Murphy's Visit: Investigating Sounds from My Honda Accord DX

[Gokul43201]

Murphy finally got to my car!

I own a 1992 Honda Accord DX (160K mi on it) that's been running fine until a couple days ago.

1. Now, when I start the car, for about the first half a second or less - as the engine comes to life - there's a rattling sound that I hear from the rear of the car. I'm fairly certain it's coming from the muffler or its vicinity.

2. During regular driving, this rattle is not heard again, unless I'm driving very slowly (<15mph) over a bumpy stretch, or if I do a not-so-smooth gear change at low gears. Makes me think something not too light (something bigger than a washer, small nut/bolt or chunk of rust) is loose in the muffler.

3. Another sound I hear is a low amplitude, medium pitch hum, or rumble, coming from about the same location that lasts for about a second or two in the lower gears (1 & 2). I do not hear it beyond about about 1500RPM (which is pretty low for a Honda). I do not hear this sound at all if my windows are up, or if I have the radio playing (so it's not terribly loud...but then, it's a Honda - the engine itself is as loud as a grumpy lion).

4. I think both sounds started appearing simultaneously, and neither is audible from the 3rd gear and up - not even when I floor the pedal on 4th or 5th (but the humming sound may just be getting drowned out by ambients).

5. Now, from a cursory inspection of of the muffler, I have the following to report:

i) The muffler is fairly rusted near all the weld joints on the inlet side.

ii) Shaking the muffler horizontally (by hand, so amplitudes were small - much less than an inch), made sound like there was a lot of loose rust chips on the inside. It was perhaps a rustling kind of sound. No clanging or rattling - but then, I didn't really thwack it up or down.

iii) The back plate of the muffler (I'll attach a crude diagram, if I can) had an outward bulge in the small portion just below the outlet pipe.

6. That last observation suggests to me that there may have been an engine backfire or some similar weirdness that caused this. However, if the engine did backfire, I didn't hear it. On the other hand, I don't think I've ever heard an engine backfiring in real life, so I'm not exactly sure what it would sound like. But the engine backfire theory is a little weak due to the observation in point #4 - or so I think.

So, what do you experts think may be the trouble? Any ideas or suggestions or questions? Should I go do an engine diagnostic? I don't have either the expertise nor the time to do anything more than rudimentary stuff myself, but I'd like to have an idea of the possibilities before taking the car to a mechanic.

HELP!

 

[Cyrus]

Sounds like a loose muffler, have it bolted down to the car. Engine backfire goes POP.

 

[Gokul43201]

Picture of bulge in the muffler :

http://img64.imageshack.us/img64/7409/mufflergu1.jpg

 

[Gokul43201]

Sounds like a loose muffler, have it bolted down to the car. Engine backfire goes POP.

Cyrus, I don't think the muffler itself is loose. I would have been able to shake it about if it was.

 

[Evo]

Sounds like it's time to get a new muffler.

 

[Gokul43201]

I do plan to get a new muffler, but I'm not sure if that's the first thing I should be doing. I don't want to change out the muffler before I know there isn't something else more fundamentally wrong - like an engine problem or a leak in the exhaust system. If that is the case, I might end up blowing out a new muffler from a recurrence of the real problem.

 

[Evo]

I do plan to get a new muffler, but I'm not sure if that's the first thing I should be doing. I don't want to change out the muffler before I know there isn't something else more fundamentally wrong - like an engine problem or a leak in the exhaust system. If that is the case, I might end up blowing out a new muffler from a recurrence of the real problem.

Do you know a reliable place that will check out the car and not rip you off?

 

[Gokul43201]

Do you know a reliable place that will check out the car and not rip you off?

Not really. That's the downside of having a well-behaved car - you don't develop intimate relationships with mechanics!

But then, what exactly is a rip-off? For a poor, struggling grad student like me, even a cautionary diagnostic that runs up $100 is something I need to think about before jumping into.

 

[wolram]

I do plan to get a new muffler, but I'm not sure if that's the first thing I should be doing. I don't want to change out the muffler before I know there isn't something else more fundamentally wrong - like an engine problem or a leak in the exhaust system. If that is the case, I might end up blowing out a new muffler from a recurrence of the real problem.

Ok, so are there any other symyoms? over heating, oil pressure light does not go out for some time time, engine using oil, have you changed gas stations, detonation is gas related, engine probleme are usualy rhythmic,
ie a noise is either there at at certain rpm or conditions under load if none of the above change your (cylencer)

 

[Gokul43201]

Ok, so are there any other symyoms?

Nothing that I can obviously tell.

have you changed gas stations, detonation is gas related,

I'm not really loyal to a particular brand. I fill up whenever I'm low and I pass a gas station with a name that's familiar.

