ENG.BOOM/VIB 1300-1500 RPM NEW P/N BRACKET,BOLTS &PULLEY

MODELS AFFECTED; 1986 Brougham ("D") With 5.0L Engine (VIN Code Y)

NOTE: This bulletin supercedes the DCS message of February 20, 1986, which should be disregarded. This bulletin outlines current corrective procedures and part numbers.

Some 1986 Broughams with 5.0L engines may exhibit a phasing boom or vibration. The condition is most noticeable between 1300 - 1500 RPM at a frequency of approximately 80-100 HZ.

Cars with VIN numbers after #708330 require replacement of the following parts.

Quantity Part Name Part Number

1 Bracket - Gen. Rear (with Inetgral Spacer) 22535351 1 Bolt - Stud End (for 22535351) 22510585 1 Nut - For 22510585 271505 1 Belt - A/C Compressor 9433758 1 Brace - A/C Compressor - Rear 22535495 1 Bolt - (for Brace 22535495) 9440071

PROCEDURES

1. Remove the generator drive belt and reposition the generator to allow access to the second head bolt from the front on the left head (Figure 2, Item #4).

2. Remove the head bolt and replace it with the bolt (P/N 22510585) and torque to 169 N.m. or 125 ft. lbs.

3. Remove the nut and ground wire from the first position head bolt stud.

4. Position the rear generator bracket (P/N 22535351) over the head bolt studs. Reinstall the ground wire on top of the brace in the #1 head bolt position and reinstall the nut. Using the nut P/N 271505 at the 2nd position head bolt, secure the brace by torquing bolt nuts to 25 N.m. or 20 ft. lbs. (see Figure 2, item #4).

CAUTION:

Be sure to install the star washers over and under the terminal end of the cable to ensure a soiid ground connection.

5. Position the brace (Figure 2, Item 2) between the new bracket and the generator end frame and start the bolt just removed.

6. Remove all remaining accessory drive belts.

Beginning with VIN #708330, the water pump pulley and generator drive belt were changed in production to reduce the level of the disturbance. The part numbers of the new pulley and belt are:

New Number Old Number

Pulley 22505009 22532661 Belt 22524186 9433639

Cars with VIN numbers prior to 708330 may require replacement of these parts. If required, replace the original 7 inch water pump pulley with P/N 22505009, a 5 1/2 inch pulley.

7. Install all belts on pulleys. Be sure to use the two new belts.

NOTE: The new A/C compressor belt is one inch shorter, and is more easily installed by first passing it over the crank pulley behind the balancer, then crossing over the water pump pulley and placing it in the compressor pulley groove. From under the car slip the belt into the crank pulley groove from behind.

8. Using 323600 belt tension gage, tension all belts according to the specification chart (see Figure 5).

9. Remove the bolt at the manifold end of the brace attached to the A/C compressor bracket and loosen the bolt/screw at the end bracket (Figure 4, Item #11). Install the new brace P/N 22535495 (Figure 4, Item 10) on top of the existing brace at the manifold and start the new longer bolt P/N 9440071, but DO NOT tighten at this time.

Remove the pivot bolt (Figure 4, Item #5) and install the compressor end of brace P/N 22535495 an the bolt and reinstall. Install the nut and tighten all fasteners.

For warranty purposes use T6149 for 1.1 hours

Add for Replace Water Pump Pulley .2 hours Use T6157 for: Install Rear A/C Compressor Brace Only .3 hours

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.