Hello NC4176, Toyota actually had an issue with the 2az four cylinder head bolts pulling out of the block, usually from the back side of the head. The reason you might never see a coolant leak there is because underneath the intake plenum sits a large piece of foam that will act as a sponge absorbing most of the coolant that leaks out. This problem was in the first generation of that engine 2002 thru 2006. When this does occur the head will literally pull away from the block. May result in misfire, I have seen this with coolant and or oil streaming down the side of the block. There is a repair for this but is quiet costly due to the amount of labor involved. It involves tearing the engine down and drilling out the block threads and installing inserts into the block. If this is the case and you want to repair the car it may very well be more cost effective to price and install a used engine. Toyotech for 15 years and have seen this several times.
Friday, March 30th, 2018 AT 10:40 PM