overflows antifreeze at stop lights

[bgtg]

my 1991 corolla overflows antifreeze when idling at red lights for a while. I dont hear the fan running anymore like it used to? the temp guage never shows hot but it smells like antifreeze when it idles. Is this the thermostat or is the electric fan shot? any help would be appreciated.

[90 GP]

Either the relay,sensor or fan itself could be bad. My gauge generally reads at the halfway point. If it rises above that the fan kicks on and stays on till gauge goes back to halfway. You could check fan by unplugging and do a direct hookup to see if it runs. Would also check thermostat.

[bcp477]

Your engine is overheating....do NOT drive it this way...park it until repaired. As for the temp indicator, the sensor is probably bad...and needs replacement. The fan sensor is also probably bad....and that is why the fan doesn't run. It could be the fan itself, but that is less likely. Finally, the thermostat could be bad as well.
The sensors and the thermostat are located in the same area....the water outlet, under the distributor. Replacement of these items is easily accomplished....and I'd STRONGLY recommend fixing this before driving the car again....lest you ruin your engine (that won't take long, with chronic overheating).

[Donald]

The easiest way to check the fan and fan relay, is to pull the plug on the fan switch on the thermostat housing, with the ignition switched on, the fan should run.

The fan switch connector is the one that points towards the battery, with only one pin inside it.

If the fan switch goes bad, the fan should run, it is a fail-safe-on system.

Note: The operative word there is should.
There is always the possibility that it does not work according to plan.

[bgtg]

ok I unplugged the fan relay with the switch on and the fan ran immediately.. So is it the relay or the thermostat or should i just replace both?

[Donald]

The fan running means that the fan and the relay are good.

I would next suspect the thermostat. I would say replace it just to be sure.
If that doesn't cure it, that I would suspect the fan switch.

I am curious though, about the temperature gauge not showing hot.
Does it move at all?

[bgtg]

yes, the guage goes about 1/4 way up and never shows much hotter than that... it has always run cool since i have it. where is the fan switch?

[Donald]

The fan switch is that sensor on the thermostat housing where you disconnected the wire.

If it is not getting hot, you might have a blown head gasket, and it is compression leaking into the water jacket that is pressurizing the cooling system.

[bcp477]

The car running cool all the time could well be that the thermostat is stuck OPEN. My sedan had exactly this condition, when I got it.....and the thermostat had probably never been changed.

This doesn't jibe with the overheating problem, though. If the thermostat is stuck open, the car should never overheat....even with idling for a good while. Try feeling the rad hoses, when the car is as hot as it ever gets. If both are relatively cool (one should be too hot to hold on to, if all were normal).....then the thermostat is stuck open. If so, then the coolant expulsion from the system isn't due to overheating.....perhaps the head gasket is blown.....as suggested by someone else.

[verlaryder]

If you want a normal running cooling system then it must be returned to original condition. That means using a 50/50 mix of toyota long life (red) antifreeze and distilled water, a toyota part$ 9061-03046 thermostat and toyota part$ 16325-63011 thermostat gasket and toyota part#16401-63010 radiator cap.

After installing these parts, temp gauge should be near the half way point most of the time and fan should kick on at long stoplights and no coolant should overflow under any circumstances.

[Flashmn]

If you want a normal running cooling system then it must be returned to original condition. That means using a 50/50 mix of toyota long life (red) antifreeze and distilled water

Original coolant for the AE92 is green coolant. Toyota started using the red stuff when their newer gen engines came out, which are all aluminum.

But a coolant and thermostat and cap change wont fix this problem if its something worse, which it sounds like. Trusting the guage on the dash isnt worth it, it doesnt show accurately and it totally stops working when theres air inside the block.

[verlaryder]

Originally Posted by Flashmn

Original coolant for the AE92 is green coolant. Toyota started using the red stuff when their newer gen engines came out, which are all aluminum.

But a coolant and thermostat and cap change wont fix this problem if its something worse, which it sounds like. Trusting the guage on the dash isnt worth it, it doesnt show accurately and it totally stops working when theres air inside the block.

Bgtg has a '91 Corolla. Toyota started filling all Corollas with Toyota Red beginning in 1988 when the engine blocks were cast iron. I rented and checked many of '88 Corollas in 1988 and verified they had the Red plus I bought a 4A-F '89 Station Wagon that was made in Nov.1988 and it had the Red.

A good working Toyota thermostat in conjunction with a Toyota radiator cap enables the cooling system to self bleed itself of trapped air. The Toyota thermostat's jiggle valve lets trapped air bleed out of the block and the radiator cap creates a vacuum when the engine is shut down so that coolant in the overflow bottle flows back into the radiator thus keeping it filled to the brim. Thus there can't be "air in the block" to begin with (except for a short time in the event the cooling system was improperly filled with coolant) if a good working and properly installed (jiggle valve near the 12 noon position) Toyota thermostat (and Toyota thermostat gasket) and radiator cap are used and the owner keeps the coolant overflow jar filled half full of coolant.

[Flashmn]

Bgtg has a '91 Corolla. Toyota started filling all Corollas with Toyota Red beginning in 1988 when the engine blocks were cast iron. I rented and checked many of '88 Corollas in 1988 and verified they had the Red plus I bought a 4A-F '89 Station Wagon that was made in Nov.1988 and it had the Red.

And they still have the original coolant in them?

I cant really say, I was under 10 back in 1988, but most older toyotas I've seen here have had green in them, even my AE92 had green in it when I bought it 10 years ago.

Yeah a good working thermostat and radiator cap do help in cooling, but I doubt this is the case in the OP's car and it doesnt have to be Toyota to work. There CAN be air in the block even if the systems are set correctly, I had a water lock in my bypass line in my corolla, which caused boiling of water. Maybe you should give advice to the OP on his car, not just spout off part numbers and tell him to get parts for his car, which he might not need. Sounds like to me

[bcp477]

Alright....enough dammit. Can we all not let this devolve into some bloody stupid argument about the freaking colour of the coolant....or which part #'s someone favors ? There are plenty of good parts out there, whether Toyota- branded, or not. Coolant with a colour other than red WILL work in the car.

The OP needs now to do some checking, based on suggestions already made....and get back to us on the results. THEN, once we have more information....we can make some intelligent judgements and further suggestions, if needed.

[Flashmn]

What he needs to do first is find a shop that can check if theres CO (carbon monoxide) emissions going to his coolant. That would rule out or tell if its the headgasket thats gone.

A broken waterpump can do this aswell, coolant not circulating is a problem. Do the hoses feel hot on top and warm/hot on the bottom or hot on top and cool in the bottom. Latter indicates theres no water flow going on, which could mean a broken waterpump.