ROCKER ARM SUPPORT MISALIGNMENT/REPLACE SUPPORT

MODELS AFFECTED: 1989 ALLANTES

Some 1989 Allantes may have been built with improperly machined rocker arm support bars. Refer to Figure 1. These vehicles are equipped with a forged steel support, P/N 1641338, rather than the cast aluminum support used on other 4.5L V-8 engines. A properly machined support bar is shown in Figure 2. Note that in the improperly machined bar, shown in Figure 1, the mounting holes for the rocker arm pivot are close to the edge of the bar. This causes the rocker arm pivot to hang over the edge of the support and can lead to cracks developing in the pivot at this point due to the unequal loading. The properly machined support, shown in Figure 2, provides enough machined surface to completely support the rocker pivot. Cracks in the rocker pivots may lead to eventual failure.

During other engine service work the rocker arm support bar should be inspected for this condition. If misalignment is indicated, the support should be replaced as well as all pivots on that side (PN's 1618819 and 1618820).

All parts are currently available from GMSPO.

WARRANTY INFORMATION VEHICLE SERIES --------------------- Operation --------------- Operation Description Number C D E J K V --------------------- ------ - - - - - - Arm and/or Pivot, Rocker-Replace Inc: R&R Rocker Arm Cover(s) One Cylinder Right Bank J0370 Left Bank J0371 Both Banks J0377

ADD:

A-To Replace All Arms and/or Pivots and/or Supports Right or Left Both

Part Group: 0.333 Policy: MT

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.