Why does my car suddenly sound like a motorboat?

Discussion in 'Off Topic Discussion' started by ARCHIVED-Doenut, Oct 27, 2004.

  1. ARCHIVED-Doenut Guest

    Okay this may be the wrong place to ask this question but I figured maybe some of you know about cars. I drive a 90 Nissan Maxima, so I know it will make funny sounds and stuff will break and what have you, it's all part of owning an old car.

    However, a couple of days before I left for my cruise, I noticed that when I accelerated, the engine sounded louder than usual. Now it's really loud. It sounds like a motorboat or a go-cart. There is no change in performance, it doesn't hesitate, stall, or anything like that. It accelerates normally aside from the obnoxious sound. It also idles quietly, it's only loud when I press the gas. It seemed to happen practically overnight, it went from normal to loud within a day or 2.

    I tried putting a quart of oil in, I'm almost due for an oil change, but that didn't do anything. I really can't afford to get it repaired right now since I just blew a lot of cash on the cruise. Any idea what might be causing the noise?
  2. ARCHIVED-offta Guest

    Best to take a look underneath.

    Sometimes the tailpipe rusts off. It may be gone.

    Or, there might be a hole in the tailpipe.

    Some cars have a resonator ahead of the muffler. It could be that's all that is left.

    Just a thought. I've lost tailpipes my ownself.
  3. ARCHIVED-snak1313 Guest

    My first guess is a bad muffler.
  4. ARCHIVED-Zenlatin Guest

    I agree with the muffler. It could also be the catalitic converter. For some reason that part likes to get a rock hole in it and that makes it expensive as you have to replace everything from that point all the way out to the muffler.
  5. ARCHIVED-Braxas Guest

    Considering it hasn't lost any performance and it doesn't stutter at all I'd have to say the Muffler has gone bad. Check in the back, just look up underneat to make sure the muffler hasn't fallen off altogether. It's definitely an exhaust system issue - and I'd seriously doubt the Catalytic Converter has gone bad to that point - besides if the Catalytic Converter goes out on a car you'll smell sulfur - the car *will* stink. I had an old Mustang for my first car and the Catalytic Converter went out on it and god did that car stink! Of course my fix was to drive over to a friends house, pull the exhaust pipe off, take the catalytic converter out of the line and run it with straight pipes on the dual exhaust out the back. What a boost in performance - plus it was just a tad bit louder. ;) hehe
  6. ARCHIVED-offta Guest

    Don't know how much you know about cars.

    Your engine is run by explosions. Each explosion leaves smoke, etc. that must be carried off. The explosion occurs in the cylinder. The smoke, etc. (call exhaust) is sucked out of the cylinder into the exhaust manifold and from there to the tailpipe, from which it is sent out into the air.

    Along the tailpipe is the muffler. The muffler greatly reduces the noise from all these explosions going off in the engine. If it is gone, the engine sounds quite loud.

    Since the tailpipe is under your car and exposed to the elements, it is not uncommon for it to corrode, sometimes corrode so completely that your tailpipe will fall off. Since the muffler is part of the tailpipe, when it falls off, your car sound suddenly much louder.

    http://austin_america.tripod.com/sitebuildercontent/sitebuilderpictures/extailpiperesized.jpg
  7. ARCHIVED-Doenut Guest

    Thanks for the responses. I just have one more question.. can this cause my car to break down? Should I rush to get it fixed or will it run for awhile like this? The noise is annoying but I simply can't afford to get it repaired right now and I don't want to dip into my savings unless it's an emergency.
  8. ARCHIVED-MadameRocks Guest

    It shouldn't cause any major problems for a while yet...however if you start smelling exhaust inside the car while you're driving....then it's time to consider getting it fixed. If an exhaust leak starts, you'll smell it either in the car, or immediately when you get out and can cause a drop in performance.
  9. ARCHIVED-Elosia Guest

    /agree, it's either a missing part of tailpipe, or missing muffler, or a hole in one of the above.

    As for replacement, I had an '84 Saab 900 that I just let it go on for a LONG time, like a couple of years. I treaded dangerously close to failing the VET test with it in the state of disrepair, so depending on your state's laws, you may want to get it replaced soon if you have mandatory emission testing.

    Also, after leaving it unrepaired for a long time, I eventually started to have problems with the O2 sensor in the engine; I guess not having the emissions properly disposed of screwed up the sensor, which in turn started to cause hesitation etc. Realistically, if it's just a hole in the piping somewhere, it's not gonna cost too much, and you'd be well off just to get it done. If it's the muffler, it's a tad more expensive, but still not hugely so.
  10. ARCHIVED-shastadazymae Guest

    Once I pulled up to a red light, everything was fine. When the light turned green and I accelerated, suddenly I sounded like.. well, a motorboat.

