Resonance
 

My 30 A five window coupe (I gave that info because it may or may not be revenant) has a resonance at about 1200 rpm/25 mph that is similar to driving your car with the back windows down. It is loud and uncomfortable. Makes conversation difficult. It is a kind of buffeting you can feel in your ears. Help! Any help!

Re: Resonance
 

Need more info.

If car is not moving how does the engine sound? Also, did it just one day start making this noise?

What is general condition of car?

Re: Resonance
 

Does your coupe have an interior? Ones without interiors are like driving in a tunnel. I usually put some kind of sound deadener behind the interior panels and that helps a great deal.
Marshall

Re: Resonance
 

Daren, check your exhaust system. If you have any place on that tailpipe, muffler, or exhaust pipe that isn’t supported by flexible, rubber supports, the vibration will carry to the frame. Even if everything seem Ok, it’s possible that with weight in the car something is touching metal. The exhaust systems on my XKE Jaguars were supported by springs, and they would resonate at 3200 rpm. It was a wonderful sound, but on a model A, I don’t think it would be pleasant at all.

Mike

Re: Resonance
 

The car is in very good condition. The interior is real nice. I can get this sound with the car in neutral by just revving the engine. The exhaust is sound (no pun intended). I know that if you modify the exhaust on cars/trucks you can get this annoying affect The muffler is a tapered unit although somewhat noisy. Perhaps the insides are deteriorating.

Re: Resonance
 

Disconnect exhaust. When I was younger we did all the time.

If your problem sound is gone. Job well done.

You might like how a Model A sounds without exhaust. Enjoy.

Re: Resonance
 

if you have engine splash pans installed, check to see if the mounting taps that attach to the engine have broken. They are prone to breaking due to vibration and will create a loud noise, especially during deceleration.

Tom Endy

Re: Resonance
 

Make sure you have clearance to the exhaust pipe as it makes it's first bend after the manifold. Contact there would make a lot of noise.

Re: Resonance
 

Engine pans...Hmmmmmmmmmm. I have considered disconnecting the exhaust just to see. The engine has been through a major overhaul and I do not recall if the problem was there prior. I only had the car a short time with other issues before pulling the engine.

Re: Resonance
 

MMMMM Might want to check the fan blades and hub for cracks. Look very carefully as the little buggers (cracks) can be hard to see. Sound waves can telegraph.

Re: Resonance
 

Be super careful with that fan. If it comes apart it can hurt you. Be sure it is tight to the pump shaft.

Re: Resonance
 

Very often the sound you describe comes from the exhaust pipe vibrating like others have stated earlier. There is a bracket that holds the tail pipe loosely and it will create quite a racket. To make sure that it isn't the source of your noise take a piece of shim stock or something similar and wedge it in between the tail pipe and bracket to see if that cures it. Be sure to remove it after you are done testing.

Re: Resonance
 

Re: Resonance
 

More ideas. Thanks.

Re: Resonance
 

As I read the OP, my first thought was "Exhaust clamp!" but when he mentioned hurting ears, I wondered whether winding up the window would help. Travelling with window down can cause a hell of a buffet. If that is the case, wind wings/deflector would probably be the answer.
If it is nothing to do with an open window, maybe have someone stand on the side of the road while you drive by in 1st gear with the vibration happening and see if they can pick at least which part of the car is the source. Maybe even someone driving alongside with their window down.
It's a difficult task to track down a vibration like that even if you are there. More difficult from here!:D

Re: Resonance
 

could be floor boards not sitting flat or somehting in the trunk/rumble not sitting quite right.

I know the noise your talking about. my 17 silverado does the same with the front windows down... jeep wranglers with a hard top are notorious for it as well. 18 tahoe i had as a loaner with the sunroof cracked made same annoying air buffering noise.

Re: Resonance
 

Have someone ride with stethoscope. Drive it with the fan belt off.

Re: Resonance
 

Windows up or down do not have an affect on it.

Re: Resonance
 

I had a loud, terrible noise coming from my car, and I asked Tom Endy about what might be causing it, and it was 2 broken tabs for the engine pans. At certain speeds, it sets of a kind of resonance due to the vibration and makes a lot of racket. Easy to check just to make sure.....

Re: Resonance
 

NHV (noise, harshness, vibration) is still a problem on new vehicles and a lot of TSB's are issued to solve such complaints which can be hard to track down. Every engine has its own RPM range that sets up vibrations of one type or another. A collapsed motor mount or a replacement with harder rubber, sheet metal cracks, a broken bracket, slight engine or drivetrain imbalance, worn bearings, etc. can set things off. Happy hunting!