Problems with hot starting were identified in the late 70's. GM developed an improved solenoid to reduce the problem. I have not had hot start problems but my starter is years old and I had it out to do engine work. I replaced the solenoid with the improved version.



complete starter:



If you have it out, count the teeth. If you need replacement someday it is good to know. (Usually 9 or 10, 9 on mine.)

There is a combination nut/Belleville washer for the solenoid winding nut that maintains tension even when the stud grows with heat (the main cause of hot start problems). Search this site for Belleville to find the number.

Be sure the starter bolts are the OEM shouldered ones for proper locating. A ground wire from battery to a starter bolt can help, too.

Thanks for the comment, Bill. My old solenoid had the Belleville washer and I forgot to remark and include it in the photo. (It's still in the can with the other bolts, etc.)