CTIS just stopped working.

[dc239]

Hello Everyone,

I recently purchased an M109 shop van. Everything was running fine. Drove it about 260 miles before the CTIS malfunctioned. Went under the vehicle and checked all the hoses and connections. Made sure they were tight. But I still couldn't get my tires to fill above 20 PSI

I'm watching the CTIS indicator, which I have set to Highway (45psi). I hear the system click on underneath the truck. At this point the CTIS reads Manifold pressure 0. It runs and fills up to about 20-21 and then I just hear a loud hiss from under the truck. The CTIS just repeats this process and my tires never fill.

So I went under the truck to see where that air leak could be and it appears to be from here (see attached picture). As you can see, some oil has came out as well.

Can someone tell me why air is coming from these valves and how to fix it?

Also, is there a TM specifically for the CTIS? I may have missed it but I didn't see much about it in the TM referenced when searching for it on this site. All the generic deuce TM had was a description of the system and how to use it.

 

[dc239]

I forgot to mention that I am able to fill my tires manually and they do hold air. So I don't think there's anything wrong with my tires.

 

[hklvette]

If its blowing oil out of the breather (the silver part pictured), you have a dead inner hub-seal.

 

[dc239]

If its blowing oil out of the breather (the silver part pictured), you have a dead inner hub-seal.

The air and oil is coming from here. Is this the breather? So having a dead inner hub seal only effects my CTIS? The tires hold air when filled manually...so I'm just assuming.

 

[hklvette]

The air and oil is coming from here. Is this the breather?

Yes.

So having a dead inner hub seal only effects my CTIS?

I think so but the hub seal may work in both directions, that is both keeping air out of the axle and oil out of the CTIS bits. Someone with more knowledge about how the M35A3's axles are assembled will have to chime in here. The reason you can manually inflate the tires is because when the system is depressurized, the wheel valves isolate their wheel from the rest of the system.

 

[dc239]

I don't have the finances, tools, or even the workspace to change these seals. Do you think the truck is safe to drive long distances if I disconnect the CTIS and just manually inflate my tires? I need to drive about 1000 miles.

 

[welldigger]

Yes.

The seals are just an o ring that goes in behind the bearing. If I were you I would permanently disconnect the ctis. I'd even go as far as removing the wheel valves and just have regular valve stems. It will save you a lot of money and aggravation.

 

[hklvette]

Yes.

The seals are just an o ring that goes in behind the bearing. If I were you I would permanently disconnect the ctis. I'd even go as far as removing the wheel valves and just have regular valve stems. It will save you a lot of money and aggravation.

As much as I hate to admit it, this is the most sound advice. If you don't have a use for the CTIS on a regular basis, it isn't worth trying to maintain the system.

 

[dc239]

As much as I hate to admit it, this is the most sound advice. If you don't have a use for the CTIS on a regular basis, it isn't worth trying to maintain the system.

This is what I had planned on doing. I just wanted the CTIS just to have it. But I can live without it. At least now I'll feel better about my 1000 mile drive West.

 

[1 Patriot-of-many]

Just turn the CTIS off. I have a bad seal on one of my axles too, I still get enough air at high rpms to inflate the tires, but I'm getting the air out the breather too. Probably the outer seal, as that's the direction the air has to go to enter the axle. If it were the rear seal it would be coming out behind the hub. I just have mine turned off and manually air the tires up. I run them at 60psi anyway, think the CTIS airs them to 45. Bear in mind, if air is getting past the seal, axle oil probably is too. It washes the grease out of the bearings, last hubs I pulled were completely clean of grease. These bearings are what $700 a piece? It's probably in your best interest to pull the hubs on the axle that's venting air and fix the problem.. I know kettle calling pot here.

 

[MtnSnow]

CTIS depending on which "firmware" the ECU is programmed with is supposed to inflate to 60 psi in Hwy mode or 70 psi Hwy mode in the 923,925 models (A2 versions) and like 80 or 90 psi in the 936 model (these are for the A2 versions) Mine has the older firmware and stops at 60 psi

 

[1 Patriot-of-many]

CTIS depending on which "firmware" the ECU is programmed with is supposed to inflate to 60 psi in Hwy mode or 70 psi Hwy mode in the 923,925 models (A2 versions) and like 80 or 90 psi in the 936 model (these are for the A2 versions) Mine has the older firmware and stops at 60 psi

This is the deuce forum

 

[MtnSnow]

Doh...Sorry missed that little tidbit

 

[1 Patriot-of-many]

Don't worry, i think the simpsons father was patterned after me.

 

[glcaines]

If you're driving on a 1,000 mile trip, you don't want to be running 45 PSI anyway. Even if the CTIS functions, turn it off and inflate the tires to 60 PSI. The truck will run a lot smoother and your tire and fuel mileage will increase. Don't run more than 60 PSI, though, as the wheels are red-lined at 60 PSI. I run 60 pSI full-time and my CTIS works fine.

 

[rtk]

On my A3 , I removed the CTIS bearings and seals and replaced them with A2 bearings and seals . That system was and is a NIGHTMARE ! I will bet you have gear oil in some of your air valves , you need to fix that ASAP as the gear oil will wash out the grease in the wheel bearings . It is easier to replace the bearings with the A2 stuff then it is to repair the CTIS . Wait till you price some of the bearings and seals for the CTIS setup , better be sitting down !!!! I have down the change over and can guide you through it PM me if you need to . You will also need a set of front spindles as they machined off the seal area to fit the CTIS inner bearing . I also have the PARTS from the CTIS SYSTEM that I removed if anybody is in need . Bob k

 

[dc239]

Tires filled and CTIS disabled. Leaving today for South Dakota. Have an 890 mile drive according to google maps. If you see a deuce on the side of the road in WI or MN, its probably me

 

[1 Patriot-of-many]

Good luck!

 

[dc239]

Doing well. About 360 miles left and Ill be in the Black Hills. This is my 2nd day of driving. This morning I filled the tires up to 50ish. Checked them at a rest stop because I thought I had a flat. And with the exception of my back left tire (55psi) the tires were reading 60 or just under it. Tires were fine, the road is just conplete garbage. There was a crack like every 15 feet. Rattled my brain for like 150 miles.

 

[1 Patriot-of-many]

I 90? In MN always a treat.