Huu Quang Le

Honda Civic 2008 8th Gen VTi Sedan 4dr Strange Engine noise

The "knock-knock" noise has been around for quite a long time, and usually i just ignored it because there doesnt seem to be anything strange with the rest of the car. However, it becomes the biggest problem when i am trying to sell my car now as people just bargain for ridiculous low prices due to this noise. Therefore, please help me look at it and determine the problem so i can just fix it and get over with. My Honda dealer was unable to determine the problem and just plainly said "2000$ to replace the engine and -maybe- the noise will be gone" which is not really a comfortable option i can go with. Any help or suggestion is appreciated.


This is my first time posting, so if i broke any rule, please advise me and i will edit my post asap. Just want some help from the professionals.

RIPSAW

Give you a $100 for it.? HA..Sounds like something really deep. Like a rod or crank knock. Hard to believe a 2008 Honda would do that except from abuse. (Actually abuse is flooring it from green light to the next red light but most do not realize that) When you start it cold, does it do that? If not, it could be a cracked piston. Usually, when they have one, it sounds OK but as it warms up, it starts doing it since the piston expands and starts dragging harder creating for clearance in the pin to piston pin hole.

Drive it till it drops.
Or sell it only after discounting it heavy for a bad motor. It's fine for a round town beater. It may go 100K around town or 100 miles.. Who knows. I drove a Toyota Tacoma 100K like that around town. Don't unload it on someone who knows no better. Karma is real.

ezone

Oil neglect would be my primary suspect.

When the noise first began, I wonder how low the oil level was.....or how far overdue the oil change was.


OTOH the video only shows the engine idling. We don't know the engine temperature. I'd like to be able to hear it during a few other running conditions first.

But yeah, planning for an engine replacement would probably cover the worst case scenario.

Huu Quang Le

Thank you all for your advice. To be honest, i have never "abused" it or anything. It doesnt really matter if i start it cold or hot, the sound only happens every 2 or 3 days. And after letting it rest for a night, it just stopped making that noise. Then 2 or 3 days later, it pops up again. I never neglect my oil as i service it regularly. The noise was recorded the next day after a service even. But thank you all anyway.

Additional information: When i increase the car speed, the noise seems to reduce and it gets bigger when the car is in idling. The car itself is very smooth when driving, the only main thing was that noise.

ezone

An engine bearing problem (the typical bad rod bearing/spun bearing and such) would not be intermittent.

Bearing problems may be less noisy while the engine is cold and get louder or sound more severe as the engine and oil reach operating temperature......but a problem such as that would not just decide to 'heal itself' for one day and be quiet for that day, then be noisy again the next.


Can you use a stethoscope to narrow down a source area of the noise?
How does it sound when you work the throttle, raise RPM up and down? In gear, out of gear, accelerating, decelerating?


Use a wrench to release tension on the drive belt, that could tell you if the noise is caused by a belt driven accessory or not (compressor pulley bearing shot?) But don't run the engine long with no belt on it, you can overheat and cause damage really fast (less than a minute) if the water pump is not spinning.

Have someone hold the gas pedal at an RPM where the noise is loudest, then briefly disconnect ignition coil one at a time listening for the one that makes the biggest difference in the knock noise (usually would reduce or stop knocking) would prove internal engine issue and isolate which cylinder it's coming from...

Maybe possible carbon buildup on top of the pistons? That's about all I can think of that might make worse noise one day then less noise the next.

RIPSAW

From what you say, do what with ezone is saying. On you video, it's impossible to get direction from sound. Even there, since sound travels thru metal differently, its hard. Sure sounded like internal engine. But maybe all it is is a bad motor mount or the exhaust bent and tapping on something. Use a $5.00 Harbor Freight two ear mechanics stethoscope with long probe rod to narrow down a source area of the noise. Be careful around that drive belt. Lift the car and on jack stand inspect it playing close attention for exhaust clearance. Probe everything on engine and transmission.