Advice needed RE: cooling system on a 93 Camry
 

The vehicle in question is a 93 Camry, 4cyl.

- Radiator recently sprung a leak and was replaced and the coolant was bled at the same time (obviously). Rad cap was not replaced at the time.
- Started overheating today, temp gauge creeps up to the red some time after the engine has warmed up, white smoke coming from radiator
- Electric fans do not turn on despite the rising temperatures, only activated when A/C is on. Cools down back to normal once the fans are running and the heater is running
- Replaced rad cap, same symptoms

Faulty thermostat?

If the fans aren't coming on you need to see if the temp sensor/switch is working properly.

And it's always best to replace the thermostat/rad cap when doing a major job like a radiator (unless the t'stat is a bitch to do or expensive). Kinda like doing the water pump when you do a timing belt - they just go hand-in-hand.

I'm not sure on the specifics but the reason the t-stat wasn't changed at the time of the rad job is that I was operating under the assumption that it was done at the same time as the timing belt/water pump 40k ago. Who knows...

electric fan switch is plugged onto the thermostat housing....check if the pins are broken and just replace it anyway it's like a 15 bux part.

T-Stats do fail prematurely. Your thermocouple switch is fucked too, by the sounds of it or fan relay or possibly fan. Meaning have the fan and related electronics checked.

easy way to test it is to find your single wire fan switch, and unplug it with the ignition on, while the engine is NOT running... if the fan spins up while you unplug the switch, the switch is faulty...

ps.. thermostats are EASY to replace on that car...
drain coolant
find lower radiator hose and trace it to the engine
undo 2 10mm nuts that are on the housing at the end of that hose
replace thermostat.. buy a genuine toyota part!!
tstat 90916-03090
gasket 16325-63011
coolant C0009-00119
make sure when installing the new thermostat, the little air passage nipple is on the top when you put it in...
bolt it snug, but not too tight
fill coolant and start engine, turn heat to max, turn climate control fan off...
let engine idle/high idle until the electric fan turns on and then off... twice...
reinstall radiator cap

when you fill and bleed coolant in a car with an electric fan, you're supposed to fill and bleed coolant until the electric fan comes on and off by itself twice... then put the cap back on... whoever replaced your radiator and bled your coolant obviously did not do this... also, you're supposed to have the heat on max, with the climate control fan off...

Disconnected the fan switch and with the ignition on, fan is on as well. So the t-stat is at fault then? Or the fan switch sensor?

And for the record, I did all the work, lol. I've only ever done the rad on my 240 so I had no idea about the electric fan thing but I know now!

so if the fan turns on when your ignition is on, and your fan is unplugged, but when you plug it back in, the fan does not turn on, i suggest you try replacing the thermostat...

check your spark plugs too... a blown headgasket will cause overheating as well... and usually, the spark plugs on cylinders 3 and/or 4 will look whiter than the plugs on cylinders 1 and 2...

one other thing, if you jack the nose of the car up, and bleed coolant with the radiator as high as you can get it, usually, it bleeds easier and much more thoroughly...

also, when your car is "overheating" check to see if both your lower and upper radiator hoses are hot... also check the lower portion of the radiator to see if its hot... if the whole radiator and both upper and lower hoses are hot (should be waaay too hot to touch) then likely, your fan switch has failed...

if your car is "overheating" and your upper radiator hose is hot, but your lower hose is much cooler than the upper, then likely your thermostat has failed...

you can also remove the thermostat, take the gasket off the thermostat, and put it in a pot of water and boil it.. you should see it physically open when the water nears boiling temperatures...

edit

I have a '93 camry V6 and yesterday I idled for about 10 minutes and the engine started overheating. No engine oil left or water. Bubbling sounds were in the engine bay under the radiator fluid and a pool of fluid under the car, smelt like engine oil but I was unconfirmed as of now. Also a sour smell whenever I rev the engine a bit to test it.

Took the car to a shop and pumped in oil+water, runs ok now. I have no clue what the hell went wrong.