2003 - 2004 Corvette: GM TechLink: Coolant Leak at Cup Plugs

From GM TechLink, June 2004:

This information applies to 2003-04 Chevrolet and GMC C/K trucks, Cadillac Escalade, and Corvette, and 2004 Cadillac CTSV and Pontiac GTO with GEN III V8 engines.

If coolant appears to be leaking at the head cup plugs, clean the area and inspect for an actual leak, not a stain.

TIP: New engines may contain seal tabs, and it is possible for the plug to leak during the first 15 minutes of operation.

If the stain is cleaned and a leak is indicated, drain the coolant and install new coolant with 4 sealer tabs. Operate the vehicle for a minimum of 15 minutes to allow sealing, then re-evaluate.

If the cup plugs continue to leak after installing sealer tabs, install new cup plugs. Lower the coolant level so there is no coolant in the cylinder heads. Remove the cup plugs and clean the bores. When installing new cup plugs, apply Primer N (Loctite product number 7649) to the cup plug and Loctite 620 adhesive to the bore.

TIP: Applying to the separate substrates avoids any cross-contamination of adhesive and accelerator. This also prevents any potential pre-curing of adhesive that is applied to an activated surface.

Allow the vehicle to sit for a minimum of one hour before refilling and testing.

- Thanks to Sean Garrison