Ok folks, this one is weird.
05 express 3500 box truck. I was checking my tranny dipstick with the engine running, and was noticing a high pitched whistle all of a sudden, like a leaking vacuum hose. The dipstick was pulled out. Upon listening more closely, the whistle was coming from the dipstick tube itself. No transmission fluid spurting out or anything. I covered the tube opening with my thumb, but couldn't feel air sucking or blowing. The whistle stopped too. When I uncovered the tube opening, the whistle came back and at much higher pitch, then shifted pitch down, then again resolving to the original pitch of the whistle (as if there was pressure being built up when I plugged the opening with my thumb, then released).
It sounded like a flute....
Obviously there's something pressure wise happening here, but I've always heard the bad signs when there's air coming out of the tube, mainly the oil.
Again I couldn't feel air, and fluid wasn't spraying out.
Any thoughts on this? Vacuum leak on the other end maybe? No codes or leaking tranny fluid....
05 express 3500 box truck. I was checking my tranny dipstick with the engine running, and was noticing a high pitched whistle all of a sudden, like a leaking vacuum hose. The dipstick was pulled out. Upon listening more closely, the whistle was coming from the dipstick tube itself. No transmission fluid spurting out or anything. I covered the tube opening with my thumb, but couldn't feel air sucking or blowing. The whistle stopped too. When I uncovered the tube opening, the whistle came back and at much higher pitch, then shifted pitch down, then again resolving to the original pitch of the whistle (as if there was pressure being built up when I plugged the opening with my thumb, then released).
It sounded like a flute....
Obviously there's something pressure wise happening here, but I've always heard the bad signs when there's air coming out of the tube, mainly the oil.
Again I couldn't feel air, and fluid wasn't spraying out.
Any thoughts on this? Vacuum leak on the other end maybe? No codes or leaking tranny fluid....
