I will be going to the junkyard this week and get my fuel injectors .I figure while Im working in that areau , I might as well try to get those thermastat bolts loose again . The bolts that hold the metal thing down on top of the thermastat , (don't know what you call that thing ) are stuck . I can get the bolts to un-screw then they won't budge anymore .The bolts are rusted b/c its a re-built engine , plus I don't see any rust . How do I get these bolts out , and why are they stuck in there like that ? I took it to the shop awhile b/c it was over heating awhile back and I thought it was the thermastat , and the shop could not get them out either , but it ended up being the temp sending unit .Well I be able to get those bolts out if the shop was having trouble ? ..Thanx guys , Wayne

 

Its called a water neck.I dont know why you can unscrew the bolts and then they get stuck?HMMMMM makes me wonder.Especially you say theres no rust.

 

How bad do you want them out? you might have to snap them off, then drill and tap new threads, with the upper intake out of the way thats possible. try to tighten the bolts and then loosen, could try to gently tap them with a small hammer, apply some heat, that could warp the thermostat housing. if all that fails, another intake manifold, i've changed my thermostat a couple of times, the threads corrode, a hard white powder was on the bolts, galvinic corrosion. same kind of crap found on outboard motors. good luck