What causes 1991 toyota camry to over heat? we put a new radiator in it last year cause the radiator got cracked. but it didnt start overheating til this year. so we changed the thermostat thinking it wouldnt do it anymore. it kept overheating so we changed the thermostat again but it wasnt it so we changed the water pump. it still keeps over heating. an we cant figure out why. if we keep the car running when its parked its fine. but once we start driving it it overheats an steams after 10 minutes an overflow is boiling because steam is coming out of the hose from the radiator.

yes your car will be over heat, just go to junk yard and open thermorstar sensor of another car to replace the old one that is cheap than you buy a new one ok!

A seal (gasket) failure is one possible cause. Or possibly a cracked intake manifold or even a cracked block. Warping from overheating is a another possibility. Engine will need to be disassembled to determine cause. It's not all doom and gloom. A cylinder compression check may provide you with enough information to see if it is worth attempting a repair before getting into an engine teardown. If it's a top end engine repair, it won't be cheap, but may be worth your while...the key is to understand what caused the engine failure before sinking any serious cash into a 23 year old car.

look close on the top of the radiator they crack there. and the other thing you can do is put a piece of card board under the front and run the car and see where it leaks

You may have

- a coolant leak somewhere, comes out when the engine heats up and pressurises the radiator. Camrys do develop a crack in the plastic radiator top tank, which can be hard to see if on a seam. Another place which leaks is under the intake manifold, which is not visible. There is a test, called a "leak-down" test

- thermostat stuck closed, preventing coolant circulation

- a leak through a head gasket from a combustion chamber to the coolant jacket. This will quickly cause overheating, and sometimes causes white bubbles in the radiator neck, like dry ice. There is a test kit available for gases in the coolant.

check oil make sure is not milky ,is it bubbling in reservoir cause the only thing that can cause it is a blown head gaskek

did you unclip the topmost hose when engine hot to get rid of any air.....?

I assume the engine is running correctly.

First make sure the coolant is full and has no leaks.
If you are not sure about leaks , it can be pressure tested. The pressure test may also tell if the head gasket is good.

Replace the thermostat and coolant. Check the fins in the radiator core are not corroded

If it still overheats, you may need a radiator replacement. radiators often only last 8-10 years

Dont drive it overheating, as it will damage the engine and cause it to burn oil and smoke

You may have a clogged radiator or you didnt get all the air out when you filled up the coolant
Its also possible the water pump fan blades are corroded away.
If anyone ever used a stop leak this could cause a blockage anywhere

the a/c when running creates a lot of extra heat and needs second fan, if second fan is not working right this will cause overheating, if fan is creating a load noise it is likely bearing is bad and will not spin as fast as it should not cooling. also check that fan it not hitting anything if you describe loud noise i can give better idea

The radiator is now plugged up, replace it before the overheating causes engine damage.