| Author | Message | ||
| philshannon (198.81.17.162) Rating: |
Hey guys, problem of the day: The air compressor on My 4104 kicks in every 6 minutes going down the road. Asside from a few small air leaks that I have found using soapy water, I have yet to find the big one. I have pressurized the system and listened and sprayed for leaks around the whole bus including what can be reached with soapy spray around the air beams, air bags and air brakes. So far the only leaks that I have seen have been engine hoses and the only one I can hear is the air pressure regulator for the gradustat. I have replaced all the leaking air hoses at the engine with new ones. I have noticed that my air pressure regulator for my gradustat for the cabin A/C is leaking quite a bit out the bleed hole. According to Da Book, its always supposed to leak. How much? It does not say. Additionally, I've noticed that my magnetic shuttoff valve (fuel rack)has a small leak at the base. I will get that replaced as soon as I can find one. So heres my questions: 1. Where is my leak? 2. If the air pressure regulator is supposed to bleed all of the time, then how can the air pressure in the bus maintain pressure for days or weeks or months? I thought that was the idea! 3. Am I supposed to be able to maintain air pressure for days, weeks or Months? 4. Down the highway, how often would you expect the air compressor to kick in? 5. The air pressure bleeds off on my bus in 30 minutes, what efect is this having on my fuel rack? Doesn't it need air pressure to keep tha rack pivoted to the off position? 6. Would this condition lead to excess fuel in the cylinders and cause a smokey start up? I know its a barrage of questions, but if someone such as FF could answer them it would help me out with my on-going education on the 4104. Best, Phil Shannon PD4104-3832 | ||
| rjlong (66.74.169.186)
Rating: N/A |
Phil - Having the air compressor cycle on and off as you're traveling is normal. Think about it: The suspension's constantly moving as it conforms to the road's contours. Which also means the automatic leveling valves are also working, adding and discharging air as needed. As the air is used, the pressure drops until the governor tells the compressor to start the cycle all over again. I'd be far more concerned if the compressor DIDN'T cycle on and off!! As for your other questions: ~1. Dunno. . . But based on above, though, you may not have one. . . or it's buried somewhere! ~2. Not sure which tank this regulator gets it's air supply from, probably the one under the driver. But each tank in the system should have a check valve to prevent the backwards flow of air should an "upstream" tank fail. (The tank that feeds the suspension is the last one to get air from the compressor, which is why it takes so long to come up.) ~3. Yes, the idea is for the bus to hold air indefinitely. . . in theory. Reality is that it's virtually impossible! I've seen brand new MCIs lose their air pressure within an hour after shutdown, and others that will hold for days. Nature of the beast, me thinks. . . ~4. Depends on how much the suspension is having to "work" - rougher the road, the more air used. And don't forget that using the brakes brings down the pressure, too! Not to mention using the windshield wipers when it's raining outside. . . ~5. Lack of air pressure has no affect on the engine's fuel rack when shut off. The cylinder on the engine is spring-loaded to the "OFF" position. ~6. Keep your foot off the throttle when starting, basic idle is sufficient. What color is the smoke upon start-up? Blue? White? Black? Color makes a difference. . . Hope this helps. RJ PD4106-2784 Fresno CA | ||
| phil shannon (198.81.16.57) Rating: N/A |
Thanks RJ! What a relief to know that the air-ride suspension is not a closed system. After I read your answers I studied the air-brake component diagram and descriptions carefuly. Between what you have told me and what I have read, I know I can solve my air leak problem. My Air-ride system is tight, It will hold pressure for days, its my main air system that has a few minor leaks that I can handle one hose or component at a time. After reading the book I have made one quick observation, the pressure regulator/check valve for the aux air system seems to be letting air into the aux system from the moment I start the engine rather than after 65 psi is built up in the main system. I'll test the PRCV today to see if its shot or needing adjustment. Best, Phil PD4104-3832 |
