Rep Power: 0

Hi everyone,

I recently purchased a 2005 Honda Civic Hybrid with about 156k miles on the odometer. After getting it home and starting it after the engine had some time to cool down, I noticed the engine would produce a slight knocking noise when the engine was under load (accelerating), almost like a diesel engine. The engine appears to produce the noise while it is idling as well, but it is very, very slight. I will attach an audio recording for anyone who is interested. The sound didn't pick up great on the recording but you can hear it if you're listening closely.

After doing some research, I am 95% sure that the noise is coming from piston slap, which is apparently somewhat common on Honda 4 cylinder engines. However, I can't get a straight answer on whether it is a real issue or not. Some people say that piston slap requires an engine rebuild to prevent more serious damage, and others say that it is hardly an issue. Does anyone here know which one is right?

I noticed the engine was warm when I went to see it and I didn't think anything of it and now I'm kicking myself. You live you learn I guess.

 
Rep Power: 126

Sounds more like valve lash to me. Would be more probable on a 7th gen too.

 
Rep Power: 224

I would also try adjusting valves before worrying too much.

 
Rep Power: 0

Thanks to everyone who replied - I’m not convinced that out of adjustment valves are the issue as the problem goes away when the engine warms up. My dad has a 2010 fit that had the same issue and the problem was persistent throughout all engine temperatures.

I’ll probably adjust the valves anyway because that is (relatively) easy to do.