overheating, I'm stumped. Options

[6strngs]

so today, I drive my car home from work. get out of the car and notice a strong coolant smell. I let it cool down for a while, then went out to check it. The radiator was still full with coolant, but the overflow tank was kinda low. so I poured some coolant in (pre-mixed 50/50). anyway, so I go to drive the car again and after a short trip, only a couple miles, I'm hearing this weird whining sound. I glance down and see that the water temp gauge is reading HOT! like, it was all the way into the red! I pull into the closest parking spot and shut off the car. I let it sit for about half an hour and decide to drive it back home. I start the car up, and the temp gauge jumps to 1/2 way. normal. and as I start driving, it starts climbing. it gets to about 3/4 of the way to hot and then very suddenly just drops back down to half. then it stays there the rest of the way home. I pull into my garage, and get to work. I tried my best to track down a leak and decided it appeared to be that the hose that feeds coolant to the throttle body was leaking. so I replaced it. so after a couple hours of work (decided to do some other stuff too since I had everything taken off anyway) I go to drive it again and same thing. the temp gauge reads normal, then it will climb in temperature, then drop back down to normal, then climb again, then normal. anybody have any ideas? thermostat? water pump? malfunctioning sensor and/or gauge?

[6strngs]

alrighty. so I get out there, drain the coolant (after spilling a bunch all over myself and the floor) pull the hose off the thermostat housing, pull one nut off the housing, and cannot for the life of me get the other nut off! in my hayne's manual it says in some fine print "on 5sfe engines the retaining nuts may be difficult to access" wow, now that's an understatement! I tried every tool imagineable to get it off, nothing worked, until finally I found an extremely small wrench that fits in there after I removed the oil filter. of course, after trying all the other tools the corners of the nut are now mostly rounded off and I cannot get a grip on it at all. so basically I'm stuck.

btw, when I pulled the radiator cap off I noticed it was NOT full with coolant. I checked it yesterday and I'm pretty sure that it was full.

another problem. all across the bottom of my radiator is traces of leaks. I can't say for sure, but my brand new-ish koyo radiator may have a poor weld across the bottom.

I'm tired of having something break on this car every few days. aren't toyota's supposed to be reliable?

[Manny]

alrighty. so I get out there, drain the coolant (after spilling a bunch all over myself and the floor) pull the hose off the thermostat housing, pull one nut off the housing, and cannot for the life of me get the other nut off! in my hayne's manual it says in some fine print "on 5sfe engines the retaining nuts may be difficult to access" wow, now that's an understatement! I tried every tool imagineable to get it off, nothing worked, until finally I found an extremely small wrench that fits in there after I removed the oil filter. of course, after trying all the other tools the corners of the nut are now mostly rounded off and I cannot get a grip on it at all. so basically I'm stuck.

btw, when I pulled the radiator cap off I noticed it was NOT full with coolant. I checked it yesterday and I'm pretty sure that it was full.

another problem. all across the bottom of my radiator is traces of leaks. I can't say for sure, but my brand new-ish koyo radiator may have a poor weld across the bottom.

I'm tired of having something break on this car every few days. aren't toyota's supposed to be reliable?

Did you notice the traces of coolant on the radiator after you spilled coolant? it might just be dripping down the sides and collecting on te bottom. I think 94GT might be right though... make sure its topped off.... fill it up and wait for the level to go down then do the same thing over again.