# Why is the car making that noise? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [June 13, 2015, 4:27am UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416 "2015-06-13T04:27:50Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![Mama\_Zappa](https://avatars.discourse-cdn.com/v4/letter/m/71e660/32.png) [@Mama\_Zappa](https://boards.straightdope.com/u/Mama_Zappa)\ **Post date:** [June 13, 2015, 4:27am UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/1 "2015-06-13T04:27:50Z")
1998 Honda Civic. Manual transmissIon. 175,000 miles. Check Engine light came on 2 months ago. Diagnostic says ‘Your catalytic converter is going’. Other demands on cash flow, so we put that off until this month. About two weeks ago, the car started making a kind of loud high pitched screech when we’re first putting out into gear, and for the first couple of seconds after that. This is both on starting out, and on upshifting while accelerating. My theory, it’s the clutch. Bearing in mind, this car is old enough to have its own driver’s license, and may not be worth repairing if it’s that expensive. The converter is 800 dollars; if we need to put a new clutch in, that’s more than the car is worth. On the other hand, it’s paid for and we certainly couldn’t get a good car for two grand. ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [June 13, 2015, 5:33am UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/2 "2015-06-13T05:33:21Z")
If it was the clutch then you should notice a slipping in gears: longer time when releasing the clutch to get the power you expect. Do you notice this? I don’t know how many belts are in this car, but to me it sounds like a slipping belt which could be fixed for like $60. 175,000 miles is a long time on one clutch though. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [June 13, 2015, 12:14pm UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/3 "2015-06-13T12:14:16Z")
clutch release/throwout bearing. ---
**Author:** ![Flyer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/flyer/32/7298_2.png) [@Flyer](https://boards.straightdope.com/u/Flyer)\ **Post date:** [June 13, 2015, 2:05pm UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/4 "2015-06-13T14:05:13Z")
Hondas tend to be very reliable. It wouldn’t surprise me if you could get another 50,000 miles out of it. “What the car is worth” is not always as clear-cut as people tend to think. If you look just at the book value, that’s one thing. If you look at it as buying transportation, that’s another thing. You know this car far better than you can possibly know any car that you might buy to replace it. Even if the repairs do cost $2,000, that still might be cheaper on a per-mile basis than buying another car. ---
**Author:** ![Typo\_Knig](https://avatars.discourse-cdn.com/v4/letter/t/cdc98d/32.png) [@Typo\_Knig](https://boards.straightdope.com/u/Typo_Knig)\ **Post date:** [June 13, 2015, 2:54pm UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/5 "2015-06-13T14:54:16Z")
Mechanic said the noise is from the catalytic converter, and everything else looks good. We’re going ahead with that replacement. ---
**Author:** ![QuickSilver](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quicksilver/32/7832_2.png) [@QuickSilver](https://boards.straightdope.com/u/QuickSilver)\ **Post date:** [June 13, 2015, 3:04pm UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/6 "2015-06-13T15:04:42Z")
Weird. What does the cat have to do with the transmission? ---
**Author:** ![crypto](https://avatars.discourse-cdn.com/v4/letter/c/b3f665/32.png) [@crypto](https://boards.straightdope.com/u/crypto)\ **Post date:** [June 13, 2015, 3:18pm UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/7 "2015-06-13T15:18:20Z")
Just out of curiosity… Would you be able to put an exhaust on the car without a catalytic converter? What I mean is, if you took the cc off the car before taking it into the shop, and said “replace my exhaust with a straight pipe and a new muffler”, could you get away with not putting a cc back onto the car? Unless the car wouldn’t pass emissions, how would anyone know? I am not suggesting everyone take the cc’s off their cars, but that is a hefty bill for a car with 175k miles on it. Plus, I don’t understand the connection between the sound you described and the cc. I would not be surprised if you have the sound issue after the cc repair. Keep us posted. ---
**Author:** ![Finagle](https://avatars.discourse-cdn.com/v4/letter/f/b19c9b/32.png) [@Finagle](https://boards.straightdope.com/u/Finagle)\ **Post date:** [June 13, 2015, 4:20pm UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/8 "2015-06-13T16:20:17Z")
> [@Stink Fish Pot](#): > > Just out of curiosity… > > Would you be able to put an exhaust on the car without a catalytic converter? What I mean is, if you took the cc off the car before taking it into the shop, and said “replace my exhaust with a straight pipe and a new muffler”, could you get away with not putting a cc back onto the car? Completely illegal. A bit of internet research indicates that a fair number of “stick it to the greenies” from Texas and Arizona do this and spoof the sensors, but in a state that actually inspects vehicles, it’s going to be a problem. ---
**Author:** ![Typo\_Knig](https://avatars.discourse-cdn.com/v4/letter/t/cdc98d/32.png) [@Typo\_Knig](https://boards.straightdope.com/u/Typo_Knig)\ **Post date:** [June 13, 2015, 4:50pm UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/9 "2015-06-13T16:50:16Z")
> [@QuickSilver](#): > > Weird. What does the cat have to do with the transmission? The symptom is a whirring noise after I shift gears, and a few seconds after. I am surprised at the analysis as well. Maybe something’s loose in the exhaust system that shakes when I shift gears. Maybe I didn’t explain it well enough in my note when I dropped off my car. The catalytic converter replacement needed to happen, unless we were dumping the car right away. Which we don’t want to. We only delayed it these few weeks because of cash flow. Idon’t want to pollute any more than I have to. We have emissions inspections here, and for good reason. Even if the car needs more work it may be worth keeping and repairing - we’ll see what the next bill is. The car is 17 years old, we’ve certainly gotten good use out of it. ---
