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2006 mustang gt, quickly overheating

8K views 37 replies 10 participants last post by  MasterX 
#1 ·
Roush cold air intake (one month ago installed), recommended level of coolant put in after I noticed it was low, no leaks detected.
new fuel pump, new fuel regulator/sensor, new fuel rail sensor, new MAF sensor. the new items were installed last week and are aftermarket but rated to replace stock parts.

when warming up the car the temp goes higher much faster. normally it stops around 192 but it goes up to 218-225 before the fan kicks in and drops it to 201.
When I drive after it gets to 120 degrees the temperature almost staggers. it will do a quick jump by 10 or 20 but as long as I am cruising the temp will level off.
I only noticed it after hooking up my OBD2 to a garmin mechanic HD to see how everything was running. I have never seen anything like this before.
 
#2 ·
First up, 220 is not really overheating, and also, are you monitoring the coolant temp, or the Cylinder Head Temp PIDs? They are not equal and will show differing values. Coolant will always be lower than Cyl Head Temp because the head is where the fire is, coolant is only passing through.

Coolant temp of 200-225 is normal here in arizona where it gets to 115-120^F outside at times, on a really hot day with the A/C on i have seen 230^F on the coolant, I actually have an alarm set at 230^F, and i kick off the A/C if it goes off, which only happens occasionally, and only when stuck idling in dead traffic at a complete stop. In the winter months, even sitting in traffic, i rarely get over 217^F on Coolant Temp.

Now on the Cylinder Head Temp, I have seen as high as 249^F on hot days, especially if im really laying into it at random times. But there is very little documentation from Ford about what temps are acceptable or dangerous on the Cyl Head Temps, though common sense would indicate that since aluminum looses 1/4 of its strength at 300^F that we want to stay as far away from 300^F as possible. So I usually settle down if i see the cyl head getting up towards 249^F.
 
#3 ·
MasterX;
coolant temp.
even in LA where it was over 90 or 100 I never saw my temp go over 212 and that was being stuck in traffic. When cruising it would be at 192 and that was going up to 70 MPH.
right now where I live it barely gets to 80.
what ever this is, it is not normal
 
#4 ·
Wes,

What does the temp look like with the A/C on which causes the cooling fan to be on too. Does the coolant temp ramp up and stay within the normal range that you are familiar with? Or does it overshoot and then drop down like you notice unusual.

Erik
 
#5 ·
I turned off my AC thinking it would help but nothing seemed to change.

Another update though at least about today, it was still warming up rather quickly however the coolant temp leveled off at 190. I didn't drive any different than before and temperatures today were the same as they have been this past week.
This whole thing is rather confusing
 
#7 ·
I'm pretty sure there are two fan settings, "low" and "high" or something like that; with low kicking in around 180 and high kicking in around 200. I don't remember the exact temperatures but it is something like that. The temps can be adjusted in the tune.

So it sounds like maybe the low fan is not kicking in at all, and the high fan is finally coming on when it hits the high temp. That would explain why it does not get that hot when moving -- because it does not need the fan when moving.

Try some searches on here and hopefully you can find the older thread about this with the details. I think it might be the relay for the low fan.
 
#12 ·
I'm pretty sure there are two fan settings, "low" and "high" or something like that; with low kicking in around 180 and high kicking in around 200. I don't remember the exact temperatures but it is something like that. The temps can be adjusted in the tune.
The low speed fan actually kicks on near 200^F, and high speed at 230^F on the stock tune, for emissions they have these things running hot, i always adjust mine in the tune to run low speed at 180, and high speed around 190, and it keeps things much cooler, but im also in arizona.

As for his temps.
watch the humidity, the higher the humidity the more energy transfer the radiator can accomplish, as the moisture in the air aids in thermal transfer from the surface of the radiator blades to the air. A stretch of super dry and hot days can cause higher temps.
 
#8 ·
JBert, do one of both fans operate when the AC is turned on?

