my engine overheated in july 2013 but before then, my engine ran beautifully. Also, keyes in van nuys was given more than sufficient information about my engine's status, aside from the fact that i towed the vehicle into them and picked it up the same way. I specifically told them that coolant was found in the oil tank after the overheating. However, they started the engine anyway while running diagnostics procedures and lost compression in one of my cylinders, which rendered my engine completely destroyed. Gm corporate refused to assist in any way solely due to the amount of mileage on the vehicle, which was 140000 at the time of the overheat last year. They mentioned something about discussing it further if the vehicle was 130000 or less. Finally, they quoted me 8200+ for a new engine, but upon request, would not give me the technician's diagnostic report, or anything written by him. They said that they go by the honor system word-of-mouth of their mechanics for official diagnostics summation,.
the funny thing about this is that when i brought my car into keyes chevrolet, van nuys, and told him about it overheating, he immediately said that they had been getting a lot of 4.2l 6’s in for major problems. I bought a gm car because of its monster reputation for being built sturdy and lasting a long time. I can’t understand how an engine could be destroyed simply overheating for 5-10 minutes, long enough to get my car off the freeway. I kept up with it the entire time i’ve had it, faithfully changing oil, filters etc. I am the original owner of the vehicle too. All the sites I've been to discussing the 4.2 ltr engine have said things like engineering defects in the thermostat housing, fan clutch defects, intake manifold defects, head gasket defects, throttle body problems. But the most important thing I've noted is that some have had engine replacements only to find it still overheating afterwards.