Just wandering how long an air compressor should last and what are the diagnosis of one going bad. Got an X15 Cummins 565/2050 555000 miles on it. Think the air compressor is running too often. Can’t find any leaks, keeps pressure all weekend and over nights. Had the leveling valve off and over inflated the bags. No leaks. Then today I’m blowing coolant out. Pretty sure it’s the compressor pressurizing the coolant and blowing it out the pressure relieve cap.
Why do you think it's working too often? While it is possible and you always want to eliminate the possibility of air compressor issues, it's not common for the compressor to fail in a way that it pressurizes the cooling system. Possible, just not common. You can unload the compressor and put a pressure gauge on the coolant tank to verify.
Disconnect the main airline from the compressor, drain both air tanks and do a bottle test before you blame the compressor.
Cap/bypass the coolant lines to the compressor and bottle test. You can also test for Exhaust gas with the fluid detection method but must be for Diesel, gas engine fluid will not work. You are right at the mileage where dropped liner can become an issue on the high horsepower engines. More likely a dropped liner than failed compressor, but always eliminate the compressor before pulling the head. I have overhauled these at less mileage than yours for dropped liner in the past.
Most cases if the compressor is cycling often and you don't see pressure dropping on the gauges I'd be looking at a leak between the compressor and wet tank, along with the governor lines or gasket if its mounted right to the compressor.
Get a spray bottle with water and soap and go around spraying all the lines and fittings including the main line,governor,air dryer,and tank fittings.Even better if you have a pump sprayer.Some leaks come out fast enough where they don’t bubble so it would also be a good idea to find a quiet place to park and with the engine off walk around listening for a leak and also getting under the truck to listen under there as well.When you find the general area spray it and if it doesn’t bubble put your hand over the part until you hear it quiet a little bit.
