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I flushed the radiator fluid on my TC 2000 3.8 (140k miles) using the recommended Prestone coolant.

The purpose was to resolve the engine overheating problem that occured each time the outside temperature was above 90F or when sitting in traffic for a while.

Since then I have identified 2 new issues:
- I can hear noise from the vents that the A/C normally makes when switching from outside air to recycle air... but this noise is repetitive, it seems each instance the A/C condenser kicks in.
- More annoyingly, I had filled the coolant liquid to the max line after having flushed the radiator fluid: the engine still overheats in heavy traffic after which I noted the coolant line sitting well above the max line, half way between the max line and the top of the coolant container.

I don't understand why my coolant level goes up after the engine overheats:
I had put the front vehicle on ramps after my last fluid flush and let the engine run until it reached its normal operating temperature, after which I switched the heating on to get rid of any air in the cooling system.

Any idea is welcome in helping solve this one. I am thinking of replacing the thermostat next, but I don't really want to add more changes before solving the cooling issues I have right now... Thank you.
 

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Welcome!

Since then I have identified 2 new issues:
- I can hear noise from the vents that the A/C normally makes when switching from outside air to recycle air... but this noise is repetitive, it seems each instance the A/C condenser kicks in.
Is this the same noise that you would hear if you manually switched from outside to recycle air yourself, like a clicking/door sliding noise?

- More annoyingly, I had filled the coolant liquid to the max line after having flushed the radiator fluid: the engine still overheats in heavy traffic after which I noted the coolant line sitting well above the max line, half way between the max line and the top of the coolant container.

I don't understand why my coolant level goes up after the engine overheats
It's physics at work. The coolant expands in volume when the temperature rises. The system can only hold a fixed volume of coolant, so the overflow goes into the bottle.

Question: Do you notice that the coolant level in the bottle is lower (back to normal) when the engine has cooled off for a while (like overnight...)?
 

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Discussion Starter #3
Welcome!



Is this the same noise that you would hear if you manually switched from outside to recycle air yourself, like a clicking/door sliding noise?

It's physics at work. The coolant expands in volume when the temperature rises. The system can only hold a fixed volume of coolant, so the overflow goes into the bottle.

Question: Do you notice that the coolant level in the bottle is lower (back to normal) when the engine has cooled off for a while (like overnight...)?
Yes, this is the same noise as if I had manually switched from outside to recycle air myself. :ask_wsign

Yes, the coolant in the bottle resumes to normal level on my following use of the vehicle if my trip does not make the engine overheat. :cool:
 

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Yes, the coolant in the bottle resumes to normal level on my following use of the vehicle if my trip does not make the engine overheat.
The one good thing about that is that it usually means that you do not have an internal leak or head gasket problems. If you had a headgasket problem, it usually draws the coolant into the cylinder, thus you lose fluid and have to constantly fill the tank, or the internal leak does not allow the system to be sealed and will not draw the fluid back into the system when the system cools down.
Hope you find your problem.
 

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Change your THERMOSTAT... that controls the temperature rise and fall in the engine. It is an inexpensive part, and should cure your problem. I am surprized that no one has mentioned this yet! :eek:
 

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The one good thing about that is that it usually means that you do not have an internal leak or head gasket problems. If you had a headgasket problem, it usually draws the coolant into the cylinder, thus you lose fluid and have to constantly fill the tank, or the internal leak does not allow the system to be sealed and will not draw the fluid back into the system when the system cools down.
Hope you find your problem.
Agreed, I don't loose any coolant, but I will be driving to Florida next month and I would like to pre-empt any issue with the overheating engine a thousand mile from home! :Wow1:

A little more on recent fixes I have made to the car, in addition to the radiator coolant flush:
- replaced the original transmission oil cooler with a bigger one and replaced transmission cooler hoses
- replaced the radiator fan assembly with a new one as one fan was not working on the original assembly

So technically, it should all be working... yet the engine still overheats and the A/C does this ongoing outgoing/recycle noise... :confused:
 

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Discussion Starter #7
Change your THERMOSTAT... that controls the temperature rise and fall in the engine. It is an inexpensive part, and should cure your problem. I am surprized that no one has mentioned this yet! :eek:
Yes, this was my next planned move, so I may grab a fail safe one from an autopart place today and install it... I'll keep you posted on how it goes from there. Thank you. :cool:
 

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If the thermostat and rad cap and backflush don't cure it and you have verified the fans are running as designed, I would either pull the radiator and have a shop flush it or replace it. A coolant flow restiction will show up quickly when less air is flowing through the radiator as when idling or moving slowly. At speed the added air flow will mask the restriction.

