Sure, you are on the wrong forum, but here is my opinion.Help ASAP please!! New to the group and to owning a M925A2. In anticipation of the flooding of Baton Rouge from hurricane Berry I pulled the truck out to stretch its legs. Drove 10-15 miles last couple days w no issues but on a quick outing today started to get a “low air “ alarm. At idle truck maintains about 30psi and 40-45 at high idle. Crawled every inch of the truck and don’t have any obvious air leaks. Do hear what I think is some air from the drivers side of the engine but hard to tell when engine is running. ANY help would be greatly appreciated as rivers are expected to rise in the next couple days and truck is disabled in a lower spot.
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See the 1/4" line that comes out of the top of the compressor. Follow it up to the controller on the firewall, toward the passenger side. The control is about the size of a fist and has a plastic cap covering an adjusting screw. The control operates a valve in the top of the compressor. It gets water and debris in that line and affects the operation.
The obvious way to get them cleaned out is to take them both apart, clean and put them back together with fresh lubricant. The control is easy enough but the top of the compressor is a PITA. We will try the easy way on the compressor...but it may not work.
Take the line off at the top of the compressor and blow air from the other end. You should see some nasty stuff come out. If you can, find a way to funnel in some air tool oil (Marvel Mystery Oil) into the top of the air compressor while it's off so it can soak while you clean take apart and clean the controller.
Take the control off to clean it (very easy) Pay attention to the setting and after cleaning and a light film of lube (I use red grease) on all internal parts, put it back together with about the same number of turns on the adjustment screw and put it back on. You can fine adjust the air pressure later.
Now on the line that comes up, put it back on at the compressor and work more oil into that line at the top. Put it back together. Start it up and run it. Set engine rpm on the dash a little above idle speed. It may go up to pressure now...but there is no guarantee the lube has freed up the plunger in the unloader in the top of the compressor, you may have to give some "soaking in" time to the lube.
If it doesn't build to 110-120, stops at say 60, take the line loose at the top of the compressor and let it vent out while the truck is running. With that line loose you should have some air coming from the control valve and the pump should build pressure. While there are other safety relief valves, don't leave it off or pressure could go too high.
HOPEFULLY the oil and operation will free up the unloader and allow the control to maintain the 110-120 that you need.
The TM's have much more information, but this is what I would do.
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