My 2008 Prius with 125k miles is running fine but is pressurizing the cooling system after a prolonged overheating event where the belt snapped. The fluid color radiator test shows bad head gasket (fluid turned green). Looking for advise on what to do while replacing the head gasket. Planning to grab the Mahle or Felpro gasket set and doing to work myself. I can lap/flatten the head at my job if there is any warp. Do you think it is likely that there would be a crack in the head? I'm trying to save some cash with everything else I have going on. To have the head pressure tested and resurfaced is about $200. Another $250-300 for valve job if needed. A rebuilt head online, shipped is about $615. Another $200 for the gasket set, water pump, thermostat, etc. What do you think is my best option: $200 for gasket set, water pump, and thermostat. Lap my head and hope for the best with no cracks in head. $500-800 for rebuilding my head and gasket/pump/thermostat. If it's cracked, I need option 3 anyway.. $815 for rebuilt head gasket/pump/thermostat.
I relatively recently replaced the gasket on a 2009 and I FAILED (coolant still leaks into oil). One thing I would do differently is take the head to a shop for resurfacing. I got quoted "about $60-70". I personally would not buy a refurbished head unless it comes with both cams, otherwise getting correct valve clearance could become an expensive hassle.
The head bolt socket is NOT triple-square nor XZN. It is dual hex aka bi-hex size 8mm and you need one that is longer than a typical bit. Performance Tool W83184 Extra-Long Double Hex Head Bolt Sockets for Toyota Engines, 2 Piece, 8mm and 10mm Sizes, S2 Steel worked great. $18 regular price from Walmart. It was shipped, I don't think stores carry it, but I'm not sure. I used the Felpro the 1st time. The gasket looked good and I don't suspect the gasket at all. This time I ordered a Mahle for no other reason than that it shipped from the same Rockauto warehouse as stuff for other vehicles. The Mahle seemed to resemble the head gasket that was on the car (I don't know if factory original) more in some details, but I have not compared. I don't suspect that the gasket had anything to do with what went wrong. The timing chain cover has a water passage, so pay attention to get sealant everywhere it's supposed to go. I didn't touch the inverter other than set the inverter tank aside. Moving the inverter housing would have made accessing stuff on that end of the head a bit easier but was not necessary. 90 degree pliers helped with hose clamps.
I have had my 2009 about 60k miles and I'm not aware of any overheating during my ownership. (Only unusual engine issue I had was intermittent misfire caused by a faulty NGK spark plug from rockauto, so not supposed to be a fake like one can supposedly easily get from ebay, amamazon, etc). I plan to definitely check the head much more carefully for cracks, because I felt that the procedure went well but it didn't fix the problem. My cooling system holds 15 psi for days, but as soon as combustion forces are present, coolant mixes into oil, even on a completely cold engine, so coolant is not yet at anywhere near radiator cap pressure.
You should be able to get a one NZ head w cams valves adjusted and set etc about 400. I did same w 1zz the guy said he could 1nz for Prius . He did a bang-up job on the ones easy look like a brand new head and I'm sure the Prius will be saying that was delivered .!