    Turns out it was a muffler thing. Apparently it was some ring that holds a hose or a pipe in place that was loose or missing or something. Took it to one of those quickie places and they were able to fix whatever it was that needed fixin' while I waited, and it wasn't a huge expense. Just depends though.. had it been a hole in my actual muffler, which they suspected it was, it would've been a bit more money.

    Is there a dumpy little corner garage you can go to where they'd be willing to take a cursory look for cheap or free, just to tell you if you need to have it worked on right away, or if it can wait?

    d
  11. ARCHIVED-onomatopoeia Guest

    > can this cause my car to break down?

    No. The car will still run, probably even if the entire exhaust system falls off completely, although the performance would definitely be reduced. Your fuel consumption may be adversely affected for one of two reasons, first the amount of 'back pressure' generated by the exhaust system is changed which changes the flow of gas through the engine from what it is designed for, reducing fuel efficiency. Second, if the hole is very near the engine it will cause the exhaust gas to be sucked back into the inlet and used for combustion again. Since combustion of the fuel is achieved by combining with the oxygen in the air and the combustion process converts this oxygen into CO2 and other things which are no longer oxidants this means the fuel will not burn so well - leading to less efficiency and less performance.

    Failures in the exhaust system can take a number of forms. One of the silencers (mufflers) can rust through from the inside, this is particularly common if the car does mainly short journeys (less than 5 miles) so the exhaust does not get fully up to temperature. When a car is cooling down after running water condenses in the exhaust system, which can cause rust where is collects (often in one of the silencers). A good length run will cause this water to evaporate away, short runs will just mean that more and more builds up. What can also happen is on very high mileage cars the downpipe coming from the engine into the main exhaust system can hole at the bottom, just from continual exposure to hot gasses. It want on my 1986 Audi Quattro after about 160,000 miles and the car was REALLY loud. It gets louder when accellerating as there is much more gas flowing, when sitting at lights with your foot off the throttle (gas) pedal the valve that allows air into the engine is nearly shut, so very little gas is going into the exhaust system and out of whatever hole it has, when you accellerate the valve is opened and much more gas flows through the hole, so there is much more noise.

    You should consider what the construction and use laws are for motor vehicles in your country. The UK has a law of 108dbA at 0.5m as maximum noise level allowed, but also allows no holes in the exhaust system other than the intended one. Using a car with extra holes through corrosion means the annual safety / construction check will be failed, which leaves you on very shaky legal ground even if your existing certificate is not expired.
  12. ARCHIVED-snak1313 Guest

    If it's just a hole, you can get a patch kit. It might help for a month or two.
  13. ARCHIVED-offta Guest

    One reason the gasoline engine became more popular than the steam engine was dependability. The gasoline engine can be way out of whack and still work.

    Your car will just be loud for awhile.

    Unless the exhaust is prevented from escaping (ever see Beverly Hills Cop?), the car will run fine. Your ears may ring for awhile after you leave the car though.

    Be sure no exhaust come into your car though. It is poisonous.
  14. ARCHIVED-Daeloq Guest

    I just like to turn up the radio loud enough to mask any noises the car is making... :smileytongue:
  15. ARCHIVED-Braxas Guest

    A car will run fine without an entire exhaust system for a good long while. It'll just be really loud. I did that in that very same Mustang for about two weeks. I had dumped the exhaust system off because it was rusted out anyway and nearly falling off the car but still needed to get back and forth to work. I was lucky a cop never caught me with that. You don't know how loud a 289 really is until there is no exhaust on the car. ;)
  16. ARCHIVED-Grimgrey Guest

    It rarely affects performance, but depending on how zealous your local law enforcement people are you can get a ticket for it most places. (I had a friend who got out of his first ticket for excessive noise by pointing to the new muffler he had in the back of the car and saying he was on his way to get it replaced. That didn't work so well the second time - it was a few months later, and he was stopped by the same officer.)
  17. ARCHIVED-Zenlatin Guest

    Any updates Fran? Did you get a look under the car to see what might be going on? Or falling off? A hole or broken link is a pretty easy thing to spot and could save you a bit of money if you already know what is wrong.
  18. ARCHIVED-Doenut Guest

    No updates yet... I didn't even drive it yesterday (worked from home). Still loud though. I'll get it looked at next week (I get paid tomorrow). Thanks for all the info guys.

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