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twentyohtwo

Exhaust brake woes at 0 degrees

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Hey folks, This is my first winter with my Pacbrake. It had run flawlessly until ambient temps got down to around 10 degrees. Then it stopped working on my way home one night. The next morn. after I warmed the truck up for an extended period, it started working again. This cycle went on for a couple of days, then my 30 amp compressor fuse blew. I replaced the 30amp with a 20 amp.  ambient temps are now around 32 and she's back to working reliably.

 

My compressor is located by the passenger side battery as directed in the pacbrake instructions. I routed the air intake filter to the firewall behind my Bhaf. I have not yet remote mounted the actuator piston vent that pacbrake suggested to reduce intake of moisture . ( I had to mount my brake farther down the exhaust pipe because the 4" exhaust pipe didn't allow mounting the brake on the downturn behind the turbo.) 

 

I'm wondering if others have encountered this problem.  Thanks, Bret.

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Hmmm... Being compressed air always has a certain amount of moisture its going to freeze. I'm not sure what you could do to possibly filter off or separate the water before devices?

 

I'm reverse of you the Jacobs brake works on vacuum so there is no chance of water in the system since water boils in a vacuum.

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Hmmm... Being compressed air always has a certain amount of moisture its going to freeze. I'm not sure what you could do to possibly filter off or separate the water before devices?

 

I'm reverse of you the Jacobs brake works on vacuum so there is no chance of water in the system since water boils in a vacuum.

 

I'm gonna rock the boat cause I'm bored.

 

According to my calculations and the TSB that says you should have 10-20" Hg, that means a max of 9.8psi drop.  At 5000ft you are at 12.2psi, subtract 9.8 and you are at 2.4.  This is all absolute psi.  At 2.4psia, water boils around 130F.  At a more modest 2000ft, it boils at around 150F.  That is only with the max vacuum spec....  

 

In other words, I don't think its boiling.  I don't think the vacuum lines get that hot when the engine is only 180-200F and the vacuum lines are an insulator and not even sitting on the engine for the most part.  

 

I think vacuum lines are better since they obviously don't have as much air in them meaning less water as well, but I'm betting they would still freeze given the right circumstances.

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maybe plumb in a water separator after the compressor?

we built these into the old York AC compressors we turned into on board air. might be worth looking into its easy to do and cheep.

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I must have a different model of pacbrake. Mine runs on vacuum as well.... They make small water separators for use on like air compressors in shops and stuff. Might be worth looking into something like that because not only would it act as a seperator, but also a filter..

Edited by Ilikeoldfords

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Thanks for the input. I'll do a little research on water separation. In my experience water separation takes place after the air is compressed, downstream from the compressor. If I had a blockage at that point it seems that it would simply satisfy the pressure switch and shut off the compressor. However my compressor fuse blew. To me it seems that would be due to condensation created by the heat of compression and low ambient temps.  The system came with a cheap air intake sock and I located it in a dry area. Perhaps I can find a better prefilter , or maybe i"m missing something mechanically speaking.

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