Have you checked the "flapper" inside the engine air intake assembly? The
flapper is attached with a "bi-metallic" strip to make it shut when the engine
is cold and draw warm air from around the exhaust manifold. When they get old,
they stop sealing, and can clang pretty loudly at idle. At road speed, the
thing will be held oipen by the air stream entering the engine, so it won't
Just a guess...
Sign-up for Ads Free at Mail.com