CTIS problems and gear oil everywhere.

[capnkirk]

Well, the CTIS on my M923A2 has been intermittent since I got the truck. Seemed like it was working fairly well today on the test drive. It would go from solid Hwy to flashing highway over a few minutes. All of a sudden, I get 5 flashing lights. I'm thinking now would be a good time to check for leaks. I unplug the controller, plug it in and jump out to listen for leaks. As I get to the back of the truck, I notice there is oil ALL OVER everything near and above the rear axle. I don't mean it's dripping. It looks like someone dropped a grenade in a gallon jug of gear oil. No soap or windex needed here! Sounds like wheel seals might have a bit of a leak.

So, to fix or not to fix? If I invest the time, can I expect this to function for a few thousand miles or am I wasting time?

I've been reading the TM CTIS sections. I understand a lot of how it works but it I need a work package with a flow chart that either ends with "SCREW IT. Disconnect it and tell your supervisor it's AFU. or YEAH, try to fix it. It might last (x) days. "

 

[Suprman]

You have a bad ctis axle seal. 15 dollar part but you have to pull the axle to fix it. Disable the system.

 

[capnkirk]

Was afraid that was the answer. Shouldn't I fix the seal anyway? It keeps the oil in the axle too right?

 

[stv2258pho]

May I ask where the oil is leaking? You may have a bad seal on the CTIS at the hub that allowed the hub to be pressurized from the CTIS system. It's happened to me in the past. After replacing the seal I put Lucas hub oil in there and it helps with the sealing issues as well after you get new seals in there. Not a bad job really. A few hours to do it right. I always feel the hardest part is pulling the darn wheel/tire off because I'm a sissy and they are heavy for me

 

[capnkirk]

It was hard to tell. Kinda like finding a needle in a hay stack. Oil sprayed under the cargo bed on both sides to the point where it was dripping.

 

[stv2258pho]

You can pull that axle shaft in minutes sir. Like I said the hardest part is pulling off the tire

 

[capnkirk]

Pulling wheels and tires shouldn't be too big of a deal this spring. I've got equipment but it's friggin cold now!

 

[capnkirk]

The tire should come off easy. Everything is pretty well lubed up now!

 

[stv2258pho]

The CTIS seal is super simple to fix. The hub input seal is easy as well the output seal on the hub is a bit more involved however can be done by most backyard mechanics with a decent tool box.

 

[stv2258pho]

I just hate pulling tires I guess cause they weigh more than I do boy I can't wait to try to pull my tires off my deuce NOT

 

[stv2258pho]

You said both sides of the truck are mess hmmm. Can I ask we're you out spinning those tires in the ice snow or mud recently?

 

[capnkirk]

Actually no. Drove to the end of mile section and back. Then drove out in field and back to shop. Tested brakes a few times. Wasn't crazy with it. Never threw any mud.

 

[stv2258pho]

The only reason I asked is that is seems odd to have two failing CTIS seals at the same moment however spinning those tires while out for a day of fun can ruin those hub output seals.

 

[capnkirk]

I would normally agree with you. If someone brought the truck back to me with 2 broken parts, I'd blame the driver! I think they've been leaking for a while. I had blinking highway light for a long time after picking up truck and the 5 blinking lights. Fixed
Some obvious leaks and seemed like it was going to come to life until today. Bought some inner hub seals. NSN 5330-01-271-9410. Should I replace more stuff while I have it apart?

 

[stv2258pho]

I would start there. I believe once you pull it apart you will find the culprit that is spitting under there. I have an Hummer that is always keeping me on my toes with the darn CTIS but I refuse to give it up because people get so interested at stop lights when they see the CTIS guards and it would be ashame to have to say sorry it's disconnected. So I will keep mine. Plus once I had to roll through 4 feet of water with a pretty strong current and airing down was the only thing that kept me from be sucked into the drink. I don't recommend you even cross water water in a real situation against the fire police warning. It is dangerous and I could have been arrested or worse. Good luck with that leak and remember don't look at the entire job. Turn one bolt at a time and it a lot more fun with a friend and a beer

 

[mcmullag]

just an idea...axle oil could be coming out of that top rear seal behind that thing that spins around where you bolt on a driveshaft. maybe the axle is getting pressurized somehow like somebody mentioned and/or the pressure relief valve is stopped up or not working and the oil is coming past this seal.

 

[73m819]

just an idea...axle oil could be coming out of that top rear seal behind that thing that spins around where you bolt on a driveshaft. maybe the axle is getting pressurized somehow like somebody mentioned and/or the pressure relief valve is stopped up or not working and the oil is coming past this seal.

Good call, this will throw oil every where, read though the whole thread looking for this suggestion, you beat me to posting it.

 

[Jeepsinker]

Make sure the driveshaft flange nut hasn't backed off allowing the flange to ride forward and off of the seal. It should have a cotter pin in it.

 

[capnkirk]

Thanks mcmullag and jeepsinker. I will check this after the polar vortex dissipates. It was very hard not to take the truck out in the snow!

 

[capnkirk]

Well. Leak located. (Sort of). Oil mist coming from the output coupling on the rear diff. Guess I get to figure out which hub seal is AFU. Found out my impact gun doesn't have the balls to remove a 1 1/2" lug nut tightened by probably the strongest Soldier B ever to walk the earth. (Yep, I'm turning it the right way.) FYI. PRO TIP for anyone troubleshooting air issues. With the engine and compressor running, it's too loud to find any air leaks. Make up a male to male air fitting to plug into your glad hand and hook up to your air compressor. All the air you'll ever need for CTIS and more and no running engine.