Bought another 1078, might need help with this one.

[Smokinyoda]

This will be my ongoing help and thinking out loud thread.

Stumbled upon to good of a deal to pass up, scrap price for running truck. Might need some troubleshooting help getting it safely back on the road.

First thing I'm working on is brakes for obvious reasons. Front brakes work fine, rear spring brakes not working properly. When parking brake knob pulled only hear small hiss of air and brakes do not apply. If I bleed tanks down passenger side rear applies, but not drivers side. I thought since not much air released when applied that valve must be bad so replacement has been ordered, figured drivers side was just out of adjustment.

Then I started checking rear service brakes and discovered only passenger side works. I was expecting this since drivers side spring brake also wasn't working. Pulled drivers rear drum off to clean and inspect. Notice when brakes applied plunger does not move at all. I am somewhat new to air brakes but figured even if out of adjustment you would still see the plunger move a little when brake pedal applied. Tomorrow I will try to adjust.

Any comments/suggestions so far? Can out of adjustment brakes show no movement when applied or I am I looking at other failures?

 

[FloridaAKM]

There are quite a few threads here on the air brake systems of the LMTV's, so do a search for those threads for some informative reading & problem solving. Reading them would be much faster & to the point than trying to discuss it here.

 

[Suprman]

Is the front red gladhand blocked off to prevent air leak from draining the tanks?

 

[Smokinyoda]

Suprman

Is the front red gladhand blocked off to prevent air leak from draining the tanks?​

Thanks Will, but that's one of the first things I checked after reading about it being involved in so many problems on here.

There are quite a few threads here on the air brake systems of the LMTV's, so do a search for those threads for some informative reading & problem solving. Reading them would be much faster & to the point than trying to discuss it here.

I was wondering how long it would take for someone to say read the TMs or search is your friend! That's one of the reasons I don't post in here much anymore.

I always try to search first if I can't find my answer in the TMs. And yes there is a lot of good info in some of those brake threads, I just couldn't find the answer I was looking for.

 

[Awesomeness]

If the rear driver's spring brakes don't apply either, it seems like it's not an air problem. There is likely something mechanically keeping the brake from moving.

I always try to search first if I can't find my answer in the TMs. And yes there is a lot of good info in some of those brake threads, I just couldn't find the answer I was looking for.

The search on this site is pretty terrible, and if you don't know the exact/correct wording of what you want it's often easy to pass it by. People on this site, more than any other forums I've been on, also branch way off topic for the post title (e.g. brakes in a battery thread) and the nugget of info you want is buried in a dozen pages of banter, rebutal, theories, corrections, etc. It's why I started carefully reading through the posts I cared about, and writing down consolidated versions in my own document... I don't ever want to have to look it up again in the forums. To top it off, reading the TMs can be quite convoluted, and it will hide important little things in unexpected places (which I'm sure contributes to why many of these vehicles come from the Army with such poor maintenance in the first place).

I hope you figure out your brake problem.

 

[tennmogger]

Did you check the "bad" side to be sure the brake is not caged?

I agree completely, Awesomeness, that searching can take a l-o-n-g time to find an answer to a specific problem. In addition, many early threads about a subject have solutions suggested that are simply wrong. FMTV is especially that way because the span of released vehicles has been a short few years, compared to a Deuce, for example. Reading is great but folks shouldn't hesitate to ask a question. Long-term readers know the "latest answer" and can provide it. That's the only way to make use of the developing knowledge base on this great forum.

Bob

 

[Awesomeness]

Did you check the "bad" side to be sure the brake is not caged?

Good catch.

That's the only way to make use of the developing knowledge base on this great forum.

I think this statement is the heart of the matter. The definition of "forum" is a place to meet and discuss, and "knowledge base" is a curated location for information. Not really the same thing. That's why I started writing the "Common Problems and Fixes" document for myself (shared in my signature), to try to start extracting the knowledge base from the forum discussions. Many thousands of posts in many thousands of topics is too much to wade through.

 

[Smokinyoda]

Did you check the "bad" side to be sure the brake is not caged?

I agree completely, Awesomeness, that searching can take a l-o-n-g time to find an answer to a specific problem. In addition, many early threads about a subject have solutions suggested that are simply wrong. FMTV is especially that way because the span of released vehicles has been a short few years, compared to a Deuce, for example. Reading is great but folks shouldn't hesitate to ask a question. Long-term readers know the "latest answer" and can provide it. That's the only way to make use of the developing knowledge base on this great forum.

Bob

Yep I checked that before bringing it home. I have spent several hours playing with it today. the front can on rear drivers side is now working, was just out of adjustment. The rear drivers side back can is still not working. No matter how much I adjust it the plunger will not move when brakes applied. That leads me to believe the wedge is stuck forward, and brakes were adjusted to compensate. My next step is to cage the back can and pull the entire assemble off to check the wedge.

 

[CARMAN]

Just had that problem with my M923. Pulled the wedge and it was fine but the pistons were stuck out and brakes were adjusted way tooo far out. Was a quick fix.

 

[Suprman]

I had one before it would randomly loose spring brakes while driving. Very scary. The brake pads and chambers were all working properly. I replaced the treadle valve, inversion valve and the anti compounding valve and the issue went away. I believe it was the anti compounding valve sticking. The tube with fins air dryer gathers moisture and concentrates it in your brake system causing corrosion and buildup of gunk.

 

[Smokinyoda]

Think I might have found the problem!

 

[Awesomeness]

What is all that stuff in there?

 

[tennmogger]

Think I might have found the problem!

Yep, there's a strong clue there! Good going.

 

[Smokinyoda]

What is all that stuff in there?

Looks to be the remains of a broken spring. Now to try and find replacement parts for everything. So far I haven't been able to find part numbers for the guts of the cans in the TM, just the entire can assembly.

 

[Rmtaunton]

Probably easier to but a new one from napa that one is a mess


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[Andyrv6av8r]

Suprman to the rescue!

 

[Smokinyoda]

Probably easier to but a new one from napa that one is a mess


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Yeah your probably right. Checked Napas website and no results for part number from TM which is X24-3276J-10. Ill call tomorrow and see if a real person has better luck finding one.

 

[Suprman]

I have those. What year is the truck? 94-97 use one can and 98 up a different one.

 

[Smokinyoda]

I have those. What year is the truck? 94-97 use one can and 98 up a different one.

Its a 96, sending you a pm now.

 

[Smokinyoda]

OK I got all the brake issues sorted out. Luckily a guy nearby had a brand new axle, and he didn't need the brake parts for what he uses them for, so I got all 4 chambers and wedges cheaper than one would have cost me.

New problem involves a leaking tire. Truck came with 1 brand new tire and 3 equally used tires on the ground, and a brand new one on spare rack. So I pulled the new spare down, replacing it with a used one and put both new tires on front. And for several weeks it sat that way while I worked on rear of truck. No leaks anywhere. First time I drove it, next morning woke up to the new front tire flat (used to be spare tire). Aired it up, sat for several days with no leaks. Drove it again last night and this morning its flat.

So the tire itself is not leaking, when aired up manually from the valve core it wont leak down. But when driving it, some how the CTIS doesn't seal and it will leak down. But the old tire I took off didn't do it so I am confused, maybe the valve assembly on the wheel itself. I listened last night for a leak and couldn't hear anything. I will drive again soon and after parking go over everything with soapy water.

Anyone else seen anything like this? Where it only leaks after using CTIS, but will stay up indefinitely after airing up from valve core?