I have a couple of issues with my 92 LT1 6 SPD I need help figuring out. When I drive the car for any significant amount of time/distance (usually at least to it gets up into normal operating temps), and I stop and turn of the car, when I try to restart it, it won't turn over. I suspected the starter has been experiencing heat soak issues.

(1) The starter is relatively new with few miles
(2) The CATS was replaced a couple of years ago.
(3) I currently have a H65 trouble code that pops up

I wrapped the starter with heat shielding material but that does not seem to help. After letting the car sit for a few hours and tapping it with a hammer, it would turn over. Should I start by buying a new starter? Would a bad CAT cause the O2 sensor and the starter to have issues? What do you guys advise?

 

It's not your cat or O2 sensor - they aren't related to the cranking performance of your starter system. First thing I'd do is remove the battery terminals and clean them well, and then put them back on and make sure they are really snug. Then, make sure the other end of each cable is also clean and snug. It's possible your starter or battery are getting to their end of life, but it's equally possible the connections just aren't good. I don't know for sure if the cat replacement on a stock LT1 entails removing the starter, but it's a good bet that it did. So there's a reasonable chance that the battery cable that connects to it isn't snug/clean. I though my starter was going south last fall, because it would crank slower and slower the hotter the engine got. Turns out that just cleaning and reattaching the cables at the battery terminals solved the problem.

If you car is literally not even trying to crank when hot, you may indeed be experiencing a problem with the solenoid getting stuck open when hot. Does ever stick closed, such that you crank the engine, then let off the key, but it keeps cranking? If so, that solenoid on the starter is the likely cause.

 

Have battery tested and check connections. Some parts store will test starters and alternators for free. I would have them tested before buying new one.

 

If tapping it with a hammer will get it to crank then its virtually certain the starter is bad.