Catalytic Converter - Booming Noise at 1,500 RPM
Number: 84-125Section: 6F (VIII)
Date: May, 1984
Subject: 1500 RPM BOOM
Model and Year: 1982-84 CELEBRITY AND CITATION
VEHICLES EQUIPPED WITH LR8 ENGINE (INCLUDING 1984 CELEBRITY WAGONS)
TO: ALL CHEVROLET DEALERS
CONDITION
Some 1982-84 Celebrity and Citation vehicles equipped with the LR8 engine may exhibit a loud booming noise at 1500 rpm.
CAUSE
This condition may be caused by the catalytic converter hanger being preloaded.
CORRECTION
To correct this condition, the following procedures should be followed.
1. Remove the load from the catalytic converter exhaust hanger.
a. Loosen the converter and manifold flange joint bolts.
b. Break the converter joint loose.
c. Retighten the bolts to 20-40 N.m (15-30 ft. lbs.) while holding the converter up against the heat shield.
d. Make sure the distance between the upper and lower converter hanger rivets is less than 62 mm.
Cradle Dampener Assembly:
2. Install a newly released additional cradle dampener assembly (see illustration)..
P/N Description
22527158 Dampener Assembly
10021800 Bolt
Do not remove the existing dampener.