Engine - Rythmic Noise When Idling
File In Section: 6 - EngineBulletin No.: 67-61-14B
Date: September, 1997
Subject:
Engine Noise (Install Valve Stem Oil Seal)
Models:
1994-96 Buick Road master
1994-96 Cadillac Fleetwood
1994-96 Chevrolet Caprice, Impala SS
with 4.3L, 5.7L V8 Engine (VINs W, P - RPOs L99, LT1)
1996-97 Chevrolet and GMC C/K, M/L, S/T; G, P and W4 Trucks
1996-97 Oldsmobile Bravada
with 4.3L V6 and 5.0L, 5.7L V8 Engine (VINs M, R, W, X - RPOS L30, L31, L35, LF6)
This bulletin is revised to include the W4 Truck Model for Chevrolet and GMC Trucks. Please discard Corporate Bulletin Number 67-61-14A (Section 6 - Engine).
Condition
Some owners may comment about a rhythmic engine noise at idle. The noise, which occurs at half engine speed, has been described as a "Whoop-Whoop" (similar to a helicopter idling), an engine rattle noise (not to be confused with PVC rattle), a lifter tick in the lower end, a balance shaft noise, or a rod knock.
When using a stethoscope, the noise will sound as coming from deep within the engine. The noise may be heard in the passenger compartment and in S/T vehicles is audible at the catalytic converter and tail pipe.
Important:
The noise will get louder as the engine warms up at idle.
The noise does NOT diminish with removal of the accessory drive belt, balance shaft gear, or disconnecting the torque converter.
Cause
The noise may be caused by a low level of lubrication on the exhaust valve stem, creating a "slip-stick" condition between the valve stem and valve guide.
Correction
1996 vehicles equipped with a 4.3L V6 engine (RPOs L35, LF6) should be checked to see if Campaign 96-C-17 (excessive oil consumption) applies and has been performed to the vehicle being serviced. Vehicles identified in the campaign should have the campaign performed before they are repaired for a "Whoop Noise" condition.
Install the valve stem oil seal listed below, ON THE EXHAUST VALVE GUIDES ONLY.
Lightly lubricate the seal, and with finger pressure only, push it on to the valve stem and down on to the exhaust valve guide. (See Figure 1)
Important:
DO NOT install this seal on intake valve guides. This seal is NOT released for intake valve application in the above identified vehicles.
New rocker cover gaskets may be required.
Parts Information
Parts are currently available from GMSPO.
Warranty Information
For vehicles repaired under warranty, use the table.