I have a '93 Grand Prix LE with a 3.1 v-6 engine. I am in the process of rebuilding the engine it has over 250,000 original miles on it. The engine never smoked or burned much oil but it did have an over heating problem it over heated so much that one of the pistons cracked from the top of the crown and the pieces lodged between the piston and cylinder head. The engine would not turn over so I decided to take the engine apart and rebuild it. I removed the two cylinder heads and took them to my local machine shop and asked them to rebuild the heads. After they rebuild the heads the machinist asked me if the engine ever had an over heating problem? I told him yes, why do you ask? He told me that the valve seats have a special coating put on them to prevent the valves from seizing up but when the engine over heats the coating burns off and leaves the valves vulnerable to seizing up when it over heats. I asked how long of a life do these heads have in this condition? He said, maybe a couple of months.
I find this hard to believe but does anyone know if this is really true? has anyone ever had this experience before? I would like your input on this subject please...
Thank you...
David Los Angeles, Ca.