Have I killed my car?

March 27, 2011 10:14 AM

I was driving my '89 Toyota Corolla on a mud road when it bottomed out in a pile of gravel. At first everything seemed ok, but now, when I start the car, there is a loud vibrating noise (louder inside the car than out.) I also get the noise when I release the clutch into first gear, but not the higher gears. It has been a week now: I am not leaking oil or slipping gears and it doesn't seem to be getting worse. Other than the noise the car seems to be driving normally. Can you be my psychic mechanic?

Also, it seems like I can reduce the noise if I go into first at a higher rpm but that might be neither here nor there.

posted by ennui.bz to Travel & Transportation (12 answers total)

Your best bet would be to call in the popular radio show Car talk or research their site. Here is the link http://www.cartalk.com/. Good luck
posted by harigopal at 10:17 AM on March 27, 2011

Possibly the exhaust or muffler portion got banged up and is now slightly loose and knocking, this might not be a noticeable sound at speed.
When the car is cold, try jiggling the exhaust pipe with your hand. Any sounds?
When inside the car, can you tell if the sound is 'metallicy' or 'plasticky'?
Is it a turning/revolving sound?
posted by artdrectr at 10:38 AM on March 27, 2011

Just to be clear, the noise occurs when you crank the engine and when you shift into first but not when it's just idling? If that is the case then it seems to be related to the motor shifting in its mounts, so it could be a cracked motor mount, but it could also be some underbody shielding/fascia that got bent and rubs against something but only when the motor deflects enough.
posted by Rhomboid at 10:40 AM on March 27, 2011

Response by poster: Just to be clear, the noise occurs when you crank the engine and when you shift into first but not when it's just idling?

Yes, only when it starts and going into 1st. It's pretty loud and doesn't sound like sheet metal. I like the motor mount idea.
posted by ennui.bz at 10:51 AM on March 27, 2011

Pull into a quick oil change place and have them take a look under there... I would suspect exhaust, converter type of damage before I would think it's the engine...
posted by tomswift at 11:17 AM on March 27, 2011

Nthing exhaust system damage -- could easily be a heat shield on the catalytic converter has been knocked loose, vibrating audibly only at a low engine RPM. The fix may be as simple as cutting the loose part the rest of the way off and tossing it in the trash.
posted by jon1270 at 11:27 AM on March 27, 2011

Yep, probably knocked a heat shield loose. (I did it all the time, taking my 90 CRX on roads most people wouldn't take a CJ5.) Just about any mechanic should be able to handle it.
posted by notsnot at 11:56 AM on March 27, 2011

Another, slightly less common cause is getting some of the gravel wedged between the heat shields and the exhaust pipes proper. This happened to me on a trip to my friend's house, over a couple miles of rough gravel. Simply removing the heat shield and finding a bunch of rocks falling in my face gave the clue and the fix.
posted by jet_silver at 12:54 PM on March 27, 2011

This sounds exactly like my 1991 Ford Taurus when the motor mount was cracked.
posted by infinitewindow at 12:58 PM on March 27, 2011

This sounds like gravel caught in some components, and vibrating especially loudly at the right (wrong?) frequency. Probably nothing to worry about too much.
posted by Simon Barclay at 2:59 PM on March 27, 2011

What Simon Barclay says. This is a two-step thing, I'll guess. First, the force of the bottoming-out distorted the heat shielding a bit and... second, allowed a few pieces of gravel to be trapped between the heat shield and the actual exhaust pipe which are now the source of the ringing.
posted by bz at 8:40 PM on March 27, 2011

Oh... and the distortion of the heat shielding includes distortion of the heat-shield mounting which, in easy terms means: the heat shield is loose and infested with gravel.
posted by bz at 8:41 PM on March 27, 2011