Overheating at idle

mitchgaglione

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So my 03 cobra will overheat at idle bit is fine when I’m driving. Temps at idle will hit about 245 degrees and while driving on the highway will be at about 208-214. Yesterday I had taken it to a ford dealer and had them do a coolant flush. Before I took it there it wouldn’t overheat at idle. Today I was at the Dunkin’ Donuts drive through and there was a bit of a line so the temps when up to 246. I stopped at a gas station right across the street after and when I shut the car off I saw coolant on the ground. I opened the hood and saw that it had come out of the reserve tank cap. Did Ford mess something up? Not sure what the problem is. Water pump and thermostat are brand new. Crossover pipe O-rings are brand new. It’s not leaking from anywhere other than the reserve tank cap when it’s hot. Any suggestions?


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01yellercobra

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First thing to to check for leaks. You should be able to rent a tester at a local parts store. Also pressure test the radiator cap. They do wear out. And if it won't hold pressure it'll spill coolant out even when things are working normally.

If all that checks out then fill and burp the system. And then check your fan for coming on. I'm guessing since it hit 245 the fan is done. A quick check is to turn the A/C on. The fan should turn on with the A/C.
 

Mojo88

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If engine gets too hot, the cap will relieve some of the pressure (and coolant may come out), otherwise you'd blow up a hose or something.

I would first check for the obvious..... is there something blocking the radiator? I've had this happen with a couple of different cars, a plastic bag gets caught on the radiator and engine overheats.

And I totally concur with others about the fan(s). That baby should be spinning on 'Hi' if that engine is at 246*, or come on with the A/C.
 
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DSG2003Mach1

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Once filled and burped correctly (the procedure is easily found if you’re not up to speed)

make sure the fan is plugged in and working as suggested

my guess is fan is not working or dealership didn’t actually use a flush machine and didn’t burp properly
 

mitchgaglione

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Another update:

Went to auto zone refilled the coolant, bought a new radiator cap, and lowered the temp that the fan speeds come on at. Let it idle for about 10 minutes and temp stayed at about 210. Proceeded to do a few pulls and temps didn’t go over 210. Fans are working as well. Was it just a bad radiator cap?


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hotcobra03

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Oem tank issues over the years.

Cap has worked for some
Slight file across top for some
Crack on bottom of tank is another
 

Mojo88

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Another update:

Went to auto zone refilled the coolant, bought a new radiator cap, and lowered the temp that the fan speeds come on at. Let it idle for about 10 minutes and temp stayed at about 210. Proceeded to do a few pulls and temps didn’t go over 210. Fans are working as well. Was it just a bad radiator cap?


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Nice work! I think it 'might' have been the cap... perhaps if the old cap had bad spring and was releasing coolant at very low pressures, then you may have been running low on coolant?

My other thought is that it may have burped itself.

Either way, stay cool bro....... ;)
 

mitchgaglione

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So I’m pretty sure ford messed up with the coolant flush because I’ve been going for small drives, letting it cool, and filling the tank back up. Once it cools down to a certain point I can see the coolant level drop in the tank from the fill line to the bottom of the tank. So there must still be air in the system. I have no idea how Ford could have messed up that badly. It was Metro Ford of OKlahoma City that I went to. I am on a road trip right now from Twentynine Palms, CA to Jacksonville, NC and I already left OKC and I’m in Memphis now so I’m going to have to take it to a dealer here and see if they can do something about this because the flush at the dealer is not cheap. They charged me about $220 so I hope they can fill my coolant up properly without charging me. Also my crossover plug is stripped and I can’t get it off. Any suggestions on how to remove it?
 

DSG2003Mach1

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It’s damned near impossible to fill correctly through the res. If the crossover plug is stripped you MIGHT be able to use vice grips around it otherwise might have to weld something to it then replace it
 

wckdvnm

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So I’m pretty sure ford messed up with the coolant flush because I’ve been going for small drives, letting it cool, and filling the tank back up. Once it cools down to a certain point I can see the coolant level drop in the tank from the fill line to the bottom of the tank. So there must still be air in the system. I have no idea how Ford could have messed up that badly. It was Metro Ford of OKlahoma City that I went to. I am on a road trip right now from Twentynine Palms, CA to Jacksonville, NC and I already left OKC and I’m in Memphis now so I’m going to have to take it to a dealer here and see if they can do something about this because the flush at the dealer is not cheap. They charged me about $220 so I hope they can fill my coolant up properly without charging me. Also my crossover plug is stripped and I can’t get it off. Any suggestions on how to remove it?

Vice grips work but be careful you can damage the crossover as the metal is soft around the opening.
 

hotcobra03

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Here is how I fill.

I fill tank till full
Leave cap off

Go to cross over and continue to fill until it over flows out tank.

Put on cap. Fill at plug till it’s full

Put on plug

Run car till low speed kicks on

Shut off.

Let cool a couple mins while you slowly remove cap. Air will blow out.

Once cap is off. Repeat steps

Twice should be enough.
Later. A nut can be welded to plug

Plug is an oring seal don’t crank down when you put it on
Just a bump is enough
 

Fastback

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So I’m pretty sure ford messed up with the coolant flush because I’ve been going for small drives, letting it cool, and filling the tank back up. Once it cools down to a certain point I can see the coolant level drop in the tank from the fill line to the bottom of the tank. So there must still be air in the system. I have no idea how Ford could have messed up that badly. It was Metro Ford of OKlahoma City that I went to. I am on a road trip right now from Twentynine Palms, CA to Jacksonville, NC and I already left OKC and I’m in Memphis now so I’m going to have to take it to a dealer here and see if they can do something about this because the flush at the dealer is not cheap. They charged me about $220 so I hope they can fill my coolant up properly without charging me. Also my crossover plug is stripped and I can’t get it off. Any suggestions on how to remove it?

Sounds like you were having problems before taking it to ford. As per the posts from May. You were hoping ford coolant flush would be the saving Grace. I cannot remember if it was you or someone else I told. Get the airlift pump. It makes it fool proof, if your cooling system is working properly. Also no need to fill at crossover if using this system. But with coolant running out that quick, would make me very weary.

 
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BUNKY

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Take it back to who ever did the work and have the master mechanic work on it.
Check all the old work.
When they flushed the system they could have loosened up stuff that's is now caught in the system?


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