Hi all, I have 1999 Accord EX, I loaned my car to a friend a 2 months ago, he drove in really heavy rain. When I got the car back, I heard a noise whenever I'm driving, sounds like a hole in the muffler or exhaust pipe. It is especially when I'm driving fast, i.e. highways. When I set in neutral and step on the gas, no noise. Reverse, no noise. When I step on the gas and break at the same time, no noise. I had 2 mechanics look at it, they are stumped. I appreciate any help you can provide. Thanks.

 

do you hear the noise when the engine is hot or cold, does the noise go away as the engine get warm, or noise all the time when hot or cold. Possible manifold crack under the shield, take it off and check for exhaust leak.

 

The noise is there when the engine is hot and cold. Thanks for your help.

 

acmech52, is the manifold shield also the heat shield? I remember my mechanic took the heat shield off of the exhaust pipe because it was loose and rusted. The mechanic said taking it off is no big deal and it doesn't affect anything.

 

manifold heat shield to block heat from the hood. ( may affect your hood paint )
check around your exhaust area of all the shields to see if any are loose or missing, loose can cause a vibration with the wind and engine running at speed. put it up on jacks, block the rear tires good, and run it up to speed in gear with a very light brake pressure to see if the sound can be heard the same. Possible tire sound?

 

I'll try the things you mentioned. Maybe a defective tire? my front tires were changed a few months ago. Last week I had them rebalanced to see if that was the problem. I should try front and rear tires?

 

yes swap them back to front and check for same noise. Just curious, have you had any transmission problems on your car??

 

No transmission trouble at all while driving, the auto gear shifting have always been smooth. There were a few occasions when I was about to move the gears from to park to drive, I didn't press the break firm enough, and heard a loud click sound.

 

Thank You for the update.