1968 Corvette: Service Bulletin: Inadequate Cooling
Subject: Inadequate Cooling
Model and Year: 1968 Corvette with 327 Cubic Inch Engine
Source: Chevrolet Service Technical Bulletin
Bulletin No: 68-T-13
Date: May 22, 1968
TO: ALL CHEVROLET DEALER
This bulletin is a supplement to Chevrolet Dealer Service Technical Bulletin 68-T-9.
Early 1968 Corvettes equipped with the 327 cu. in. engine may be subject to an engine overheating complaint.
The following changes have been made in production to provide improved cooling, effective with the serial numbers, as listed:
- Added slots in the valance panel and a panel extension, No. 3932933, to increase air flow to the radiator, effective with Serial No. S400720.
- A new fan clutch assembly, No 3857531, to raise the slip speed of the fan, effective with Serial No. S401344.
- New pulleys and drive belts installed to provide a higher numerical fan to water pump drive ratio, effective with Serial No. S412213.
If engine overheating is experienced on earlier units with the 327 cu. in. engine, the above corrections should be made as outlined on the following pages. Obviously, other conditions can be involved in overheating and should be considered along with the changes recommended in this bulletin.
Chevrolet Motor Division
General Motors Corporation
INADEQUATE COOLING - 1968 CORVETTE WITH 327 CUBIC INCH ENGINE
If engine overheating complaints are experienced, the following corrections should be made only on earlier units than those serial numbers indicated on page 1.
- Cut out cooling slots in valance panel using template attached to bulletin 68-T-9. Locate slots per template instructions. Touch up raw edges of slots with body color.
- Install lower valance panel extension, #3932933, using the extension as a template for drilling attaching holes.
- Install the new fan clutch assembly, #3857531, and the new pulleys and drive belts as outlined on the following charts:
On cars with L-79 and air conditioning (no power steering) it will be necessary to remove the water pump and water pump rear cover; and using an arbor press, push the water pump hub 1/8" further back on the water pump shaft. Be certain that the shaft is firmly supported on the press anvil to prevent damage to the bearing.