2005 TL (26,000 miles) with an engine knock very noticeable after cold start up or next morning first start up. Ambient temp of 75F.

using premium gas with minimum octane rating of 93 from Costco (BP serviced stations) and amsoil Eao13 oil filter with semi-synthetic oil. About 1500 miles on the oil and filter.

Video recorded with microphone under the front driver side wheel well, the knock is noticeable on either side of the vehicle. It is however, not as noticeable from the top of the vehicle with hood open; perhaps the knocks are a little muzzled from all the valve train noise.

Sound of the knock is distinct at 1:30 - 3:00 during a period where the engine is revved from idle of ~900 RPMs (engine is still not fully warmed up) to ~2000 RPMs.

Sound of the knock is also distinct at 4:00 - 4:45 with engine revved at ~1300 RPMs.

Anyone have any clue on what this knock could be?

Many thanks in advance!

Video here: http://www.youtube.com/watch?v=bsGra4IGEgQ

 

It's hard to tell with the other noises. Many people will say to get the vavles adjusted, you could start with that, but at 26K, that's unlikely the cause.

If it's worse for the first few minutes and goes away or gets better as the engine warms up, it's likely a piston making the noise.

If it gets worse as the engine gets warm and especially under load, it's a rod bearing.

From the video I would have to guess a piston.

For the piston issue, you can try an oil like Redline that's very polar and tends to stick to parts better but it's a losing effort to try and solve it with oil.

If it's a rod bearing you can nurse it for a while on a thicker oil but if you're under warranty I wouldn't give them any reason to deny coverage.

Don't get your hopes up on Acura dianosing it. They will tell you they don't hear it or that it's normal or that you have to drive it until it gets worse.

 

Thanks for the reply, I hope its not piston noise or rod bearing I kept up with all the maintenance on the vehicle and for the first 23k miles, although I used regular oil and a Valvoline filter, they were always changed at 3000 mile intervals.

I guess I'll just have to take it in with my laptop and show the tech/service rep the video. Hopefully that will at least prevent them from denying the existence of that noise.

As for Acura doing anything about it, I have high hopes that they will at least attempt a diagnosis, but I think you are probably right, they are just going to tell me that it's normal.

I will update after I visit the dealership, any other comments/tips are welcome