Suspension/Engine Mount - Loose/Rattle Lumber Noise
File In Section: 3 - Steering/SuspensionBulletin No.: 53-33-04B
Date: November, 1997
Subject:
Rattle/Loose Lumber Noise from Front of Vehicle when Driving Over Bumps (Diagnose/Repair Procedure)
Models:
1994-97 Cadillac Concours, DeVille, Eldorado, Seville
with 4.9L or 4.6L Engine (VINs B, Y, 9 - RPOs L26, LD8, L37)
This bulletin is being revised to add the 1997 model year and to update parts information. Please discard Corporate Bulletin Number 53-33-04A (Section 3 - Steering/Suspension).
Condition
Some owners may comment on a clunk, rattle, or loose lumber noise from the front of the vehicle when driving over small bumps at low speeds.
Cause
This condition may be due to a number of different sources. These include, but are not limited to:
^ loose strut mounting bolts,
^ loose stabilizer bar link pivots,
^ coil spring clash (1995 DeVille only),
^ noisy front upper strut mounts,
^ noisy engine mount.
The use of Kent-Moore tool J 39570, ChassisEAR, is recommended when attempting to identify the source of the rattle. It is IMPORTANT to note:
^ Properly functioning cars WILL transfer noise to the ChassisEAR.
^ If not familiar with noise from a known good car, comparison MUST be made between a "good" car and the car to be evaluated.
Correction
The following corrections only address the sources listed above. Other sources are possible and may require attention not outlined here.
1. Check the strut mounting bolt fasteners for proper torque:
^ upper (to body): 24 N.m (18 lb ft)
^ lower (to knuckle): 170 N.m (125 lb ft)
^ damper shaft nut: 75 N.m (55 lb ft)
Notice:
Do not over-torque damper shaft nut as it could damage the upper strut mount.
Check torque of stabilizer bar link attachment points:
^ 1994: 65 Nm (48 lb ft)
^ 1995-97: 55 Nm (40 lb ft)
Notice:
Do not allow the ball stud to rotate during tightening of the nuts or the link may be damaged.
2. If the torque is correct in Step 1, disconnect stabilizer bar links and determine if noise is gone. If it is, replace the stabilizer bar links.
^ 1994 link: P/N 3523593
^ 1995-97 link: P/N 3530406
3. Some 1995 DeVilles may exhibit a condition known as "spring clash". This is a metallic clunk noise from the front of the vehicle. This spring noise is due to low spring load allowing the first inner spring coil to "clash" against the second coil during compression. To correct this condition, install coil spring, P/N 22132857 (one or both). This is a redesigned spring and meets trim height specification. THIS SPRING IS FOR VEHICLES BUILT UP TO AND INCLUDING VIN SU266448. VEHICLES BUILT AFTER THIS VIN ALREADY HAVE THE REDESIGNED SPRING INSTALLED.
4. A loose lumber noise may be heard by driving at speeds typically between 10 - 45 mph over both smaller sharp bumps and larger bumps (more prevalent on small sharp bumps). Replace the front upper strut mounts with P/N's 22178707 (for all 1994-96 models and 1997 DeVille, Eldorado) and 22178708 (for 1997 Concours, Eldorado ETC, Seville).
Important:
To distinguish between Steps 4 and 5, use the ChassisEAR J 39570 and attach clips to the front engine mount and upper strut mount/shock tower area. Please note:
^ Noise will be heard if ChassisEAR is attached to the strut. You will need to familiarize yourself to a non-complaint car. Normal operating sounds may lead you to service a good car.
^ More noise will be heard if ChassisEar is attached to the strut rod top nut than to one of the three strut mount fasteners in the strut tower. You will hear strut operating noises in the nut, while the noise heard in the strut mount fasteners will be more quiet since the job of the strut mount is to dampen. Any noise heard from the strut rod is likely normal; strut replacement will NOT affect this noise. To verify, compare to a known good car.
^ Assure that ChassisEar clips are securely affixed. Any movement of the clips to the fastening point may result in false noise being generated.
^ Do not test drive the vehicle with the hood open to the secondary latch as the hood movement can make false noise. Latch the hood fully.
5. If the lumber noise is produced at speeds only below 20 mph while driving over a larger bump, then it may be engine mount related. This noise sounds as if it is coming from the middle to under dash area, while Step 4 sounds as if it is coming from above the dash. On vehicles equipped with a 4.6L engine, replace the left engine mount and the right transaxle mount. On vehicles equipped with a 4.9L engine, replace the left engine mount only.
^ 4.6L left engine mount: P/N 22171688
^ 4.6L right transaxle mount: P/N 22171682
^ 4.9L left engine mount: P/N 22171683
Parts Information
Parts are currently available from GMSPO.
Warranty Information
For vehicles repaired under warranty, use the table.