Engine - Rythmic Rattle/Knock Noise at Idle

BULLETIN NUMBER:
SB97-01-L001

ISSUE DATE:
APRIL 1997

GROUP:
ENGINE

1997 HOMBRE (TH) 4.3L V6 ENGINE NOISE AT IDLE

AFFECTED VEHICLES

1997 Hombre (TH) models equipped with 4.3L V6 engine.

SERVICE PROCEDURE

Some affected vehicles may experience a rhythmic engine noise at idle. This noise, which occurs at half engine speed, resembles the sound that a helicopter makes while idling (a "whoop-whoop" best describes it). This noise may also sound like an engine rattle, a lifter tick, a balance shaft noise, or a rod knock. When heard through a stethoscope, the noise appears to come from deep within the engine. The noise may also be heard in the passenger compartment, at the catalytic converter, and at the tail pipe. As the engine warms up, the noise grows louder.

The cause of this noise may be from a low level of lubrication on the exhaust valve stem, which creates a "slip-stick" condition between the valve stem and the valve guide.

To repair this condition, replace the valve stem oil seals on all exhaust valve guides with new valve stem oil seals (Part No. 8-00460-483-0) and replace the two valve rocker arm cover gaskets (Part No. 8-10201-397-0), using the procedure described in this Service Bulletin.





Replace the valve stem oil seals on all exhaust valve guides with new valve stem oil seals (Part No. 8-00460-483-0) and replace the two valve rocker arm cover gaskets (Part No. 8-10201-397-0). Refer to Figure 1 in this Service Bulletin and to pages 6-195 through 198 of the 1997 Hombre (TH) Workshop Manual Book 2 (TH097-WSM-L01) for replacement procedure details.

IMPORTANT!
Do not install this valve stem oil seal on the intake valve guides. This valve stem oil seal is not designed for intake valve application on these affected vehicles.

PARTS INFORMATION

Part No. Description Qty Required

8-00460-483-0 Valve Stem Oil Seal 6
8-10201-397-0 Valve Rocker Arm 2
Cover Gasket

WARRANTY INFORMATION

Use published Flat Rate Manual labor operation number 01J0547 for valve stem oil seal replacement. Refer to page TH-01-03 of the 1997 Hombre (TH) Flat Rate Manual (TH097-FRM-L01) for details.

Labor operation number 01J0547 includes replacement of valve rocker arm cover gaskets.