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I get a metallic rattling noise that's about a second long during some cold start ups. It sounds like it's coming from the engine bay. I checked the lower belly pan (sounds like metal rattling against metal) and they're tight. Any thoughts. After start up, it's gone.
 

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Allan Gibbs said:
I get a metallic rattling noise that's about a second long during some cold start ups. It sounds like it's coming from the engine bay. I checked the lower belly pan (sounds like metal rattling against metal) and they're tight. Any thoughts. After start up, it's gone.
Sounds like the timing chain is brielfy detensioned or something..could be related to the intake cam gear thingey too. Most likely it's a chain tensioner issue. Would tend to occur from a cold start after a long off period. Not 20 minutes after you just drove the car....more like overnight or days later.
 

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I started my car recently with other Elise owners around it.

My car did the 'angry alligator' 1 second rattle...

I asked the other Elise owners if they get that too once and awhile and each said 'yep'.

We all shrugged.

-doma
 

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Allan Gibbs said:
I get a metallic rattling noise that's about a second long during some cold start ups. It sounds like it's coming from the engine bay. I checked the lower belly pan (sounds like metal rattling against metal) and they're tight. Any thoughts. After start up, it's gone.
I have gotten something like that too a few times. Was really loud and nasty sounding, but only lasted for about one or two seconds. It hasn't happened for a few months.
 

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Stan said:
Would tend to occur from a cold start after a long off period. Not 20 minutes after you just drove the car....more like overnight or days later.
Exactly! That's it! So, I guess it's not something that's uncommon but is it a problem? I don't notice any issues while driving it (ie: no hesitation at idle or in the rpm range, no unstable idle, etc.)
 

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My Elise was making the same noise until just a few minutes ago. I just fixed it by tightening up two of my rear diffuser bolts. My diffuser bolts looked and felt tight, but they were not. The diffuser drops down as the bolts loosen and there is Locktite on the threads, so the bolts may not be as tight as they seem. Push up on the diffuser about 6 inches or so past the exhaust pipe (towards the front of the car) and look at the bolts to the right and left. The bolts have large washers, so they are easy to recognize. There should not be any play between the diffuser and the washers. If the bolts are loose, the diffuser panel will rattle against the washers when the engine vibrates during a cold start. Tighten the bolts and apply Locktite as needed.
 

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aletes said:
My Elise was making the same noise until just a few minutes ago. I just fixed it by tightening up two of my rear diffuser bolts. My diffuser bolts looked and felt tight, but they were not. The diffuser drops down as the bolts loosen and there is Locktite on the threads, so the bolts may not be as tight as they seem. Push up on the diffuser about 6 inches or so past the exhaust pipe (towards the front of the car) and look at the bolts to the right and left. The bolts have large washers, so they are easy to recognize. There should not be any play between the diffuser and the washers. If the bolts are loose, the diffuser panel will rattle against the washers when the engine vibrates during a cold start. Tighten the bolts and apply Locktite as needed.
Good point....only that woe will sound off at other times too. Some BMW E30 M3s are prone to an occasional chain rattle at start up. One fix is to load in a chain tensioner from an E36 M3. At least for that car, the tensioner is very easy to change out. Nice chain tensioner article & pics from a friend:

http://www.e30m3performance.com/installs/installs-3/tensioner/index.htm
 

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FWIW the timing chain tensioner costs like 25 bucks, is easily accessible, needs no special tools to install and is not a lengthy install.
 

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ChrisB said:
I get that noise, very infrequently, but it is attention-getting. Doesn't sound like engine-related to me. More large sheet metal vibrating (resonating). My diffuser is not loose, so :shrug:
I had a similar sound that became more frequent and much louder to the point where I was embarrassed to drive the car. Although it first began upon start-up, it eventually started happening at other times and was loudest when I decelerated from 3000 thru 2000 RPM while in gear. I thought it was the diffuser or something similar because it sounded like a "large sheet metal vibrating (resonating)" somwhere near or inside the engine compartment, but my diffuser was not loose. I also checked the heat shield and it was tight. I took it to Newport European, and on the second visit they found that the "shear panel" was in contact with the gas tank. Don at NE loosened the bolts to the panel, flattened out the panel so it wouldn't touch the tank and retightened the bolts. That simple!

I also had a crack in the Stage II tip bracket, but I don't think that was the source of this particular sound (large metal sheet rattle).

I'm happy to report that all the metallic rattling/buzzing is finally GONE! :nanner:

Take it to Don at NE!!
 

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Also might want to check the heat shields. Mine was loose when I first got the car.
 

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Oh this car has many sources or possible rattles...but a timing chain rattle has a certain sound to it, and pretty much will only happen after a lengthy off period. And then no more rattles while you drive, or maybe even for weeks. Something like an exhaust, loose panel, etc will be heard more often and can often be found by banging on things with your hand. Ya gotta be or hire a detective at times to find 'em!
 

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So the E36 M3's tensioner fits in our car? Safe to order it and expect a < couple hours to install?

thanks-
-dom
 

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Stan said:
Oh this car has many sources or possible rattles...but a timing chain rattle has a certain sound to it, and pretty much will only happen after a lengthy off period. And then no more rattles while you drive, or maybe even for weeks. Something like an exhaust, loose panel, etc will be heard more often and can often be found by banging on things with your hand. Ya gotta be or hire a detective at times to find 'em!
Lol. I have one that I just can not find for the life of me. I think it's coming from behind the plastic rear sill, but no luck quelching it yet. Comes on when the engine hits certain rpms triggering just the right frequency to set it off and in turn me. :mad:
 

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I think I have this same one, especially on deceleration rev down. it's a LOUD buzzzzzzzzzzzzzzz. sounds like it is coming from behind my head somewhere.

008 said:
Lol. I have one that I just can not find for the life of me. I think it's coming from behind the plastic rear sill, but no luck quelching it yet. Comes on when the engine hits certain rpms triggering just the right frequency to set it off and in turn me. :mad:
 

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doma said:
So the E36 M3's tensioner fits in our car? Safe to order it and expect a < couple hours to install?thanks--dom
No only a Bimmer thing...shows the nature of the issue though...u can change out a tensioner easily on most engines.
 

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Allan Gibbs said:
I get a metallic rattling noise that's about a second long during some cold start ups. It sounds like it's coming from the engine bay. I checked the lower belly pan (sounds like metal rattling against metal) and they're tight. Any thoughts. After start up, it's gone.
Just curious...have you installed a Quicksilver exhaust?
 

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vortrex said:
I think I have this same one, especially on deceleration rev down. it's a LOUD buzzzzzzzzzzzzzzz. sounds like it is coming from behind my head somewhere.
I have this same exact buzz also :confused:
 
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