And I didn't read where a tune was installed. Some CAI do not require tunes (not sure if the one bought requires it or not), but it looks like other aftermarket parts he installed were replacememt rated for OEM. But replacing those parts it's not hard to strain the harness onnections on other sensors like the temp sensor. I'm probably grabbing at straws.
 
#10 ·
JBert, do one of both fans operate when the AC is turned on? . . . . And I didn't read where a tune was installed.
I'm pretty sure there is just one physical fan, with two speed settings "low" which comes on first and "high" which comes on at the higher temp setting. I am not sure if the A/C triggers the high or low fan speed, but it does trigger at least one of them.

No Tunes have been installed, the Roush part did not require it. A few of the older posts were similar to mine but my car doesn't seem to be having the same problem exactly.
I will check the sensor and connections though, but I don't know how to check the fan settings, I'll look that up today
I didn't mean to suggest that a tune had caused the issue; rather that you can check the fan temperature settings through the tune/tuner if you have one and you want to know the settings. I doubt your OBD2 scanner can read the settings, but it might; but that is only if you want to find out what they are, since that is probably not the issue since it hasn't been changed.

I think there are separate relays for the two fan speeds, and the relay for the low speed might be the issue -- I remember reading about it in some older posts but don't exactly remember the details.

hope that helps and does not add confusion!
~ John
 
#9 ·
No Tunes have been installed, the Roush part did not require it. A few of the older posts were similar to mine but my car doesn't seem to be having the same problem exactly.
I will check the sensor and connections though, but I don't know how to check the fan settings, I'll look that up today
 
#11 ·
JBert,
no, mine will not be able to see that, it only tells me what the sensors on the car are picking up and codes for the check engine. I will just have to have a mechanic to check it out and the relays. I will keep on eye on here and update what I find out.
 
#13 ·
The first thing to jump out at me is you replaced fuel components. I have seen faulty fuel pumps before. The other components you replaced can be faulty as well. Fuel also helps cool the engine. A lean condition can cause the temps to spike and jump around like your symptoms. Of course this is only a thought as it wasn’t happening before the new parts. Definitely worth a try. They were the only parts changed and temps were fine before.
 
#15 ·
Does anyone know the proper coolant filling procedure for a S197 GT, there seems to be a lot of contention... There are plenty of ways to get it figured out, but there must be an actual set of steps from the MFG to make sure its all 100% proper...
 
#16 ·
1. Fill the cooling system from the expansion reservoir until the level reaches the COLD FULL line.

2. Start the engine and let it idle with the cap off. This will evacuate more air so top up the reservoir as required.

3. Loosen the Allen head bleeder screw on the coolant crossover to evacuate any remaining air (apply a rag around it prior to opening to avoid creating a mess). If there are no bubbles, retighten it.

4. Make sure the expansion reservoir is properly topped up, screw on the cap, and go for a 10+ minute drive. Once finished, park the car with the front pointing uphill if possible.

5. After a minimum 4 hour cool down, recheck the coolant level in the expansion reservoir and top up as required.
 
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#17 ·
I will have the mechanic check to see if it is running lean, ill also recheck the coolant and take those steps to make sure air is evacuated.
did notice something interesting though over the weekend. took my 1st long drive since the parts were replaced and this heat problem started. when I stay above 50 the temp will come down to 194-195. but as soon as I slow down to a stop at a light, the temp will increase again. Didn't see this before with the short drives since I didn't stay above 50 very long.
 
#18 ·
. . . . when I stay above 50 the temp will come down to 194-195. but as soon as I slow down to a stop at a light, the temp will increase again. . . . .
this suggests that either:

a) the low speed fan is not coming on, or not coming on soon enough (when you are moving, especially over 50, there is plenty of air flowing through the radiator without the fan)
or
b) the higher temperature that it rises to is normal, not a problem; but you are noticing it now and think it is a problem (see earlier posts about what is normal operating temperature)
 
#19 ·
Does your fan kick on when you turn on the A/C? Do this test while it's parked. Don't mean to talk down to you but you'd be surprised.
The reason I ask these questions is you said it runs at normal temps on freeway but gets hot when you hit red lights.
The 05-09 GTs are notorious for cooling fan failures.
 
