possibly from exhaust system
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1992 Audi 100 Question: really bad rattle under car. increases up to 40mph then quiets.
Answer #1pushrod October 21, 2013, 23:49Master
Broken catalyst in cat. converter i suspect. Possible heat shield also. Have vehicle hoisted and checked.
Answer #2csubak30 October 21, 2013, 23:55Master
Agree with #1, probably loose heat shield.
Answer #3Greg's Orange Auto (15380 Answers) , Orange, CA - (714) 361-9386globalhelper October 22, 2013, 09:11Master
poss cats or heat shields