help with air system

Discussion in 'Trucks [ Eighteen Wheelers ]' started by gunner76, Aug 3, 2011.

  1. gunner76

    gunner76 Medium Load Member

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    I used a reman dryer and it's a AD9. I have a C15 acert in the truck and I know I got the right dryer.
     
  2. gunner76

    gunner76 Medium Load Member

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    I stopped by the dealer yesterday in between loads and had them look at it again. I unhooked the the supply line that goes from the compressor to the dryer and I only got a small amount of air to leak out so I was told that meant the check valve in the dryer was working.

    I've talked to 7 different mechanics at 4 different dealers plus you guys on here and everyone says that I've checked everything there is to check. I did talk to a friend of mine who said he had the same problem with one of his trucks and after doing everything I've done he went ahead and replaced the compressor and that solved the problem. I asked my mechanic about that and he said that he did notice that the compressor seemed to pump a little slow and maybe it isn't building enough pressure quick enough to make the system work. So I bought a new compressor and a guy is going to help me put it on this afternoon and see what happens.

    I don't know what else to do, I've either checked or replaced everything else in the system. Some things I've even double checked.



    ETA: I changed the compressor yesterday(very easy job on the 9900ix/C15 combo)and even though the new compressor pumps alot faster and is quieter it didn't fix the problem. I'm at my wits end with this thing so I called my mechanic up and said I'm bringing it up and do whatever it takes to make it right. I drove the entire 40mile trip to the dealer with the compressor trying to fill the tanks but the air was purging out the bottom of the dryer. I was a couple of miles from the dealer and had to stop at a light and that was enought to get the air down far enough to trigger the low air warning light. I still had four more lights to go through and I thought "this is going to be fun", I got close to the next light and started slowing down to try to keep from stopping and low and behold the system let the compressor fill the tanks.
     
    Last edited: Aug 6, 2011
  3. Heavyd

    Heavyd Road Train Member

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    Some how higher engine rpm is causing the purge valve to stay open. The purge valve stays open due to air pressure in the signal line from the governor to the air dryer. Some how air pressure is getting into the signal line with higher engine rpms. There is still something there with the compressor and governor. I know you have replaced everything. I would love to see this!
     
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  4. Heavyd

    Heavyd Road Train Member

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    If you pull off the signal line at the dryer then there is nothing to hold the purge valve open and no air leaking out the bottom. There should be no air in the signal line until the system has reached "cut out" pressure, around 120 psi. If you remove that line with the system below 80 psi and there is air something is wrong, or when you rev the engine there is air something is wrong. The next part would be the governor.
     
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  5. The Admiral

    The Admiral Heavy Load Member

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    How about maybe the reman is no good,it happens.
     
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  6. gunner76

    gunner76 Medium Load Member

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    this is what I'm trying to get my dealer to check. But since they already put a new purge valve in the reman and the check valve in the dryer that is behind the hot line from the compressor works they keep saying that there is nothing else that should be wrong with the dryer.

    It really ticks me off, I've thrown more parts into this thing trying to figure it out than I needed to and they won't even pull the airdryer off and try a different one. If the new one doesn't make a difference after one or two compressor cycles they could always pull it back off and keep it to put on someone elses truck since it is still basically new.

    I talked to a guy that said maybe there is a bad check valve in either the airtanks or between the tanks and the back of the dryer. I'm going to call my mechanic on Mon morning and see what they think about that idea.
     
  7. gunner76

    gunner76 Medium Load Member

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    The purge valve has also stayed open at lower rpm's also. The other day I started the truck up and while it was still at slow idle the compressor tried to fill the tanks and the purge valve just spit the air out. I let the truck run for 4min at speeds ranging from low idle to 1300 rpm's trying to get the system to work right. I then shut the truck off and restarted it about 15min later, at which time the compressor strted filling the tanks right away. I had already made arrangments with my dad to use his truck to finish my load and he would take mine back home and he said on his way home the compressor would start in around 100psi and would spit air out the purge valve until the air tanks would get down to 90 psi then the valve would close and allow the tanks to be filled.
     
  8. Heavyd

    Heavyd Road Train Member

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    The only thing that really hasn't be looked at yet, this is a long shot, but check that little spacer block between the governor and compressor. Maybe it is so plugged up that the compressor can't unload properly. I also wonder if the inside of the flex hose between the copper pipe and air dryer is coming apart internally and debris is getting caught in the purge valve holding it open?
     
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  9. gunner76

    gunner76 Medium Load Member

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    The spacer is fine, I looked at it before I installed it to the new compressor. The braided airline to the dryer is something I'll have to check.

    I'll call my mechanic in the morning and tell him to check that along with any check valves that might be behind the airdryer.

    A friend of mine says it's probably a $10 part that is causing all the trouble. He's probably right.
     
  10. Kansas

    Kansas Road Train Member

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    Find out where that air is escaping to. Isnt there a check valve between the air compressor and the reservoir tank?

    The fittings between the compressor and the tanks love to fail. Dont overlook it. On some trucks they can be really hard to get at. On mine, you gotta drop the #### drive shaft.

    Seems like at least once a week a truck with this very problem ends up parking to me in the middle of the night. Pstttttttt tsssst tsssst tssssst tsssssst tssssst sounds like a rattle snake with turrets syndrome.
     
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