Galaxie500XL Posted October 23, 2012 Report Posted October 23, 2012 My '95 LQ1 has an annoying metallic rattle between 1800-2300 RPM. First thought was the heat shield under the car, above the catalytic converter, but it seems to be tight. Any ideas of what else might resonate at around that RPM range? The car sounds like I'm rattling a coffee can full of rocks at that RPM, it's most noticeable in 1st and 2nd gear...the powertrain makes no nasty noises at all above and below that range. Quote
94 olds vert Posted October 23, 2012 Report Posted October 23, 2012 Possibly the Cat? If the baffles inside have separated they can rattle around. Quote
Galaxie500XL Posted October 23, 2012 Author Report Posted October 23, 2012 I've long suspected the cat...but the noise sounds as if it's coming from the front of the car, rather than underneath...but that is a good possibility. Possibly the Cat? If the baffles inside have separated they can rattle around. Quote
19Cutlass94 Posted October 23, 2012 Report Posted October 23, 2012 What about the heat shield by the downpipe? Quote
Leo090 Posted October 23, 2012 Report Posted October 23, 2012 Do you have any change in performance? or temperature? Is it only on one side of the car? Maybe a loose hubcap bolt. Quote
rich_e777 Posted October 23, 2012 Report Posted October 23, 2012 My exhaust leak sounds similar to that, I described it as having marbles rolling around in the downpipe. Fubar Donut gasket at rear exhaust mainfold? Ive got 3100 but im sure mine has the same sound. I bet you cant replicate the sound unless you have it in gear and moving basically under load. I had mine jacked up over the weekend and put it thru the gears and couldnt make it as obvious as when i accelerat from a stop. Im still trying to get a break from work to fix my baby, Head gasket and the rest above it so i`ll have new exhaust gaskets all the way around and should be good to go from there. +new radiator. Got to keep these things on the road, these new cars are a complete eyesore. Quote
Galaxie500XL Posted October 24, 2012 Author Report Posted October 24, 2012 I'm leaning toward the cat...the donut was replaced by me when I did the power steering hose... One thing I hadn't noticed until last night--when the car is first started, and cold, it's quiet. The noise only appears once things get up around normal operating temperatures..but oddly enough, I don't hear the rattle at highway speeds, even though the engine is turning around 2,000 RPM at around 62 MPH. Of course, it could be the noise is there, but being a convertible, road and wind noise drown out the sound.. Quote
Psych0matt Posted October 25, 2012 Report Posted October 25, 2012 Cat, 100%. My cutlass had it, now my monte has it. New one fixed it right up. In the spring I'm throwing my new downpipe/cat on the GTP and putting the GTP one on the monte Quote
rich_e777 Posted October 29, 2012 Report Posted October 29, 2012 any paricular brands of Cat. Conv. that hold up or provide better performance/sound over OEM recommended? And would anything else make this same or similar sound that hasnt been mentioned? Quote
94 olds vert Posted October 29, 2012 Report Posted October 29, 2012 Maganflow high flow cat is what I would get. Quote
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