I've got a bone stock 1990 Civic Hatchback Base (D15B1 and 4 Speed Manual) with ≈250k miles. In November of '24 I broke a timing belt 2. When I pulled the factory PM3 head off of it I found that the exhaust valves on cylinder 2 were each missing approximately 1/3 of the valve face. I replaced the head with a remanned unit (PM9) from Cylinder Heads International. Fast forward to last week when I had a heater hose burst at 80 on the interstate and overheated it. Had white smoke rolling out the exhaust by the time I got her home. I pulled the head off of it to replace the head gasket. I found that once again on a completely different head, the cylinder 2 exhaust valves are getting cooked. What do you think is causing this? And how do I fix it? For added context I'm relatively confident my rings are shot because she still burns about 1/2 quart of oil a week with the newer head and was burning a full quart a week before the head replacement. Also this is my daily and I commute roughly 6-8 hours a week with it, 70/30 Highway and City.

 

Could be a coincidence if you blew the head gasket and things got really hot right there?

Or since you know your rings are “shot” maybe that cylinder is burning more oil than the others. Or a fuel injector could be hanging open - assuming all those parts have stayed the same since 2024.

 

I'd be sus on injectors

 

You answered your own question, "I'm relatively confident my rings are shot because she still burns about 1/2 quart of oil a week with the newer head and was burning a full quart a week before the head replacement." Did you do a compression and leakdown test on the engine after you replaced the head? All that oil blowing past the rings goes into the combustion chamber and causes all kinds of problems with contaminants caking up valves and dirty running conditions for the engine.