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dmoney127
Advanced Member
USA
253 Posts |
 Posted - 02/17/2006 : 5:01:21 PM
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I'm starting to get a bit frustrated with a problem that my bus has been having, intermittently. It's a 1992 All-American FE with the 8.3 Cummins.
About a month or so ago, while driving in the morning, I heard a weird air-releasing type noise. I look down, and the air pressure gauges are pegged at the top end, well past 150 psi! The compressor would not cut-out...would just keep pumping. After contacting the shop and pumping the brakes to get back to a more acceptable pressure, the system didn't seem to have a problem again for the rest of the day. The shop replaced the air governor the same day.
Thought it was solved, until it happened again. The problem is, I cannot replicate this problem in the presence of a mechanic. They've even driven the bus on routes, and it hasn't happened for them yet. Now it looks like they are going to be driving it on routes (a few of them end up driving because of a small driver shortage) until they can get it to fail for them. I belive they have at least replaced the governor (twice), some of the lines, rebuilt the air dryer.
My question would be: is there anyone out there who has experienced this? It seems to happen randomly. Sometimes in the morning, sometimes in the afternoon. Seems to happen more frequently under heavy engine load (I drive in rural areas, so the engine is consistently under full load). I had a period this morning where the compressor wouldn't cut out for several minutes, despite me trying several times to get back to <120 in order to cut-out. Should the compressor be next to get replaced, or are there some other things that may be at fault here? |
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ModMech
Top Member
USA
948 Posts |
Posted - 02/17/2006 : 5:07:26 PM
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No, the compressor should definaytely NOT be replaced, or even suspected.
Most of the time this happens because either the discharge line from the compresor is blocked, or the signal line for the govornor is blocked or leaking.
Without full reservior pressure getting to the govornor, the govornor will keep the compressor on indefinately. Same with a blockage in the discharge line, no air gets to the tanks, and the compresor contiunes to run.
By the sounds of it, the signal line is the problem in your case, as the gauges show high presure.
There is NOTHING inside the compressor that can cause it to pump continually when the govornor has good signal and is working properly. |
If you want customer service, you NEED an International! |
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150+ PSI?
