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2003 Acura TL overheating issue

Starting information: Car has 220k miles, temp hangs around the 3/4 mark on the gauge (normally it’s slightly below the middle mark). I test it by driving to work everyday, which is a 40 min drive on the highway going 65-70mph. It does reach the red mark or the H at times. Sometimes it stays normal temperature the whole drive, but that is very rare. The A/C does not work when it gets hot, it just blows warm air. Having no A/C on at all does not effect the temperature. Reducing speed when getting off the highway does reduce the temperature from H to 3/4, but it never goes to the middle mark or below. Driving non-highway speeds, it still does overheat. By overheating, I mean the gauge shows the temperature at the 3/4 mark or higher, it never smokes or breaks down.

Overheating first started about a month ago, mechanic said right fan was not working and to replace thermostat and coolant. I replaced the thermostat and added new coolant, the fan seemed to work properly, (would turn on when it started to get hot and stayed on), that did not fix it. I noticed the car was leaking coolant from the radiator and the reservoir, when I did an inspection the reservoir hose was spitting coolant back out, so I figured the radiator cap was faulty and couldn’t hold the pressure. Turns out it was, the cap was completely broken, so I replaced that and it seemed to work fine for a day. Now the car stays at the red line or H the whole way, even reducing speed to 40mph does not change the temperature. Checking the reservoir when the car gets this hot shows it is completely full (normally at the half way mark), so I’m going to replace the cap again since maybe it’s also broken and can’t hold the pressure. If that doesn’t work, I’m at a loss as what the problem/fix is and could use help.

I would pressure test the cooling system, if your mechanic has not done so, already.

I own a Stant kit that comes with everything needed, including complete instructions. If you don’t have access to such a tool then you could buy one or pay a mechanic to use her’s/his on your car.

That will give you a good starting point, if not solving this mystery for you.

Also, I’d use a non-contact infra-red thermometer and see how the temperatures at various locations are running.

Be advised, that at this age/mileage, a head gasket is one possibility.

I agree. You may have done damage to the engine running it in the red but with this mileage and unsure of the maintenance done, the culprits could be the radiator or water pump. Coolant needed to be replaced not just more added if that’s what you did, but that’s not the problem.

No one has pressure tested the cooling system, so I’ll look into getting that done and to get an infra-red thermometer. I am aware that driving when it first started having overheating issues could have caused damage to the engine. The car itself is old and having transmission issues so I don’t expect to get much more use out if it. Hopefully I can solve this mystery before it dies completely though, haha.

When the thermostat was replaced, all the coolant was drained and new coolant was added. I do agree with you though, that there could be damage done to the engine due to driving while overheating. I don’t know the maintenance done either, I’ve only had it for about 2 years and the transmission is starting to die, but I am hoping if I can fix the overheating for a cheap price so I can get a few more months out of it.

When the engine is cold, remove the radiator cap.

Start the engine and while the engine is idling watch the coolant in the radiator.

If bubbles begin to appear in the coolant, that’s an indication of a breached head gasket.


I would not drive this car any more. You have a overheating problem and if you keep ignoring the temp gauge and continue to run it overheating you Will do serious damage of you have not already.

This needs to be checked and the problem fixed or you could damage the engine beyond fixing. New engines are not cheap, even used ones from a bone yard.


I did that, no bubbles appeared.

Like I said, the car has 220k miles and the transmission is dying, along with many other problems. I am not going to invest a lot of money in this car, if the engine blows then it’s going in the junk yard.

If the transmission is dying, that could be what’s causing the overheating.

The transmission cooling lines go to a cooler in the radiator.

And if the transmission starts to run hot, the engine will start to overheat.


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I used to own a 1991 Acura Integra. I know completely different car. BUT, I once had a very similar overheating problem you are experiencing. The problem was a simple fix. When I had replaced the coolant, I didn’t “burp” the system of excess air. That excess air caused the cooling system to overheat, redline, and boil over.

You have to remember, the cooling system in all cars is pressurized via the water pump. When you leave air in the system, it’s not capable of cooling anything due to the “air bubble” you left in the system. Thankfully, the Integra motor had a “bleeding bolt” in the cylinder head that allowed bleeding off excess air from the system. BUT, you can also do it by removing the radiator cap, then grabbing the upper radiator hose and pulling it upwards, and squeezing it to remove the excess air out of the system. It seems to me that is your problem here.

You have excessive air in your cooling system that needs to be removed. It will not “remove itself” by just leaving off the radiator cap while the engine idles. Just do what I said: burp the system by manipulating the upper radiator hose with the cap off.