Greetings! I have a 2004 Accord EX 4dr 4cyl. I have 145K miles and the car has developed a hissing sound. The sound is similar to what you would hear when you turn your steering wheel when the car is stationary - that power steering/hydraulic type sound. It could also possibly be the type of sound you might here if a piece of wire was gentling scraping on metal.It defintely sounds like it's coming from the front end. It only happens when I am moving, seems to pop up when the car is warm, happens more often when there is a change in road pitch (incline or decline) or on bumpy roads... though sometimes I can be driving along on a smooth, straight road and I will hear it. When I hear the sound and apply the brakes it usually goes away (sometimes gets louder for a split second before going way). This morning I was driving slowly on a bumpy road, heard the noise and turned the wheel back & forth which made the sound louder. I can't tell if it's a brake problem, rotors, wheel bearings, vacuum leak, shocks or whatever else. I am probably due for new brake pads so I will start there, but would love to hear if anyone else has experienced this. Thanks!

 

Sounds are obviously very difficult to diagnose over the net but give the fact that it only happens when you are moving my guess would be worn brake pads just starting rub that "squeeler" deal, you could try jacking up the front end and rotating it by hand to see if you can pinpoint it better... but brakes would be my first guess....

 

Thanks very much for your ideas. By rolling the windows up and down while driving I was able to pinpoint the sound was actually coming from the rear wheel on the passenger side. I jacked up the car and spun the wheel by hand and sure enough the brake pad was lightly scraping the rotor. I will replace the pads this weekend (first time I am attempting myself), but am wondering... why would the pad be scraping when the brake is not applied?

 

If you use your emergency brake (not sure if you car is an auto or manual tranny), then something mechanical could be locked up in the emergency brake system. If an automatic, then the piston in the brake caliper or the caliper pins could be frozen. You have to hit the brake to start an auto tranny car, and they rear brakes are not releasing the brake pad from the rotor. I think that your car has rear disc brakes and not drum brakes.

I would try to remove the two rear caliper bolts, clean the pins and the housing in the caliper bracket. I would grease the pins and see if the brake dragging goes away. If it is not the caliper pins, then the piston is likely sticking. You can replace the seals on the caliper or just get a new one. I wouldn't change the brake pads until you figure out if the pins or the piston are bad.

 

Yes, I use my emergency brake every time I park. I do have an automatic transmission and rear discs. Thanks much!

 

Also, depending on what pads you have a lot of newer pads have a little metal piece shaped like an L that starts to contact the rotor and rub and eventually make that loud annoying squeel to let drivers know that it's time top replace the pads... Are the pads thin or just rubbing?

 

OK - you were correct! The metal tab on the inside pad was touching the disc which was causing the sound. 2 questions: 1) any idea why the inside pad was much more worn out than the outside pad? Also, not sure if it's a coincidence, but the inside tread on that tire is also wearing out much faster. 2) I installed new pads and everything seems OK, but are the pads supposed to be lightly touching the disc when the brake is not engaged? I can spin the wheel easily by hand, but the pads are making contact. Thanks again for all your help!

 

How you describe the pads lightly touching the rotor sounds normal.

Do the caliper slide pins move nicely? If they were hard to move, that could explain your #1. Clean & grease them (if you didn't already do that).

Do the new pads fit nicely into the caliper bracket or are they tight? They should not have to be forced into place. I often have to file off a little bit (like the thickness of the paint) from the pad's backing plate to make them fit nice.

Uneven wear across the tread of the tire would be an alignment thing, rather than brakes.

 

The pins move nicely and I greased them up well. The new pads fit well and slide around easily. As it turns out both of the rear inside pads were worn down to the metal warning tab, while the outside pads still had quite a bit of pad left. Now my front pads look good, but I'm thinking the rotors might be warped because when I brake at a high speed the front wheels shake a bit. Before I go there, I will get the tires balanced because just driving at a high speed I feel a little shake - but it's much more pronounced when I brake hard. I have another problem with a loud engine rattle that I will post separately. Thanks!

 

inside tire wear is usually a negative camber problem. is the car lowered?
the brake pads are supposed to touch the rotor even when the brake is not being pressed. as you driveair will separate them andprovide a cushion between the two parts as you drive.