" to another fitting, I'm guessing as a quick fix rather than finding appropriate plugs after some of the CTIS components were removed.

As for the gauge reading, I agree, it would take some time to move enough air into a completely deflated tire for the gauge to read. My concern however is that with my compressor regulator set to 60 psi or even 120 psi, no air flows from the compressor into the tire so I"m still thinking there is a blockage but then there are very few components left to be at fault.

Sounds like an interesting set up on the valves. Please post a photo when you can.
I agree with you on the blockage then. You'll have to bust that tire down to fix it, and when you do, replace the o-ring.

 

[Recovry4x4]

Checking and adding air requires 2 things. With many tire chucks the little tit inside the chick needs to be pushed back in to release the flow of air. I have encountered valve stems where the core is too deep and cannot depress that tit to allow the flow of air. With that said, perhaps the unit that had the truck grew weary of trying to keep the tire inflated and filled it with foam.

Gonna take some checking.

 

[DownRange762]

Here are a couple of pics to illustrate what I've got.


This first one is a view from under the truck looking at the backside of the wheel. Note the second valve stem facing to the inside of the truck. The tube going through the wheel goes to a conventional (non CTIS) valve stem on the outboard side of the wheel. Neither valve stem on this wheel allows air to pass in either direction.

The middle pic is from my spare showing what the TMs show...just a right angle "turret valve" with one end going outboard of the wheel to a conventional valve stem and the other end entering the wheel. Works fine, air in or air out.

The last picture is a view of the outside of the wheel in question showing that CTIS components have been removed. Looks the same as the other six wheels on the truck.

Have tried three different air chucks now to inflate or deflate without success so I'm down to either there is corrosion/gunk in that "T" fitting or some bright bulb at the Guard foamed this tire. Any other ideas?

Lastly, for safety's sake let's assume there is pressure in this tire with no way to deflate using the valve stems. Any process to begin disassembly in a controled manner allowing air to escape without injury?

 

[shovelheadmike]

Mine came from the SC National Guard. They disabled the CTIS, and pumped red RTV into everything on the front passenger tire. That took a while to clean out. Same pressure measurment problem you have.

 

[DownRange762]

When you say they pumped red RTV into everything you mean what they left on the wheel after pulling the CTIS off, or did they try and fill the tire with it too?

If that is what happened in this case, any hints on getting it out? How did you start the dismount of the tire with air still in it?

 

[319]

Your spare tire setup (elbow with 3/8" pipe) is correct, the others are modifications. Not sure of the safety aspect of this but you might try loosening the nuts holding the wheel halves together a little bit at a time, letting the air if any, escape slowly.

 

[shovelheadmike]

I just started taking apart the CTIS on that wheel. Could not get the air out until I poked a wielding rod into the 3/8 ntp nipple.

 

[DownRange762]

It's the only wheel on the truck with two valve stems but I doubt that is really the problem. I'm guessing either there is a clog at the "T" block since neither valve stem works, or this tire has been foam filled.

Guess either way, slowly unbolting the rim bolts to control the air release is the only way to go.

 

[shovelheadmike]

I started at the valve stem and worked my way in from there. Was too leary of messing with any bolts/nuts. Seen too many things get launched that way. Very good entertainment value if you can watch someone else do it from a safe distance!

 

[DownRange762]

Think I'll have to start by loosening the wheel havles since taking the stems out of both valve bodies doesn't move any air which tells me the problem is "upstream" being either in the "T" block itself or even more gunk inside the wheel. But thanks for the tip about trying to break it free with a rod.

 

[319]

You'll need a 1-1/8" deepwell for those wheel nuts.
Let us know what you find.
With photos of course!!

 

[wreckerman893]

Are you sure the air is not escaping through the O ring that seals the two halves of the rim together.

I had the same issue with one of the wheels on my M927.....it would leak down over a few days but I could air it back up. You could not hear the air escaping but once the tire shop took it off the truck and aired it up the leak was visible when they put soapy water on it.

Just my input for what it's worth.

 

[DownRange762]

Good point and no, I'm not positive that isn't happening. I can't hear any air moving through the hose (compressor not running of course so I can hear). However in my case it doesn't take any air so I can't even get to an O ring leak stage yet. But thanks for the input and once I get this thing taken apart I'll double check the O ring condition.

 

[DownRange762]

Mystery solved

If I could view the site from my home computer I'd have added photos right now but I'll do that Monday.

In short, apparently during its service with the Guard, this M35A3 had the tires partially deflated enough to allow the tire to unseal from the rim while the vehicle was in mud/water. Enough mud/water in fact to fill more than half the tire. Then the truck was parked with the tire rotated so the valve assembly was at the bottom of the rotation and the valve body (not the stems) filled with mud.

Once the tire/wheel was broken down gallons of water came out along with a lot of mud. Will clean it all up, sandblast the rim and put it all back together.

Of course now the other five wheels are suspect so the game continues.

 

[DownRange762]

A look inside the wheel

Some of the accumlated mud/rust/crud has been knocked out of the valve fitting but you can see the effect of water being in the wheel for an extended period. No wonder the valve was blocked.