I have two 6th generation Civics (see signature; all stock) with about 100k miles on the odometers. For both, at idle, I notice excess vibration of the vehicle and at the steering wheel when the A/C compressors are running. For the 00 Civic, the vibration is sufficiently strong to cause the muffler to make an annoying rattling/thumping noise. In both cases, the engine idle speeds are just fine with and without load, and the engines otherwise run pretty smoothly.

These observations lead me to believe that bad motor mounts/insulators are the root cause of the excess vibration. There are three motor mounts (circled in red: front right and left side mounts and rear mount), as well as two insulators (circled in blue: right and left). For the 00 Civic, the rubber portion of the front left mount may have leaked some type of fluid (?), and the rubber portions of both insulators for both Civics appear to be cracked/damaged.

My questions are:

1) Do I need to replace all of the mounts and insulators or will replacing only the insulators (and the ruptured mount) eliminate the excess vibration? I don't want to replace all the mounts if it is unnecessary.

2) Are there other possible causes for the vibration?

Any suggestions are welcome.

 

not sure about your question, but my front left mount may have also leaked some fluid, and I'm wondering what's up with that too. It was a black dirty fluid. I was taking an impact wrench to the crank pulley bolt to determine whether or not i'd need the special tool (which I do) and some black fluid came dripping down, and it took me a while but finally realized where it came from. I had no idea there was fluid in it...

 

Yeah, I assume that the motor mount is filled with some type of fluid and that it can rupture and leak. I think that Addiction mentioned a similar leak in his motor mount. Leaking must be a sure sign for a need to replace. I am hoping one of our motor mount experts, such as civicexracer, can provide some guidance for us. Otherwise, I may need to replace all of the mounts/insulators for my engines.

 

Holy shiz Ronj has a question!?? I didn't think that was possible lol. I have no clue, but I have a suggestion that isn't the mounts.
I have heard pf this problem before. I believe it was something like the idle control motor.The only reason I say this is because it causes your car to vibrate and worsen when you turn on the ac.
Remember that I'm not 100% on this I'm just saying what I can remember.
-Eric
Edit- I could be completely wrong though lol
It happened to my grandfathers car

 

Eric, thanks for the response. The fact that I make many posts and that sometimes my responses are helpful by no means indicates that I know everything there is to know about the Civic. I still have much to learn. In fact, many members that post less frequently certainly know more than I do.

My idle speed with and without load is perfect, so I don't think a malfunctioning IACV is causing my vibration problem.

 

Alright then its definitely a mount, or multiple mounts. Which I find odd; my reasoning being that it is a 2000. My aunt has a 92 civic with 200k and her mounts are still good. Funny how that stuff happens.
I say replace all dry-rotted/cracked insulators and only the ruptured mount. But if you are going for quality then replace all with aftermarket mounts. $$ $$

 

Thanks. This is the kind of feedback I am looking for. So you think that, based on age of the car, bad mounts/insulators are unlikely to be the cause of vibration? Why would you choose aftermarket over stock mounts/insulators? I am looking for the smoothest ride (least vibration) and thought that stock is best to achieve this.

 

For smoothest ride then go stock, but if you don't want to replace them for a long time go aftermarket. It most likely is the mounts, and even if its not you'll have piece of mind knowing they won't fail. I have a friend whose brother's mounts failed on him on an interstate. Needless to say it was bad.

As another suggestion for vibration- possibly the auto tranny?
Edit- Wait...Does it only vibrate while driving?

 

Interesting. For the 2000 Civic, shifting from Park/Neutral to Drive or Reverse when the engine is cold (higher rpm) and holding the brake can also cause some vibration even when the A/C is OFF. Can you elaborate further on this thought.

 

I'm not too sure. I just know that I've ridden in some auto cars that shake when stopped or shifting from neutral/park to drive/reverse although they (for the most part) don't shake while ddriving. I'm not sure of the route of the cause though.
Don't count out simple stuff that you couldn't normally think of either.