I towed my camper up a hill the other week and heard a loud air-relief noise from under the hood for about 2-3 seconds.

I was going about 60mph, the boost was somewhere around 28-30psi, and I was heavy on the throttle while climbing the hill when it happened.

It sounded like an air compressor blowing air.

I thought I blew a coolant line.

I pulled over to check and couldn't find any leaks.

The truck Temps were fine and were still boosting the rest of the trip.

I'm not sure where the sound came from.

Is it possible that it was the fuel rail pressure relief valve?

I don't see any coolant leaks.

I visually and physically inspected the intercooler lines and couldn't find any tears.

Although i still want to do a leak-down test on the lines to be sure.

When I got to my camp spot, I did notice that the top of the fan shroud had melted.

When climbing that hill, the fan was spinning at full speed, and I could hear the fan roaring from inside the cab.

Does anyone have any ideas or different things I should check to find where that air sound came from?