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What is wrong with my car?
June 23, 2014 6:44 PM   Subscribe

It sounds like I am riding a chopper.

So YANMM (mechanic) but I wanted to see if I could get some input before taking it in tomorrow. Today I was driving on the interstate and everything was normal but all of a sudden it sounded like someone nearby was driving a chopper or an intentionally loud sports car. Then I realized it was MY car. It's like a definite VRRRMM VRRMMM sound (very loud) and it happens when I press on the gas or accelerate but not so much when the car is going at a constant speed. It also happens when I shift gears (it's a manual). Everything feels like it's running normally except for the loud noise and the check engine light is not on. I have a 2001 Subaru Impreza. I looked underneath the car and as far as I could see there weren't any holes or glaring cracks in the muffler or the pipe that connects to it (not quite sure what I'm looking at though).

About a year ago my check engine light came on for a few weeks and when I brought it in they said it was the o2 sensor. It went back off and they said it was probably spotty. I didn't end up getting it replaced because I was kind of low on money and the check engine light didn't come back on. In retrospect I'm thinking this was probably a bad idea because some things online are saying the catalytic converter can do something like this when broken and I wondered if the o2 sensor issue could have led to a catalytic converter thing?

Anyway, any ideas on what this might be and how much it might cost to get it fixed?
posted by mermily to Travel & Transportation (8 answers total)
 
The exhaust downpipe is probably coming loose from the engine block. Car will drive OK except it's not muffled. Might be a matter of tightening the 3 or 4 bolts to spec, but even if so (and you may have lost some of them), you'd want to recheck in a month to see if they're getting loose again.

Could be a bunch of other things but it's likely that, especially if it gets MUCH louder when you accelerate as you say. If it's just loose or missing bolts it'll be an hour of labor at most, but a handy relative or friend could do it with some legwork to find the torque spec and get the right bolts if they're missing.
posted by kcm at 6:50 PM on June 23 [2 favorites]


MHIAM and he says it sounds like an exhaust leak. Go to a muffler shop, they specialize in that system.
posted by Jacqueline at 7:04 PM on June 23


hmmm. I agree with kcm, and add it might be the exhaust downpipe gasket. something unique to horizontally opposed engines
posted by bartonlong at 7:06 PM on June 23


Might be your catalytic converter! Someone stole ours and the car sounded like a Harley.
posted by masquesoporfavor at 7:16 PM on June 23


I don't think anyone stole their catalytic converter while driving down the interstate.....

Yes, it's an exhaust leak. The description of the volume suggests it is before the first silencer so relatively near the manifold (where it comes out of the engine). Take it to an exhaust place. No big deal.

I didn't end up getting it replaced because I was kind of low on money and the check engine light didn't come back on. In retrospect I'm thinking this was probably a bad idea because some things online are saying the catalytic converter can do something like this when broken and I wondered if the o2 sensor issue could have led to a catalytic converter thing?

If the engine light had been on for the whole time, then it could have affected the (finite, don't forget) life of the catalytic converter, but it wasn't. Don't worry about it. Also, Cat's do not make that kind of noise when they fail through lack of O2 control. They just fail emissions tests.
posted by Brockles at 7:34 PM on June 23 [3 favorites]


The three different 90s-early 2000s Subarus (92 Legacy, 98 Outback, 02 Forester) I've been acquainted with all had a heat shield under the engine that came loose, causing a loud and rather disturbing rattling sound that went away when the heat shield was removed.

The Forester also had perpetual O2 sensor problems caused by a defective catalytic converter for which there was a recall, sadly now expired. That didn't cause any funny noises though, just a check engine light that kept coming on. You probably already know that the check engine light will also come on if you drive around with a loose gas cap.

Subarus are great cars, though.
posted by mneekadon at 3:19 AM on June 24


Exhaust leak. Muffler shop.
posted by humboldt32 at 11:09 AM on June 24


Exhaust leak was correct! And the bill wasn't too devastating. Thanks for your counsel, Ask.me.
posted by mermily at 12:29 PM on June 24


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