Water Pump - Impellor Update
Number: 84-49Section: 6B (VI)
Date: Jan., 1984
Subject: WATER PUMP WITH SHEET METAL IMPELLOR FOR 5.7L DIESEL ENGINES
Model and Year: 1978-84 IMPALA, CAPRICE, MALIBU, MONTE CARLO, EL CAMINO AND C-10 TRUCKS
TO: ALL CHEVROLET DEALERS
Water pump package number 556283 available from WDDGM, now contains a pump with a sheet metal impellor. This pump is also being used on production engines.
Dealer Technical Bulletin 81-T-40 defined criteria for the cast iron impellor. It must have square vanes and .045 inch clearance. It is no longer necessary to be concerned about this if a new pump with the sheet metal impellor is used.