Service slants

Motor, Mar 1998 by Juran, Ken

The noise sources may include the MacPherson struts, subframe insulators, stabilizer bar, steering and suspension pieces, powertrain mounts, brakes, tires and wheels, halfshafts, subframe and body. So where do you start? First, drive the truck with the customer to tune in on the noise. Once you've identified it, have a helper drive the truck while you try to define the noise and its location.

1. Clunk: Possibly a loose strut shaft nut, which allows the damper to jump when going over bumps. 2. Pop: Possibly a worn lower control arm bushing, allowing the arm to jerk when the brakes are applied. 3. Thump/Thud: Could be a worn stabilizer bar bushing or an internal strut failure. 4. Rattle: Possibly a bracket that's just begun to loosen up. Look for things like a wire harness retainer or a power steering cooler bracket that has broken free. 5. Squeak: A loose lower strut pinch bolt, which allows the strut assembly to move in the hub mount when turning. Also, a worn rubber strut mount bushing may squeak when flexed. 6. Creak: Could be a broken weld, either on a strut tower or on the cowl. Sometimes creaks can be duplicated in the bay by rocking the steering wheel back and forth from stop to stop, by jouncing the suspension or by power braking until the torque converter stalls.

Ford suggests isolating the noise to the left or right to get started. Then use a noise detector to zero in. Ford dealers use the Rotunda Electronic Chassis Ear (Part No. 107-R2101), which has six individual microphones that can be placed on suspect parts of the chassis. You can also use a plain ol' stethoscope with vacuum lines clamped to the suspect components.

On the body, inspect the cowl and fender areas and the radiator support. Around the control arms, check the arm and strut rod bushings and the torque on all the bolts. Go over all of the powertrain mounts and make sure their bolts are light. If you're inclined to go the extra mile, loosen and retorque the mount bolts to eliminate binding. Along the exhaust, check all the hangers and hardware. Make sure the front caliper mounting bolts are tight.

Carefully go over the entire front end and steering assembly. Especially important are the alignment plate spot welds (OE) or rivets (means an alignment has been performed). Check for gravel built up in the lower strut spring insulator. Trim it down, if necessary. Once you're sure the entire strut assembly is tight but the noise persists, replace the struts as a last resort. Check all the welds on the subframe. If you find a loose one, don't reweld it-replace the subframe. Note that there are revised subframe insulators available for Windstars built before 1/1/96 to eliminate a clunk, pop or creak in the floor pan on heavy acceleration or deceleration. These insulators have "nibs" that bite into the frame and prevent movement.

Finally, here are the most likely suspect areas to check for noises that occur while 1. going over bumps, 2. turning, 3. braking and 4. accelerating:

1. strut top nut, control arm, subframe, subframe insulators, hub, powertrain mounts. 2. subframe insulators, strut top nut, hub, stabilizer bar, control arm, steering rack. 3. brake caliper, hub, subframe insulators, strut top nut, control arm, control arm strut rod. 4. powertrain mounts, hub, exhaust system, subframe, subframe insulators, body.