Honda Insight Forum banner

Underhood "tinny" rattle

2K views 18 replies 8 participants last post by  jime 
#1 ·
I have a thin tinny sort of rattle from under the hood. The cat heat shield long since fell off, so not that. Had daughter listen while I raced the engine a few times, but it doesn't seem to make the noise under no load conditions. I seem to get the noise most obviously when I downshift to 2nd and apply some throttle, when the engine is at fairly low RPM and under some load. I looked at the famous firewall bracket, but it isn't broken and doesn't make noise at no load. Any guesses??
 
#7 ·
Are both heat shields missing? There's also a small one under/behind the cat. Exhaust bracket or the battery box/tray?
Thanks, I never knew about the small shield, but it was tight. I also checked the wiring bracket on the firewall that klr8cyl points to. I reinstalled the plastic engine cover, tighten up the spark plug bracket, but that didn't solve the issue. I will say that installing the cover seemed to attenuate the sound.

I also discovered that the rattle is RPM sensitive and occurs at approximately 1800 RPM under load.
 
#3 ·
On mine, there was a bracket holding the battery that had worked loose. Only sounded underway, particularly on left turns.
 
#4 ·
Jime is a left turn expert. Maybe that is it.!
(Med time)
 
#8 ·
Check the bracket that the fuel lines attach to near the firewall.
 
#11 ·
Yeah, I think you are right. It also makes it pretty frustrating since it could be almost anywhere in the engine compartment - as you say. I do hear the rattle at other speeds, but it is clearly resonate and much louder at about 1800 RPM. Thanks for the thoughts.
 
#12 ·
^ Here's another thought: I've noticed that the engine doesn't vibrate nearly as much as the transmission, such as at different engine speeds but not loaded. For example, the air box moves, rattles, a ton compared to the valve cover. I've put my hand on both to compare. I don't know why that's the case. I mean, you can press hard on each of these, valve cover and air box, and feel the source vibration - and that source vibration is so much more violent on the air box vs. the valve cover...

Sooo, I think this gets way exaggerated at that ~1800 RPM loaded juncture, so perhaps your rattle is more likely to be closely connected to the transmission side of things than the engine side?
 
#13 ·
Sooo, I think this gets way exaggerated at that ~1800 RPM loaded juncture, so perhaps your rattle is more likely to be closely connected to the transmission side of things than the engine side?
Yes, maybe. I looked at the transmission mount while under the car and that looks OK. I'll have to have a look at the motor mounts. I also looked around more for things which might be loose. Readjusted the hoot latch, which was too tight, but nothing helps so far.

I'll have a look around on the left side of the engine.

Thanks.
 
#14 ·
When my M/T 2000 Insight had a rattling noise on engine rev I looked everywhere. Sounded like a timing chain loose and hitting the cover. I recorded a video with audio and uploaded it here. Members immediately identified it as the input shaft bearing on the transmission. I replaced that (not easy) and the noise has been gone for 100k miles now.
 
#19 ·
Well my old racing buddy and pro mechanic located the rattle. Got it on the lift and had another pulse the engine. Turns out that the catalytic core in the second cat is loose within the can. First time I've ever heard that one;)
 
  • Like
Reactions: minor4326
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top