I have an '04 Accord sedan with the 4 cylinder engine. Lately I've noticed a noise the engine makes at around 3400 rpm, it's like a metallic rattle, and then it's gone at 3500 rpm. I notice it before shifting to both 3rd and 4th gears, but not in 1st. I'm not sure if this might be a problem, or maybe the VTEC system kicking in or something to do with my changing from a 10W oil to the manufacturer recommended 5W/20. I never really noticed it before, but I usually had the stereo up so it might have been there for a while. The engine seems to run fine, but I'm a little concerned about this noise.

Anyone got any educated ideas?

 

I don't have any ideas but my car does this too. Did you ever find out what caused it?

 

Well, without knowing what sort of noise it's making, it will be difficult to say exactly what it its.

So, let's hope that it's not the same thing happening with mine.

I have a ticking / tapping noise when decelerating or accelerating lightly. If you keep the engine at speed, there is no noise. But lightly press the throttle or let off just a hair, and the noise is really loud. At first, it was like your situation, I only heard the noise at 3200 rpm, then I started noticing it happening at any rpm, as long as I was not holding it at a constant speed... After some searching and a few posts here a while back, one of the mods told me that it sounded like a connecting rod bearing to him. !!!!

Not a good thing at all, but I was already planning on rebuilding the engine, so not that big of a deal afterall. So, if this is what is happening with your engine, unfortunately, the only way to remedy this is to replace all your rod bearings.

Check to see if it happens at all rpms, in all gears, and make sure you've driven the car for a few minutes to allow it to warm up a bit. Mine doesnt do it for about 5 minutes after the car has been running. If you notice the sound each time you accel/decel gently, no matter the rpm, then you may have a bad rod bearing too.

 

I could be completely wrong, but we had a VW that had a metallic clanking noise when it changed gears. Took it in under warranty and it was just a loose oil pan clanking around. Recently get your oil changed. Just a thought, this could be completely trivial!

 

check your heatshields