I just want to thank everybody for the tips on fixing a head gasket on 3rd gen Prius. all the information was extremely helpful and I did the job on my own in 5 days time. took a total of about 20 to 25 hours. I was very methodical about everything and even disassembled back a few bits after I had a hybrid error because my car was sitting for so long. but I got past all that and fired the car up and all is good in the hood. drove it about 500 Miles thus far and it's working like a charm. valves didn't need to be redone and cylinder head was straight still. again big thanks to everybody else who posted up on this topic.
basically everything in the gasket overall kit from Toyota. egr gasket, timing chain o rings, valve cover o rings, exhaust gasket, chain tensioner and gasket, airbox gasket, head bolts. more or less these items.
I use the Straight edge and a flashlight to see if it was warped at all. also a razor blade to see if I could stuff it in any spots underneath the straight edge but the engine never overheated so it was still flat. I did prop the cylinder head on the side and left gas submerged in the valve holes then scrub the valves to clean off any carbon. it's also a good way to tell if the valves need to be redone because the gas would leak profusely out. mine didn't need that.
The deed is done, but for anyone reading: a set of feeler gauges is cheap. Specs for flatness in the first head gasket link in my signature. flashlight is good idea though, to see where potential low spots are.
Just did a head gasket using dealer parts: Head gasket tube seals valve cover gasket. Ever since I did one of these repairs with an eBay gasket that lasted only 10,000 mi I worry whenever I do one even though I'm using a dealer gasket now with the super-seeded part number. This motor doesn't burn any oil
