2005 GT Overheating

nbk13nw

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A long story here…

About a week ago while driving to the local store, the dash alerted me to an engine overheat condition. It only lasted a second or two and then the gauge dropped and returned to normal. I decided to use Torque Pro while driving to monitor the temperature.

I found it hitting 230f and hovering around that temp. It varied between 220f and 230f. It was a short drive of less than 5 miles and 45mph to 60mph. So I finished the run and returned home. Once home I decided to look further.

Checked the coolant level and all was good. No leaks and the tank had pressure. But a strong smell of coolant heated up.
That day I bought a new thermostat, drained and installed it and filled it back up. It had the same issue as before with the temperature eventually reaching 235f.

I had flushed the system back in May and had no issues until that day. So I started checking the fan. I set the fan low on to 189c and the high on at 194c. The fan kicked s expected when the temperatures were reached so fan is not the issue. I figure with 172K miles that maybe the pump was going bad. So I bought a new one and installed it, as well as more coolant (50 / 50 mix distilled water and coolant).

The car was still overheating after all this so I dropped the car off at the dealer. Several hours later, and $195 for a flush and troubleshooting, I picked up my car. They told me they could find nothing wrong. On the 5 mile drive home, yup, it overheated yet again.

So I figured now one last thing. Bought a Mishimoto Aluminum radiator (Looks nice and built well by the way) and installed it this evening. And yes it is still overheating after all this. Mind you, if I run the heater it blows hot air and brings the temperature down.

However, this time I started looking at the hoses since it did take the heater longer than usual to start blowing hot. The lower hose (Outlet) is not pressurized and it cool to the touch (Ambient temperature) while the upper radiator hose (Inlet) is very hot and pressurized. This leads me to think it is thermostat related. It is not opening.

So after spending way too money (Water pump, thermostat, radiator and I lost count of gallons of coolant), am I wrong in suspecting that the new thermostat is bad, not opening?
 
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LordBritish

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I had a similar problem. Turned out to be a stuck thermostat. It was replaced under warranty at the time so it cost me $0.
 

sman247

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try a 60/40 mix water/coolant, but that def sounds like a stuck themostat. Very easy to change yourself and a very inexpensive part.
 

nbk13nw

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Yes I changed out to a new one a few days ago but I never tested it before I installed it. So I am hitting the dealer tomorrow to pick up another one.

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Born To Run

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Over heating

Thermostat in upside down backwards?.
Turn it over & try it.
Always boil water on stove & verify thermostat opens before installing.
 

Dino Dino Bambino

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So after spending way too money (Water pump, thermostat, radiator and I lost count of gallons of coolant), am I wrong in suspecting that the new thermostat is bad, not opening?

It could be but one possibility you haven't considered is that there could be air trapped in the cooling system.
The '05-'06 GT models have a bolt in the center of this picture that you can unscrew to bleed the system. Do it from a cold start with the engine at idle speed.

86824d1262226636-cooling-system-bleeding-001.jpg
 

86GT351

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Very good idea to bleed the system. Air pocket will surely cause your concern. Try that first before chasing another thermostat
 

Pentalab

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Very good idea to bleed the system. Air pocket will surely cause your concern. Try that first before chasing another thermostat

That's why they vac fill the coolant. Normal deal is the low speed fan is set to 204 F....and high speed fan set to 215 F.
The T stat on my 2010 is 190 F.
 

86GT351

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Correct. However not everyone owns a vac fill coolant tool. For those that have it they work amazing. Hence the reason to open the bleeder hex and verify there is no air pocket.
 

redfirepearlgt

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I would go back and check belt mapping. You may have fixed your problem and induced another when you replaced the water pump if you routed the belt wrong on. It is possible to do and will cause the pump to rotate CW vice CCW. According to the Ford Shop manual the pump rotates counterclockwise (anticlockwise for some folks) when looking at it from the front of the car. If it is running backwards it still can produce SOME water movement but not enough. You wouldn't be the first to have done this. Just verify it. It's a simple check.
 

nbk13nw

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All good recommendations for belt mapping and bleeding. I will give it another shot today and see if I can figure it out. I did pick up another thermostat and tested it this morning. Before I drain it again I will double check everything

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nbk13nw

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So I checked the belt mapping and it is correct. I pulled the thermostat again and it was correct but I replaced it with the tested / working thermostat. Now to bleed the system. Looks like a squared fitting is needed to remove the bleed valve. Let me see what I can find
 

Dino Dino Bambino

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I would go back and check belt mapping. You may have fixed your problem and induced another when you replaced the water pump if you routed the belt wrong on. It is possible to do and will cause the pump to rotate CW vice CCW.

If you remember these general rules you can't go wrong:

1. Ribbed pulleys spin clockwise, and smooth-surfaced pulleys spin CCW.
2. The ribbed surface of the drivebelt mates with ribbed pulleys, and the smooth surface of the belt mates with smooth-surfaced pulleys.
 

nbk13nw

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So far so good. Ran it for 30 minutes at idle and never got above 206f. Going to take it for a test drive during lunch hour and see how the temperature holds in traffic and on interstate. BTW... I did burp it using the bleed fitting this time. I would think that the dealer would have done the same. So I figure the thermostat I bought the other day was stuck in the closed position.

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nbk13nw

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Update:

Highway it settles in at 201f, in the city it settles in at 199f. Seems to working just fine with the new thermostat. Thank you again for all of your assistance double checking my work.
 
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truckman7

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It could still be the thermostat. Test it by putting it in hot water and see if it opens up. If it does it's not the problem. But also look at the housing as well. Might have a clog somewhere. If it's kicking in the fans at the correct temp I don't think it's your temp sensor. I also thought that the 05 comes with the red anti freeze.


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