2003 Toyota Corolla



January, 29, 2009 AT 6:27 AM

Engine Cooling problem
2003 Toyota Corolla 4 cyl Front Wheel Drive Automatic 93000 miles


I am having a problem with the cooling system and am trying to pinpoint what's wrong with it. Both my heater and air conditioner stopped working. I checked my coolant level and it was empty in both the radiator and overflow tank. So, I added some antifreeze in both places. I then noticed the antifreeze in the overflow tank was drawn into the radiator and the overflow tank was left for empty. The heater started working for a few days, but then stopped again, I assume because the radiator itself ended up loosing all its coolant too. My air conditioner still isn't working. I felt the larger evaporator outlet tube with the air conditioner on full blast, but it was warm, which if I understand correctly means I don't have refrigerant running through the system. I then added some more antifreeze to the radiator cap and let the car run. Well, the heater obviously began working again once I added the antifreeze, and the air conditioner, not to my surprise, still wasn't working. I felt the upper hose and it was hot, but the lower hose was cold. I looked underneath the car and could see coolant had begun to leak. I could see dribbles of bright red coolant on part of my radiator too. Also, I noticed the radiator fan wasn't running even with the engine warmed up and a/c turned on full blast. The two tubes that are connected to the heater core were both hot.

So, my questions are:

1.) First off, I am wondering the exact route the coolant flows. After pouring it in the radiator cap, where does it immediately go next and how does the rest of the flow go?

2.) If the engine has been running and is up to normal operating temperature, is the radiator fan always supposed to be running at that point? Mine was not running, but I do not know if once the engine is warmed up whether or not it is always supposed to run.

3.) I am pretty sure I have a radiator leak since it is coming out underneath the bottom of the car and I can see bright red coolant dripping from part of the radiator. But I am wondering how can the coolant get to my heater, yet from what I gather it is not getting to the lower radiator hose (since the hose is cold there)? Also when I press the lower hose, it's like I can feel a little liquid in there sludging around, but the hose is not hot at all. I don't know if that means something is wrong with the hose itself or if that's a result of the radiator leak (if I do have a leak)?
The thing that confuses me is I read on one of your responses that if coolant goes from the overflow tank to the radiator that means a vacuum was created and you can't have a leak, but I am almost certain there must be a leak.

4.) Does the coolant and the refrigerant run through the same tube in the radiator or through two different tubes? I seem to be losing both coolant and refrigerant from what I gather.

5.) Is it safe to rule out the water pump, thermostat, leak plugs, coolant temperature sensor, and heater core with the information I have given?

6.) If I do have a radiator leak like I am assuming, would you recommend something like a stop leak tablet? Or is this something I need to bring in to the shop?

7.) Also, I checked my transmission fluid two months ago and it was pretty much red for the most part with perhaps a little bit brown to it. But now two months later I've checked it and it is almost completely brown and dirty. What has made it get like this?

I hope you guys can answer all these questions or at least some of them. Thanks a lot for your help.


P.S. I was going to give a donation, but a warning comes up saying the website certificate has expired.


3 Answers



January, 29, 2009 AT 9:09 AM

The AC and coolant are two seperate problems.

First problem is coolant. If you have a coolant leak, don't assume anything, have it pressure tested and find and fix the leak. Flush and refill the system with Toyota Red.
Coolant is circulated through engine and heater core, when thermostat opens it flows through radiator. You would have heat as soon a engine warms, since heater core coolant is not dependant on thermostat.

The fan should turn on (at slower speed) when AC is commanded.
The fan should run when engine exceeds about 220 degrees (give or take), but if there is no coolant in the system the coolant fan switch will not work.

This is an Aluminum engine and is very sensitive to overheating, get the cooling system fixed ASAP.

DO NOT use stop leak, if radiator is bad, replace it.

AC system should be checked by professional shop, you can go without AC for a while, but cooling system failure will cause major damage.

Have trans fluid changed ASAP, trans. Fluid is routed to radiator and cooled in a closed and seperate system withing the radiator, if this has ruptured, you could get coolant in trans. And ruin trans.



January, 29, 2009 AT 12:23 PM

Wow, you are good.

So, I brought it in this morning. They did a pressure test on it and said it's a radiator leak and that's it's cheaper to just buy a new radiator than to send it off to get repaired. I am just thinking of throwing some Bar's stop leak into it since I know it is just a leak now. That's what my neighbor suggested I do.
Otherwise they want $333 for a new radiator. He also suggested I get a new thermostat because since I have been running it under constant stress the thermostat could easily close soon and I would need to get the whole radiator flushed again I think he said. Idk what to do. Dish out the big bucks? Or, throw in a few dollars of Bar's?



January, 29, 2009 AT 9:38 PM

Well it's your money, but I would replace the radiator and thermostat (use Toyota part for thermostat).

As I said, the 1ZZFE 1.8 Toyota engine is an all aluminum engine. Even one serious overheating event can damage the engine to the tune of thousands of dollars.

But as I said, it is easy to spend your money : ).

Whatever you do, DO NOT let it overheat, and if coolant is leaking you cannot trust the temp gauge, since if it is not in contact with coolant, it will not give an accurate reading.

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