Are you saying you concur that there has been detonation because of your independent evaluation of the picture or are you just going by my guess?

 

[wolram]

You must be methodical when looking for noises on autos, the main criteria is performance, is your car doing what it should do, if it is perfoming as usual ,
you can forget engine problems, (tentiavaly) you must note any anomaly, if there are none then , look for ancilaray problems.

 

[rocketboy]

My dad used to own a '93 Acura Integra, before we got rid of it it had almost 300k (km) on it. We experienced a similar rattling coming from the rear of the car, however for us it was the muffler loose and the sound came from the vibrating parts.

It may be something rattling inside the muffler, have you ever replaced it before or is it the stock part? (the muffler system I mean)

 

[Gokul43201]

Wollie: Other than the sounds, I can't tell any difference in the performance.

Rockie : I've only owned this car for the last 25-30K mi (abt 5 yrs). The muffler is not the original Honda muffler though.

I guess right now, I'll just change the muffler and see if that stops the sounds...and take it from there. With the warranty that comes with the muffler, if I do have to change it again, it'll only cost me labor ~ $25 or so.

 

[chroot]

Drive it until something actually falls off. Then, stop the car, identify the piece that fell off, and stop by the store to buy a new one.

- Warren

 

[Danger]

I own a 1992 Honda Accord DX

So, what do you experts think may be the trouble?

Look up. You just answered your own question.

 

[Moonbear]

Drive it until something actually falls off. Then, stop the car, identify the piece that fell off, and stop by the store to buy a new one.

- Warren

You're going to make him wait until something falls off? Geez, you could at least tell him how to temporarily stop hearing the noise...turn up the volume on the radio!

When the neighbors start giving you evil stares as you drive by, you'll know for certain it's the muffler that needs replacing.

 

[Gokul43201]

Smartass, Danger. Build me a car for $10K and give me an a 100K mile warranty on the drivetrain and engine and you've got a deal.

 

[Evo]

What kills me is seeing someone driving down the road with their muffler dragging and showering sparks. Can they not hear that?

 

[edward]

Not really. That's the downside of having a well-behaved car - you don't develop intimate relationships with mechanics!

But then, what exactly is a rip-off? For a poor, struggling grad student like me, even a cautionary diagnostic that runs up $100 is something I need to think about before jumping into.

A few things you can look for: Make sure that the exhaust pipe or tail pipe are not coming into contact with anything. If this should be the case some new muffler hangars would stop the rattle.

You can usually tell if the rattle is coming from inside the muffler by tapping it with a rubber hammer or block of wood. Tap on the lip (on the end) because the metal is thicker there.

You may also want to look at the catalytic converter. Most of them have a heat shield that can come loose.

 

[NoTime]

What kills me is seeing someone driving down the road with their muffler dragging and showering sparks. Can they not hear that?

A good car stereo will fix that

 

[NoTime]

Not really. That's the downside of having a well-behaved car - you don't develop intimate relationships with mechanics!

With 160K that's going to be changing.

All the water an engine produces pools in the muffler and eventually corrodes the interior.
The noises and bulging are common when this gets too bad.
160K says the muffler is stainless steel and its reached its life expectancy.
The pipes and converter may last to 300k or more.

Usually you can ignore this unless a bit plugs up the outlet, which will show up as a loss of power.
OTOH, you will soon have a hole in it, not good.

With a little experience and some fairly simple tools you can repace one in a hour or so.
Often less than the time it takes to deal with the repair shop.

If you have never done this it can take a couple days to work it through. And there are some details to consider if you want to try.
But, who ever said education comes easy

Be carefull of "Free Lifetime Replacement".
The labor is NOT included
Plus they are often plain steel which may be good for about 40K.
They also have a tendency to replace everything, needed or not

 

[BobG]

With 160K that's going to be changing.

All the water an engine produces pools in the muffler and eventually corrodes the interior.
The noises and bulging are common when this gets too bad.
160K says the muffler is stainless steel and its reached its life expectancy.
The pipes and converter may last to 300k or more.

Usually you can ignore this unless a bit plugs up the outlet, which will show up as a loss of power.
OTOH, you will soon have a hole in it, not good.

With a little experience and some fairly simple tools you can repace one in a hour or so.
Often less than the time it takes to deal with the repair shop.

If you have never done this it can take a couple days to work it through. And there are some details to consider if you want to try.
But, who ever said education comes easy

Be carefull of "Free Lifetime Replacement".
The labor is NOT included
Plus they are often plain steel which may be good for about 40K.
They also have a tendency to replace everything, needed or not

I'm not sure how easy it is to replace a muffler now a days - especially if you have to pass an emissions test. In the old days, new hangers, clamps and some sealer for the joints was enough. I think the joints are welded now to prevent emissions from the joints.

