1991 Jeep Wrangler Q&A
1991 Jeep Wrangler Question: why is the brake line whistling at fire wall?
The brake line should not whistle. If it is a metal line carrying fluid it may vibrate with some engine resonance if it is not properly secured. If it is a vacuum hose the check valve may have a problem, or you have a vacuum leak in which case the engine would run poorly. - patrick mannion