Where is the rattle coming from, is it a plastic sound or a metalic sound? Coming from drivers side, passenger side or middle? Little more detail. Based on what you said, sure it could be the heatshields, or it could be anything else.
hey i had the exact same problem , the rattle was coming from the middle of the car, it was the heat shields, it had broken around the bolts, so i removed the bolt, puta large washer and put the bolt back in place, its so far solved the problem and the heat shield is in place, give it a try
__________________ 1998 328I
4 Door Sedan
Get under the car, find the heat shield and try giving it a little wiggle, it shouldnt move but as moe19x mentioned, the area around the washers rust and eventuly rust away leaving it unsecured, hence the rattling. If you can get the bolts off (assuming this is the problem) just stick some big washers on that cover the area thats been rusted away. But also as thekid said, a few more details might help, could be a worn flange holding the exhaust up thats rattling, or it could be a knackered cat, although that sounds more like crackling.
I've also had a problem where a piece of my heat shield had broken partially and was vibrating on the non-broken part. Eventually it just started scraping the ground and thats how I found out what it was, then I broke off the piece and no more sound. Granted it wasn't on my Bimmer but my old taurus, but it still could cause the rattle.
98 328i ECIS CAI / Tint 35% / 17" Gun-Metal Gray M Countour style wheels with Polished chrome lip and 235/40/17 Toyo Proxe T1-R's / Silverstar bulbs - head and fog
System - Calrion ProAudio HU / MB Quart RA 1000 Sub amp, RA 4200 4 ch amp / MB Quart PCE 213 5.25" seperates front / JL Audio VR 6.5" seperates in rear / Stinger SPDH5 Pro-Hybrid 5 farad Capacitor / Alpine Type X 12" DVC Sub in a slot ported box
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