G 20 Van V6-262 4.3L VIN Z (1993)
1992 LB4 VIN Z
For vehicles with "cold knock" only.
For vehicles with "cold knock" having previously installed detonation field fix PROM
-
OR -
For vehicles with "cold knock" and detonation
For 1991-93 model year L05 and L19, 1991 and 1993 LB4 engines, two actions have been found to show a high probability of success incuring short
duration cold knock (Category A). General Motors suggests performing the following steps.
NOTE:
These steps are only applicable to short duration cold knock, and will not eliminate a knock occurring under load. Neither will these actions eliminate a
knock lasting more than 10 seconds, nor a knock occurring in a hot or warm engine.
Step 1:
Install a check valve oil filter
Original Filter
Install
PF35
AC PF1218
PF51
AC PF52
Step 2:
Change the oil; use a synthetic oil meeting the API Service SG or SG/CE standard.
NOTE:
This action is only required once; conventional (non-synthetic) API Service SG or SG/CE oil may be reinstalled at the next oil change.
If an LB4 (VIN Z 4.3L V6) or an L05 (VIN K 5.7L V8) continues to exhibit short duration cold knock after performing steps one and two and