Air Lines Frozen

[hellpounder]

Newbie, 3rd week of owning an '86 M934A1. 15F in Indiana today, was 8F last night. Started the truck [added proportional amount of antigel, preheated the oil pan with a heater for a bit [still waiting on oil pan heating pad and block heater to show up] gave it a few squirts of ether on and off [since it doesn't have glow plugs] and it started well enough], but the air tanks read 0, and every 10-15 seconds I could hear the blowoff valve popping to let the air out, so I can tell the compressor is building up air, but it isn't making it to the tanks. I let it run about 2-3 minutes with the idle at probably about 1100, but there wasn't any change, and I didn't want to risk damaging anything, so I shut it off.

I read the TM, thought about doing the moisture release procedure, but the previous owner told me the air drier and air system was already serviced shortly before I got it, so I figured it wouldn't be necessary, but I guess I may have been wrong.

I tried searching the forum for info, but didn't have luck with the keywords I chose. I thought about setting a heat gun to about 200F and trying to thaw the components, then start the truck, build air, and try the TM bleeding procedure. I want to add air brake antifreeze, but not sure where the best spot would be. Any advice would be greatly appreciated. Right now this is my only functioning winter vehicle and I want to be prepared.

 

[hellpounder]

Tried again later in the day, the freeze must have thawed, I was able to build up pressure fine. I bled from the drainvalves according to the TM, but the valve for the wet tank doesn't seem to be doing anything, not sure if that's normal or not. The primary and secondary tank drainvalves had pressure, and a little from the spring brake tank, but none of them appeared to have moisture. I made sure to let the truck run and build up pressure to ensure it could expel thoroughly. I will take the dryer filter off tomorrow and inspect it.

 

[hellpounder]

Looks like the air dryer is a Haldex N-50011f. A line is disconnected. I'll try to see where it goes tomorrow.

 

[juanprado]

That wire is for the 24v heater on the dryer.
Not sure if I see a heater on yours?
Could be the dryer was serviced with out it.
Original is a haldex dq6015

 

[hellpounder]

That wire is for the 24v heater on the dryer.
Not sure if I see a heater on yours?
Could be the dryer was serviced with out it.
Original is a haldex dq6015

I'm guessing they just didn't come with hookups for the heater. I found another video of a guy servicing one of these on a 900 series and his heater plug was disconnected as well. If I'm understanding correctly, the heater is mostly for the blowoff, but my blowoff was working, I just wasn't getting air to the tanks. I thought about adding air brake antifreeze, but further reading, it could wreak havoc on my ABS, air dryer, etc.

 

[juanprado]

It has been a while since I rebuilt mine as the piston was sticking. I remember changing the heater but do think mine did have the heater installed originally.

The first models had an alcohol bottle but it was deleted when they were upgraded with the abs mwo. I think the dryer and heater do not like the antifreeze. Mine still had the bottle on the driver's side of the engine and took me a while to learn what is was as very few pics of the early set up are out there. Seems all trucks were required to be upgraded to abs because of wrecks , rollovers, and fatalities.

Common problem is the check valves on the lines going bad. Follow the line from the wet tank and disconnect the valve and check it out. Common civy haldex part, nothing special.

I don't deal with your weather here in New Orleans so others would need to chime in on cold weather work arounds.

 

[hellpounder]

It has been a while since I rebuilt mine as the piston was sticking. I remember changing the heater but do think mine did have the heater installed originally.

The first models had an alcohol bottle but it was deleted when they were upgraded with the abs mwo. I think the dryer and heater do not like the antifreeze. Mine still had the bottle on the driver's side of the engine and took me a while to learn what is was as very few pics of the early set up are out there. Seems all trucks were required to be upgraded to abs because of wrecks , rollovers, and fatalities.

Common problem is the check valves on the lines going bad. Follow the line from the wet tank and disconnect the valve and check it out. Common civy haldex part, nothing special.

I don't deal with your weather here in New Orleans so others would need to chime in on cold weather work arounds.