#21 ·
I don't think there's anything wrong with the water pump but the fan may either be switching on too late in low speed mode, or only working in high speed mode. You might want to check the low speed fan relay, and inspect the bottom of the fuse block for any burnt terminals.
Check at what temperature the fan does switch on and report back. Does it switch on when you use the AC?
On the highway, a temp. of 191-194*F (88-90*C) is normal.
 
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#23 ·
The AC and defrost have had no noticeable change. we did get rain the past 2 days and it was still having the same issue. on the 1st of july I will have it in the shop. Mechanic has been given the details so I will find out soon what is causing the issue.
 
#24 ·
The AC and defrost have had no noticeable change. . . . .
meaning the fan does NOT come on, when you turn on the A/C? if so, that confirms a fan problem

I guess it's too late since you already took it to the shop, do let us know what you find out, so we can improve our interweb troubleshooting skills ;-)
 
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#25 ·
I think I have read through the details on this thread but I do not see any mention of the thermostat. He wrote "when warming up the car the temp goes higher much faster. normally it stops around 192 but it goes up to 218" Isn't that about where/when the thermostat should open up, before the fan kicks in? I also do not see much mention about the loss of coolant. He said there was no observable leak but it was low enough that he felt a need bring it up and ask about proper filling. I think that a prolonged time period of running hot might evaporate the coolant and we do not know what sort of mix or even what coolant was in the system, but there could also be an internal leak into the cylinders. I know I am not really helping here but I just wanted to bring up a few possibilities. I would also like to mention that most of us just think of the liquid in the cooling system as something to cool the engine and worry more about it's anti-freezing properties if you live in the north. I know I often forget to consider the anti corrosion aspect of the coolant until it is too late. I do not think it applies to this situation unless something has really corroded very bad, but it is possible the coolant has never been flushed and changed and it would be well over its lifetime.



I hope we get an update as I also enjoy reading about these issues before they happen to my '06.
 
#27 ·
I think I have read through the details on this thread but I do not see any mention of the thermostat. . . . .
Good call on the thermostat as it could indeed be malfunctioning.....
oops yeah I thought he said he already replaced it, way back in post #1, but I must have been confusing this with one of the other recent overheating threads!
 
#26 ·
Good call on the thermostat as it could indeed be malfunctioning.

We're still unsure if there's any actual coolant loss but if there is, a leak from a heater hose in the valley of the engine would be hard to detect. Others would be easier to see unless they're so small that you may only see dried crusts.
 
#28 ·
Mechanics want to check the thermostat but they also want to do a pressure test. The coolant level in the reserve Reservoir was getting low again. The entire time it was in the shop along with when I was looking at it over the weekend there was still no observable leaks. They said the fan was actually kicking on at the correct oil temperatures but today it was a cool temp outside so we are not sure if outside temperature is playing a part.
Also there is no odd smell coming out of the exhaust
 
#29 ·
don't sweat the filling. using the degas reservoir is easiest but takes forever to get the air out. there is a plug on the coolant crossover (drivers side) that takes a allen wrench to loosen, remove that and fill from there, I believe that is the highest point of the cooling system, at least for the 05- mid 07 GT. after that, Ford put the thermostat there. good luck
 
#30 ·
I had a 2006 rx8. The water pump would only leak through the weep hole while driving. Making it very hard to find. Wouldn’t leak while idling either. I was ready to tear the engine down when one day my brother in law was driving behind me and noticed something running out the bottom of the car. So I jacked it up in the driveway and got my wife to put in gear as if she was going down the road. Sure enough coolant was coming out of the week hole on the water pump. Good luck I hope you find it soon.
 
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