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Rattling At Low Rpms

1K views 16 replies 5 participants last post by  David99G20T 
#1 · (Edited)
Ok guys..

I'm not sure what is causing this rattle at extremely low rpms. If I put the car in second gear and drive at below 1,000 rpm I hear a rattle up until 2,000 or a little lower...I hear this in 1st gear too, but it sounds a little louder in 2nd. Is this because the engine is not completely stable at that low of an rpm range? I also noticed that if I'm driving up a driveway in 1st gear and push the clutch in and let it start to roll back and than let the clutch out push the gas and start to drive up..and if I do that back and forth I hear the sound too. I was thinking this was detonation, but I just had my timing set by the dealer, so I doubt that. I use premium gas and use range 6 NGK plugs and besides this sounds like a rattle and not a metallic "ping". I read it can be a heatshield, so I don't know. Is this a common noise? I heard this last night and a little, but not so much this morning. I'm wondering if this has always been there, but I just never have noticed it because I hardly ever drive in that low of an rpm range in a higher gear. I will try to post a video clip later.

Thanks for any help you guys can give!!

EDIT: The video is in post 6.
 
#4 ·
No, I haven't touched it. The last work I had done on it was a timing and idle adjustment and that was done by a Nissan dealer. I never noticed this before, but than again I never try to take off in 2nd gear from a stand still. I hear this in 1st, but its not as loud. It gets louder in 2nd and than 3rd, at low rpms. The engine gets more unstable at low rpms in higher gears right? That is why I'm thinknig that I hear the rattle louder as I go in a higher gear. Some times I hear this in reverse too lol..I noticed it, but not as much. I hear it in reverse when I'm trying to stall out the car, but give it enough gas to stay on while moving in reverse that is when I also hear it, so I doubt it's detonation.
 
#6 ·
Haha..yeah, I figured that too...the car has 188,000 or so miles on it..so I should change the motor mounts. how would I quiet the heatshield without removing it? The sound I hear is from the front drivers side (not sure if you can hear it from the passenger side)

Here is the video
http://s16.photobucket.com/albums/b11/98IntegraLS/?action=view&current=01-24-07_2125.flv

Sorry, it's a bad copy I took it with my phone and you can somewhat hear the rattle in the beginning of the video.
 
#7 ·
cant hear it but if its coming rom beneath ourcar I wouldsay yes heat shield bu you'd know rightaway to loo under you car but not know what to look for.

Front end Im almost positive its the mounts as my car does it too. Im repacing with OEM not aftermrket as the aftermarkets never need replacing again but vibrate like hell!
 
#8 ·
Yeah, sorry about that..stupid wind lol...Yeah, I can really hear it when I almost stall out the car, but still give it enough gas to move..and I can also sometimes hear it when I shift from 1st to 2nd as the rpms start to drop. I was just worried it was detonation, but than thought to myself that the rpm range where I hear the sound the most is too low for detonation (in my opinion)..and like I said..it's not a ping :cheese:
 
#11 ·
Ok, I think I pinpointed the sound a bit..lol..I drove with my door open to see if the sound was coming from under it. I knew the sound was coming from the bottom..just didn't exactly know where...and sure enough the sound somewhat sounds like it's coming from the bottom where the tire is. So, now I'm thinking it is the heatshield, but does the heat shield only rattle at certain rpms? Because I only hear the rattling at low rpms and normally in a higher gear than I'm supposed to be in..once the rpms steady out and are a little higher than 1,000 the sound goes away.

Thanks guys!
 
#12 ·
I think the lower RPM's will cause it to 'rattle' due toa slower vibration and maybe the higher PRM's make it vibrate more but faster which will actually cause it to 'buzz'...not saying thats the right reasoning/explanation but thats just what I think.
 
#14 ·
Update: I noticed it does this rattling sound in tune with the way the rpms are lol..if that makes sense..I rev a little and it seems as though it's rattling along with my rpms, but if I give it more gas it goes away. Can that also be the heatshield? Or if it were the heatshield would it not be vibrating in sync with the lower rpms?

Thanks guys!
 
#16 ·
i say motor mounts and can u tell where the shakin is coming from(left side or right etc)? get like a bar or somethin and apply pressure to each of the mounts. one at a time. and have some1 press on the gas a lil. see if it stops ^^. check for cracked mounts.
 
#17 · (Edited)
I'm starting not too think it's not the mounts..unless it is with a combination of the heatshield. One of my mounts looks warped, so I need to replace that one. As for where it is coming from. It sounds loudest with the door open and it seems to be coming from the drivers side. Either below by the tire or in the middle of the engine. Which is where some of the heatshield is, right?

Thanks again guys!
 
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