**Author:** ![QuickSilver](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quicksilver/32/7832_2.png) [@QuickSilver](https://boards.straightdope.com/u/QuickSilver)\ **Post date:** [June 13, 2015, 5:42pm UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/10 "2015-06-13T17:42:58Z")
I hear ya. My 15 year old is in the shop now too. Mostly for scheduled maintenance and a thorough look around to prevent avoidable catstrophic break downs. I love that car and so I baby it. And while everything heats and cools and spins and shifts as it should, it’s starting to show signs of wear and the exhaust is blowing a bit, so I’ll be replacing that very soon, if not sooner - when the emissions and safety inspection fails. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [June 13, 2015, 5:56pm UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/11 "2015-06-13T17:56:46Z")
> [@QuickSilver](#): > > Weird. What does the cat have to do with the transmission? the engine sits on flexible mounts, and rocks back and forth a bit depending on whether you’re accelerating or decelerating. The catalyst is very close to the engine, usually within a few inches of the exhaust manifold, and typically attached using a ball-and-flare joint so the movement of the engine doesn’t fracture the exhaust pipe. if the converter failure is due to fracturing of the ceramic “honeycomb” substrate then the rocking of the engine could be causing the broken fragments inside the catalyst to ping and rattle. ---
**Author:** ![QuickSilver](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quicksilver/32/7832_2.png) [@QuickSilver](https://boards.straightdope.com/u/QuickSilver)\ **Post date:** [June 13, 2015, 6:36pm UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/12 "2015-06-13T18:36:32Z")
> [@jz78817](#): > > the engine sits on flexible mounts, and rocks back and forth a bit depending on whether you’re accelerating or decelerating. The catalyst is very close to the engine, usually within a few inches of the exhaust manifold, and typically attached using a ball-and-flare joint so the movement of the engine doesn’t fracture the exhaust pipe. if the converter failure is due to fracturing of the ceramic “honeycomb” substrate then the rocking of the engine could be causing the broken fragments inside the catalyst to ping and rattle. Wouldn’t it also rattle in a similar fashion going over uneven pavement? Heat shields can also come loose and rattle. Perhaps it does and the OP simply hasn’t noticed… Rattles are a genuine pain in the ass. Had one at the front end going over rough pavement. Thought it was a control arm bushing. Ended up being a broken brake caliper clip. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [June 13, 2015, 6:59pm UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/13 "2015-06-13T18:59:56Z")
> [@QuickSilver](#): > > Wouldn’t it also rattle in a similar fashion going over uneven pavement? Heat shields can also come loose and rattle. Perhaps it does and the OP simply hasn’t noticed… sure, but you wouldn’t hear it. too much other noise going on at road speeds. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [June 13, 2015, 11:40pm UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/14 "2015-06-13T23:40:31Z")
> [@Typo\_Knig](#): > > The symptom is a whirring noise after I shift gears, and a few seconds after. I am surprised at the analysis as well. Maybe something’s loose in the exhaust system that shakes when I shift gears. Maybe I didn’t explain it well enough in my note when I dropped off my car. On a manual transmission car that sounds like a throw out bearing failing. I have never heard a converter make a noise anything like that. ---
**Author:** ![excavating\_for\_a\_mind](https://avatars.discourse-cdn.com/v4/letter/e/e8c25b/32.png) [@excavating\_for\_a\_mind](https://boards.straightdope.com/u/excavating_for_a_mind)\ **Post date:** [June 13, 2015, 11:53pm UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/15 "2015-06-13T23:53:33Z")
> [@Finagle](#): > > Completely illegal. A bit of internet research indicates that a fair number of “stick it to the greenies” from Texas and Arizona do this and spoof the sensors, but in a state that actually inspects vehicles, it’s going to be a problem. Interestingly enough, the emission testing done in the high-population counties of AZ and TX are some of the most intensive in the country. I have heard they can be tougher than those in CA. ---
**Author:** ![SpeedwayRyan](https://avatars.discourse-cdn.com/v4/letter/s/ce7236/32.png) [@SpeedwayRyan](https://boards.straightdope.com/u/SpeedwayRyan)\ **Post date:** [June 15, 2015, 1:59pm UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/16 "2015-06-15T13:59:09Z")
> [@Mama\_Zappa](#): > > Bearing in mind, this car is old enough to have its own driver’s license, and may not be worth repairing if it’s that expensive. The converter is 800 dollars; if we need to put a new clutch in, that’s more than the car is worth. I don’t know how strict emissions/inspections are in your area, but you might be able to have a muffler shop install a “universal” catalytic converter on your car. These are WAY cheaper than the OEM part, and should pass all but the most strict inspections. The local muffler shop should be able to advise you on this. The universal ones can be very cheap, but even a direct-fit one that’s 49 state legal should be less than $200, and installation should be inexpensive. Check out this site if you need to track your own down and you live anywhere but California: [http://www.magnaflow.com/02catalytic\_converters/02product/49state.asp](http://www.magnaflow.com/02catalytic_converters/02product/49state.asp) ---
**Author:** ![Typo\_Knig](https://avatars.discourse-cdn.com/v4/letter/t/cdc98d/32.png) [@Typo\_Knig](https://boards.straightdope.com/u/Typo_Knig)\ **Post date:** [June 16, 2015, 2:33am UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/17 "2015-06-16T02:33:05Z")
Car’s back from the shop and sounds fine! Thanks, everyone, for the helpful and interesting responses! ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [June 16, 2015, 2:39am UTC](https://boards.straightdope.com/t/why-is-the-car-making-that-noise/722416/18 "2015-06-16T02:39:11Z")
Interesting diagnosis and cure. Glad everything’s fine.