On my 1984 Eagle 10, the rear air gauge on the dash sometimes only reads 100 pounds.Italso will read 120 at other times. I tap on it thinking it might be stuck but with no luck. It just started doing it recently. Any ideas???
eagle,
Same thing happened on my 4104. It was the air compressor governor.
Eventually the governor will fail to stop the comp at your set max air press and the press will climb all the way to 150psi Not good for the air system components.
I was just lucky that nothing broke or no lines ruptured.
The best part is the gov only costs about $20 at any truck parts place or, NAPA, and it is easy to replace.