Yeah, I'm gonna hold off on antifreeze. I've got a dryer and ABS. I'll try to get to that tomorrow. Thanks a bunch.

 

[hellpounder]

Got the lines thawed the other day, cracked the 3rd drainvalve for the wet tank, and a ton of liquid burst out. I wasn't quite certain where the exit point on the drainvalves were, but after the clog busted, I see that it is in the center, and that all of the valves were clogged.




I dug at the clogs with an ice pick and got them freed, then restarted the bleed procedure. Main, secondary and spring brake tanks didn't have much moisture, but the wet tank I ended up bleeding for 20 minutes, it kept spraying mist and an occasional bit of debris, but it seems pretty clear now as well.

Since all that is functional now, I'm going to make sure it gets bled each day I drive it.

 

[silverstate55]

I know 12-volt versions are available but unsure about 24-volt versions….I have installed automatic tank drains with heating elements in trucks before, simply run one power wire and the other is Ground, it helps keep the drain valves from freezing up. I want to say that they were Bendix items but can’t be 100% sure.

 

[hellpounder]

I know 12-volt versions are available but unsure about 24-volt versions….I have installed automatic tank drains with heating elements in trucks before, simply run one power wire and the other is Ground, it helps keep the drain valves from freezing up. I want to say that they were Bendix items but can’t be 100% sure.

Thanks, I'll do some research. I've thought about getting auto drains. I can purchase a 12v stepdown for about $15, so that's not a problem, I did that for the camera system.

Sounds like it's pretty simple. Do they just replace the factory drainvalves? Or are they positioned in-line behind them?

 

[Guyfang]

Your "Clogs" look like the work of Mud Daubers. They are a pest to all outdoors equipment.

 

[silverstate55]

Thanks, I'll do some research. I've thought about getting auto drains. I can purchase a 12v stepdown for about $15, so that's not a problem, I did that for the camera system.

Sounds like it's pretty simple. Do they just replace the factory drainvalves? Or are they positioned in-line behind them?

The auto drains replace the stock drain valves…they have multiple ports so you can mount to side or bottom of air tanks. Plugs are generally included to block off unused ports. Pretty straightforward.

 

[hellpounder]

The auto drains replace the stock drain valves…they have multiple ports so you can mount to side or bottom of air tanks. Plugs are generally included to block off unused ports. Pretty straightforward.

Sweet. I'll try to get some after I get a few more things done. Thanks a bunch.

 

[hellpounder]

Got down to the negatives this weekend, with a high of 4F. Some winter diesel with antigel, a block heater from Army 6x6 LLC, and a few shots of ether started it up well enough, the purge valve kept popping off, lines froze again, but only for a very short period of time, they unfroze while I was troubleshooting, with the exception of the lines that go to the dash controls. After trying to trace lines, using various heaters in spots, letting the truck run and continue to warm up, nothing worked. I resorted to ChatGPT, which has been very spotty about these trucks, but it pointed me towards a Pressure Protection Valve [PPV] that, it claimed, sat under the cab, and showed me a picture. I never found it anywhere near where it told me to look, but I remembered seeing one attached to the wet tank, so I pointed a heat gun at it for about a minute, then I heard the clunk of the front axle piston engaging - checked the dash, and the freeze cleared. Got to drive around in all the snow for the first time, after finally fixing the front axle [which I spoke about here https://www.steelsoldiers.com/threads/front-axle-not-engaging.225509/]



I am keeping a Ryobi cordless heat gun in the truck to be able to thaw quickly, which is working out. The drainvalves all seem clean when I drain them, but there could be some residual moisture in the valve, or it could be gunked. I'll pick up another one from Army 6x6 for $50 soon to swap out and keep this one as a spare. The next thing I want to do, aside from auto drainvalves, is figure out the wiring for the purge valve heater on the air dryer, since there doesn't appear to be any truck-side wiring for it. Any recommendations on that would be appreciated.