Hi everyone, can anyone care to speculate on the source of this noise?

I have a 2007 Civic Si with ~97k miles. This sound has been happening for me for a while and it simply annoys the hell out of me. It only occurs on the first cold start of the day, after the car has been sitting overnight (and oil in head has had chance to drain). It's this anywhere from 1-4 second cranking/chatter noise...


Sounds to me like oil starvation in some way. But inspection of the engine has not shown anything to really indicate anything out of the ordinary. This noise started shortly after I bought the car used and decided to have the serpentine belt, tensioner pulley, and idler pulley replaced. There is no other issues with the engine other than this metal on metal marbles sounding rattle on cold start. A bit noisy on cold start (typical Honda valvetrain chatter), but runs like a champ once it's warmed up. Sometimes accompanying the noise, the RPMs will lag slightly with the noise before shooting up to 1800.

I have searched the interweb far and wide for someone who has encountered this before, and even my mechanic is stumped (next step would be bringing it to the dealership for troubleshoot but I am not looking forward to that). Here are the things I have had replaced in the past 10k miles or so in the search to eliminate the sound, to no avail. This has all cost me much more money than I have liked, so I come to Honda-Tech to ask the many knowledge people here.

Drive belt tensioner
VTC actuator
Timing chain
Timing chain tensioner
Chain guides
Valve adjustment

I've noticed that putting more oil in seems to remedy the problem somewhat (since the Si does burn some oil over time), but I often have to run much more than is necessary to abate it (maybe an inch above full dot on dipstick, whatever that is in qt's). The noise doesn't seem related to temperature as it happens year round and consistently ever morning on cold start. I only run 5w-30 full synthetic and OEM oil filters.

Anyone who might have some insight would be GREATLY appreciated! Thanks in advance.

 

Anyone?

Is this a sound that can happen if the timing belt tension is not set up properly or a bearing somewhere in the timing belt system (some pulley) rattling?

 

Why are you reluctant to take your car to a dealership? The techs see these cars daily, and know what's normal and abnormal. You have already spent a lot of money. Did you take the drive belt off, let the car sit overnight and check if the noise is present with the belt off?

 

Most likely the VTC. Google the TSB for the Accords about it. You can try cleaning both VTC screens first and see if that helps.