last weekend did valve adjustment myself. since then my 97 accord performs perfectly at local speed. but on highway whenever i speed up to speed above about 60 mph, i can hear (suddenly, very clear appearance) a low pitch "hum" from the car. don't know where it is from. who can give me any hints?

 

the noise comes out very accurately above that speed. and there is no such noise when i just depress the pedal to speed up the engine speed when the car is at parking.

 

possibly drivetrain.

Here's a fun thing to do, kind of dangerous and requires a friend.

put it on jackstands, start the car, have your friend joe-blow sit in the car and maintain that speed while it's in the air, if the sound is duplicated, put your ear to everything drivetrain related (axles, wheelbearings, transmission, etc, etc.)

this might not work though, because some noises can only be heard under load.

it helps for things like wheelbearings though (I know this from personal experience)

btw, auto or manual?

 

automatic

 

Mijne did it too...

cuz I had painters tape on my tires...
yeaa I pulled the tape off and now its gone

 

sad, no painter tape on my tires.