I recently bought a 1998 Isuzu Rodeo LS, Manual. Its got 95,000 miles on it, and until recently had no signs of an problem. However, in the last few days I've started getting a hissing noise from the rear of the car. It sounds somewhat like loud radio static, and increases/decreases depending on my speed. Maintaining a constant speed seems to decrease the noise, accelerating and decelerating increase it. I haven't noticed a drop in performance, but I've been babying it since the noise started.

Any ideas?

My best guesses are either rear differential problem or exhaust systems. Although I have no idea why an exhaust noise would increase during deceleration

 

I would guess at exhaust as well. Possibly a pinched tail pipe restricting flow and forcing it out somewhere else. I know about pinched tail pipes lol..


Other then that, put in on some jack stands and see if you can locate it that way. Its hard to diagnose noises without being under the vehicle.