There is a benefit to making sure they install a better quality muffler and to replace any parts starting to wear out, since the labor is a major part of the cost. You'd want to know ahead of time which parts are nearing the need of replacement, since NoTime is right about a muffler shop having a different standard for 'nearing need of replacement' than you might.

Then again, at 160,000 miles, it might not be worth buying parts that will outlast the car itself. Tough to judge - if you take care of the engine, the transmission holds out, the body doesn't rust away, and you can afford to replace all the peripheral parts that die (starter, compressor for the air conditioner [optional], water pump, fuel pump, etc), you can get over 200,000 miles on a car.

 

[Danger]

Smartass, Danger.

Hey, it's my job.

 

[Gokul43201]

I'm not sure how easy it is to replace a muffler now a days - especially if you have to pass an emissions test. In the old days, new hangers, clamps and some sealer for the joints was enough. I think the joints are welded now to prevent emissions from the joints.

I think mine's welded. Last time I looked, I don't think I saw a pipe-flange anywhere nearby.

 

[NateTG]

Many reputable mechanics will do some diagnostics for free since it's a good source of business for them. If you can find a good mechanic, I'd advise going to the mechanic and letting him (or her) drive it around the block.

 

[NoTime]

I think mine's welded. Last time I looked, I don't think I saw a pipe-flange anywhere nearby.

While leakage is frowned upon, it has nothing to do with emissions. That's all about the catalytic converter which will be the first chunk back from the engine.

First step would be to read the manual specific to your car. The parts counter at the dealer will usually let you look at a pic of what you get when you order "muffler" from them.
For my 1999 car there are two sections.
One is the Cat with pipe welded to it.
Two is the muffler and resonator(a second muffler) and bits of connecting pipe welded to them.
The connection between the two sections is the old time slip joint and clamp, but its nowhere near any of the chunky parts.

When the side seam on the muffler split from corrosion at 155k, I picked up an aftermarket unit, cut the old muffler out with a sawsall, slipped the new muffler on the old pipe and clamped it.

To do this easily there needs to be 2 or 3 inches of straight pipe on either side of the old muffler. If the pipe bends immediately from the muffler then you may not be able to save any of the old section.

Also, explosion/backfire damage causes bulging in the middle of the muffler. In really bad cases it will start to resemble a beachball.

 

[Moonbear]

In the old days, new hangers...

Old coat hangers would work too. It at least keeps the muffler from dragging on the ground, so Evo doesn't worry about it so much.

 

[NoTime]

Old coat hangers would work too. It at least keeps the muffler from dragging on the ground, so Evo doesn't worry about it so much.

Add a tin can and a couple spiral clamps...
Good as new
Very important if your radio is on the fritz.

 

[Astronuc]

Add a tin can and a couple spiral clamps...
Good as new

When I was in university, I did that until I could afford to replace the pipe.

I need to replace the pipes and muffler on my Honda Odyssey. Price . . . $1400 (parts and labor). And the car is due for a new timing belt . . . $800.

Hey Gokul, how about taking the car to a Honda dealer?

 

[BobG]

Add a tin can and a couple spiral clamps...
Good as new
Very important if your radio is on the fritz.

That's because you're cheap. You don't have to use the same coat hanger that was stuck in the antenna's old socket. You can go get a different one from the closet.

Well, at least you used to be able to. I think just about all of my hangers are plastic, now.

 

[Gokul43201]

Update: Finally changed the muffler, and voila! - all the funny sounds stopped. Guess I was overanalyzing after all.

Thanks for all the inputs y'all.

 

[Moonbear]

That's because you're cheap. You don't have to use the same coat hanger that was stuck in the antenna's old socket. You can go get a different one from the closet.

Well, at least you used to be able to. I think just about all of my hangers are plastic, now.

It might cost more to take all your clothes to the dry cleaners to get those metal hangers than to just buy the bracket now. I think the dry cleaner still uses metal hangers, though I don't wear much that requires dry cleaning, so can't remember if I got metal or plastic hangers last time I used one. I need to put the hangers in my closet on birth control though. I don't know how they reproduce, but they're definitely multiplying.

 

[NoTime]

That's because you're cheap. You don't have to use the same coat hanger that was stuck in the antenna's old socket. You can go get a different one from the closet.

Well, at least you used to be able to. I think just about all of my hangers are plastic, now.

I would have gone to the closet, but at the time I didn't have a closet.