My car is making a sound like a rattle or a knock. I have never had an issue like this before and as soon as I heard it I parked my car and refuse to drive it. I have been told that it is low end and could be a valve or rod. I have done a little test with my ear on different parts and I do hear it around the engine however I also hear it on the pulleys. My main question is can the water pump or timing be causing this knocking sound. I have only put honda full synthetic in the engine and I have driven hard but not insane. I also heard that it could be a spark knock from low octane so I put some booster in my fuel and changed the oil to check for metal shavings and see if the noise would dampen at all. I have noticed no metal after taking a magnet to the oil and I have not noticed a dampen in sound. The noise occurs during the start up right at 1300 rpms. But as the car lowers it rev to idle the sound will go to a very faint sound. I can also hear it when I rev the engine slowly. I did drive it one time when I first noticed it and I did not see or feel a decrease in power. I can add that I have moved around alot since I bought the car from San Diego to Wa, to Kentucky and trips around those areas. The vehicle has 61k miles.
Any help or possible touble shooting ideas would be great. This problem has gotten me so down that I actually rarley drive my Jeep I actually just bike to work now lol.

2009 Honda Accord EX-L V6 Auto.

 

Diagnosing it - go to an auto parts store and get an auto mechanics stethescope [or Harbor Freight (<$9)].
These things are amazing at pinpointing where a mechanical sound is coming from.

Luck.

 

I used a stethescope to pinpoint this noise (click on video below). Changing the timing belt components solved the issue.

 

There was a Honda technical service bulletin (TSB 08-017) for engine knock or ticks at idle. The cause was the rocker shaft bridge having excessive clearance which caused the rocker shaft to rotate and make noise. The fix was to loosen and retorque the rocker shaft bridge bolts.

This may or may not be related to your problem and may not apply to your vehicle. Note that TSB are not recalls unless stated as such; this was not a recall. The TSB are for properly trained technicians and not intended for DIYer's.

Honda TSB 08-017

 

Ok so I just wanted to ask you a follow up question here. Does Honda fix this at no cost or is it a fee based fix? Thank you for your help.

 

Thanks man, I have been putting it off I suppose I will be doing that this weekend.

 

As stated, it is not a recall. If you are no longer under warranty, there is a charge for diagnostic and service.

 

I just wanted to follow up, I finally got around to get the stethoscope and did more diagnosing and only spent $1.99 on the thing. So I seem to hear the noise loudest on a pulley on the timing belt. I cannot disconnect the pulley without potentially messing up the timing so I am going to be taking it into a mechanic. I am not sure if a bad pulley can cause the engine to knock or rattle but it seems really plausible at this point. I also noticed a small strip of fray on the belt. Let me know if you have any ideas, I will probably be taking it into the shop her in the next couple of weeks.

 

Can you post a pic? The timing belt and gears are behind covers is why I ask.

 

The rattle I finally resolved in my V6 05 Accord was eventually found to be the belt tensioner pulley assembly. Difficult to pinpoint where the noise was coming from at first but eventually found it. Mainly occurred when at idle only. $80 for the replacement assembly at auto store and about 2 hrs max to replace. Two bolts, one on the lower pulley and the other is a small one that is hidden below the unit. If you remove the right wheel, you can access it from the inner fender area with a long socket extension quite easily. Turns out there is a dampener on spring tensioner assembly that wears down over time. Dampener works mainly at little to no load on the engine when vibration is present. Check out www.gates.com and search "tensioners".