Camry in the rain

i have a 1996 camry with a v6. it has 235k miles and i drive about 100 miles per day. i’ve had the car for about 2.5 years and in that time have driven about 70k miles.



recently, its started some strange behavior in heavy rain. the vehicle starts making a loud humming noise about 1-2 minutes after heavy rains begin. the longer it is in a heavy rain, the louder the noise is. there isn’t any vibration, just the noise. the noise does sound like it is coming from the engine compartment and when i let off the gas, the noise goes away. i’ve heard the noise at any speed from 45-80mph.



i crawled under the car to look and see if there is anything obviously loose, leaking, bent, etc, but nothing was out of the ordinary from previous trips under. i change my own oil so i get a good look at the vehicle on a regular basis.



one last thing, i also hear a ‘bobble’ when the rain gets bad. usually this happens when i hit some kind of a slight dent or ridge in the pavement. there doesn’t seem to be any conjunction with the other noise except for the presence of the heavy rain. this noise can come from either the front or the back of the vehicle.



so, there’s the puzzle. anyone have any thoughts?

How old are the spark plug wires?

only about 6 months. the car doesn’t actually lose any power or miss or anything.

You might have a cracked exhaust manifold.

Years ago, my Volvo from Hell exhibited the exact same noise problem when driven during a heavy rain storm.

that had not even crossed my mind as a possibility. thanks for the tip. i’ll check it out.