Have you checked for pump flow? Run the engine with the cap removed and watch for continuos flow past the cap opening. Helps to drain some coolant to get the level below the cap opening.
 

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If the thermostat and rad cap and backflush don't cure it and you have verified the fans are running as designed, I would either pull the radiator and have a shop flush it or replace it. A coolant flow restiction will show up quickly when less air is flowing through the radiator as when idling or moving slowly. At speed the added air flow will mask the restriction.

Have you checked for pump flow? Run the engine with the cap removed and watch for continuos flow past the cap opening. Helps to drain some coolant to get the level below the cap opening.
I will look on the radiator side if the thermostat replacement does not fix the engine overheating problem.

I have checked the pump flow by running the engine with the rad cap off:
It did drain some of the extra coolant, but I stopped the process as the overflowing coolant was running along side the radiator... I still have that nice coolant smell now each time the car engine reaches its normal running temperature :angry:. I have since then 'invested' in a pump and have planned to extract the extra fluid that way.

I will keep you posted both on the thermostat replacement and pump flow check... won't happen this weekend though, the wife re-assigned me to a kids bday party... :birthday:
 

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Make sure the system is pressurizing when hot, if not maybe replace the radiator cap?
Worked on mine.
Yes, I will look at the radiator and its cap if the thermostat replacement fails to resolve the issue. Thanks, this is good feedback. :)
 

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Yes, this is the same noise as if I had manually switched from outside to recycle air myself. :ask_wsign
That sounds like a seperate problem... could be a sticking blend door. Did the noise start at the same time as the overheating issues?
 

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Are the fans coming on? If not, see if they come on when the A/C is turned on.
 

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That sounds like a seperate problem... could be a sticking blend door. Did the noise start at the same time as the overheating issues?
The A/C vent noise started after I purged and replaced the coolant, so I suspect it has to do with my changing the cooling fluid.
I am not sure what you mean by sticking blend door...:confused:

The overheating engine problem has always been there... since I bought the vehicle back in 2004 @53k miles (now 140k miles). My purging the coolant and replacing the radiator fan assembly was to get rid of that engine overheating problem, with no success so far.
 

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Are the fans coming on? If not, see if they come on when the A/C is turned on.
Yep, the fans are kicking nicely once the engine is hot enough for them to.

I'm leaning more and more on a thermostat issue... which I have not had the opportunity to do this week end; so it will probably have to wait until next week end before I can do the thermostat replacement.
I will keep you posted.

Thank you for your feedback, very helpful! :)
 

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You could check the pressure by squeezing the upper hose after the engine is normal hot. Should be firm.
Yep, I did that when I was testing that the cooling system was still working after I had replaced the coolant... I will do so again after I change the thermostat.

Thanks!
 

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The A/C vent noise started after I purged and replaced the coolant, so I suspect it has to do with my changing the cooling fluid.
I am not sure what you mean by sticking blend door...:confused:

The overheating engine problem has always been there... since I bought the vehicle back in 2004 @53k miles (now 140k miles). My purging the coolant and replacing the radiator fan assembly was to get rid of that engine overheating problem, with no success so far.
I have to ask you what you mean by overheating? as you say it has been doing this for about 5 years.Does your temp gauge sky rocket to high? I would think that your engine would be fried by now if its been overheating for 5 years.

As far as your fans coming on,this would be normal for stop and go driving in warm weather in traffic,and +90 would have the same effect I would think.

Just wondering how hot your engine is actually getting?
 

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The A/C vent noise started after I purged and replaced the coolant, so I suspect it has to do with my changing the cooling fluid.
I am not sure what you mean by sticking blend door...:confused:.
Actually, I'm not sure! :biggrin:

I didn't mean the blend door. The blend door is a moveable panel inside your ductwork that determines how much cold and hot air gets mixed together to yield the desired air temperature.

What I meant was the recirculation door. There's a motor that moves the door back and forth, either opening or closing the system to the outside air depending on position. Maybe the door or linkage is stuck or something.
 

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Change your THERMOSTAT... that controls the temperature rise and fall in the engine. It is an inexpensive part, and should cure your problem. I am surprized that no one has mentioned this yet! :eek:
That's because I didn't see this thread, till I got back from my daughter's wedding just today. Otherwise, "I" would have recommended it, as well as the rad cap be replaced for "PR".
:lol:


Someone else asked a very good question; How "HOT" does it actually get ? At a stop, mine swings between the 2/3rd to the 1/3 (the high side of the little thermometer emblem, to the low side of the thermometer, back again). This is considered "normal" :thumb:

Above 2/3 is NOT Normal.

Is this the first time you've ever replaced the coolant (140kmiles) ?
 
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