jdawgzcivic

Hello,
I bought a 2003 Honda Civic LX Coupe for my daugher several months ago and so far I have replaced the following:
Motor Mount
Shocks & Struts
Timing Belt
Water Pump
Oil Pan Gasket
Wheel alignment performed

It has been running solid without issues except for the past month when it “rains” the car starts to “vibrate” very hard and can’t determine where it’s coming from. Very strange that it only happens when it rains. When it rains, the vibration starts while running as well on when I’m stopped and also as a test placed on “neutral” but this sound becomes pretty loud. You can feel the vibration on the armrest portion of the Civic.

The Civic has a custom installed muffler - the one that makes the sound.

I’ve tried putting the car up and letting it run for about 30+ minutes but the noise/vibration does not happen since it’s not raining. Before I bring it to a “dealership” or a “auto-mechanic”, I know it will not do it unless it rains.
Any help and suggestions are greatly appreciate.
Thanks in advance.

CraigW

iTrader: (1)

^^^ Likely place to start.

jdawgzcivic

What do you recommend?
Go back to stock? or replace with another after market muffler?
How much to you think it will cost for either one?

ezone

Garden hose+ strategic squirting, to narrow down to a specific area.

mac25

Does it have an aftermarket intake?

I noticed when I drove my car when it was automatic with a cold air intake nearly touching the ground, when it rained, there would be a grinding noise.

when I went back to a short ram air intake, the noise disappeared.

CraigW

iTrader: (1)

Is the muffler the only part replaced ??

Definitely a job for specialized shop. I'd put original back.

jdawgzcivic

The intake is stock - I checked under and saw there were a few "holes" on the muffler.
I sealed them and give it a try and get a garden hose and see if it made a difference by patching the holes.

jdawgzcivic

It looks like the previous owner put this "muffler" in and it was lowered. So when I checked, saw a few holes on muffler. The muffler is the one that makes the "noise" and the hole is bigger than the stock. I hope by patching the holes will fix it. Can that be the difference? If water gets in the muffler, it will start to vibrate? Will let it dry and then will try using a garden hose and see if the problem of vibration still happens. Can feel it on the passenger side and on the armrest. Will send update

jdawgzcivic

Update:


After heavy rains, the issue has returned and vibrates very loud.
There is no vibration or issues when it does not rain.

Wankenstein

Notice any wet spots in the cabin after it rains? Maybe there's a leak and water or moisture is getting into the ECU/PCM or other electrical component (ex: sensor) that causes an issue that results in vibration.

OP..Did you say the car suspension is lowered or just the muffler? Possibly gets wet from underneath from wet roads and effecting an electrical component or air intake.

Read this: https://www.civicforums.com/forums/3...hen-rains.html

Looks like your not alone in your car's issue: https://www.google.com/?gws_rd=ssl#q...+when+it+rains

CraigW

iTrader: (1)

So same muffler ?, just patched the holes in it ??

jdawgzcivic

Where or what is the ECU/PCM? the car also has an after market muffler and patched the little holes. When it rains heavy, the rattling and shaking happens. I also placed the original struts and spring back on the civic.
Interesting, so it's not just this car.

Thanks

jdawgzcivic

Yup, same after market muffler. Very strange only happens when it rains heavy and the car just shakes and rattles very loud.
Looks like it's not just happening to this car. Could it be something with the bushings, catalytic converter getting wet? I have new motor mounts.
Even if stopped on a light, the car was vibrating very loud when it was raining hard.


Thanks

jdawgzcivic

Update:


Went to different auto shops and another auto shop specializing in mufflers


The muffler shop noticed that was no "gasket" in between the muffler in the back and the joint. Now, installed the gasket in between.
All auto shops then raised up the car and in started the vehicle. Sprayed and used water hose to see if it will do it again. All auto shops when it was raised up did not make the noise. Sprayed all over and under the vehicle and no noise. So I'm not sure if the missing "gasket" on the joint which was pretty noticeable.
Or now, just have to wait for heavy rain. If it rains heavy again, could it be "moisture" that is triggering the noise to some electronic components or spark plugs?


One auto shop did a test and placed a cut off hose about 3 feet and placed it in the exhaust manifold while the car was raised up and running. You can hear the "leak" and "noise" when placing the other end of the hose to the exhaust manifold. Could this be also causing the vibration due to this exhaust manifold leak?
Can this be replaced pretty easily like if I do it myself? I did the brakes for this Civic. Wanted to find out if this exhaust manifold is a complicated process.


Thanks

NDNV

Take a look at your middle (B) exhaust pipe and find out where it is hitting the chassis when it rains. The exhaust system gets cooled with the rain water that gets splashed over it. The exhaust gases in the pipe actually get condensed in the pipe and therefore causes back pressure on your engine and hence the vibrations through the exhaust pipes. There was a TSB out for this issue way back when from what I read. Solution was to replace the B exhaust pipe or modify the existing to increase clearance from chassis.

jdawgzcivic

Thank you very much for the info - this definitely makes a lot of sense and now can understand it better. Do you think I need to replace the entire exhaust system or is there something that can be sprayed on to the exhaust on the outer exhaust? Also one of the mechanic said there was a leak on the exhaust manifold. Is this very hard and difficult to do?


What is the B exhaust pipe? is that the middle part?
A is the manifold exhaust and C is the muffler end?


Thanks again.
Greatly appreciate it.

NDNV

I would find the TSB and see if the solution was to just replace the B pipe (yes, B is middle and A is engine end and C is muffler end). You may be able to take to an exhaust shop to bend it but depending on the age and condition of the existing pipe, you may just replace and be ahead.


Also check the aftermarket muffler for clearance issues as well.


As for the exhaust manifold, you will need to address this soon as well. I would search on "exhaust manifold leak" for more info on that topic.

PMcCann1

Look up Torque Converter Shudder symptoms. A quick tranny fluid drain & refill with Honda Brand ATF from dealer (3 quarts @ $6) will solve your problems. Get a new drain bolt washer while your there too.