Hi all,

New member and 1st time Mustang owner. I bought a 2008 GT in Jan. of this year and have had strange issues with it since. Right after buying it I had a coolant flush done, since it's something I always do with a used car I buy. Since then I've had to replace the thermostat (no big deal) since it was stuck open. Now I'm getting overheating issues (twice within 3 weeks) with coolant loss (1 gallon both times) and no leaks whatsoever. The car has been on a rack 2X at a local shop and now 2 X at a local Ford dealership service center and no leaks anywhere. Both shops did a compression test on the block and a pressure test on the coolant system and both passed. Both places thought head gasket but apparently not. Only other thing I can think of is the water pump, but I'm not seeing any fluid loss from the weep hole or on the ground anywhere- nor smell it burning off. Only mods I have on it is a Pypes off-road h-pipe and a 93 octane race tune from Bama tunes. I dropped the stock tune back on it prior to the last overheat issue. Anyone have any ideas or need more information???? Any help is appreciated.

 

If the car overheated bad enough some of the coolant loss could be due to overflow through the expansion tank. If your electric fan isn't coming on that would cause the car to overheat.

 

Thanks for the reply 05YellowGT. I have verified the fan comes on and is working right. At least it seems to be. I picked it up from Ford yesterday and will keep a close eye on the coolant. Just very strange there are no leaks and compression is good. Not sure which direction to go from here and neither is Ford.

 

Is the thermostat opening?

 

It is. It was replaced in Feb. to be safe after the flush. I've taken it off and put it in boiling water to verify as well. It's got to have a leak somewhere but not sure how several folks are missing it, especially with the amount of coolant missing each time.

 

Are you confident that the thermostat is working properly? Have you changed the radiator cap? Maybe it's a combination of bad t-stat (you got aftermarket?) and a worn out radiator cap seal blowing out coolant.


Other guess would be heater hoses. Have you changed them? You might not notice a leak by the firewall.

 

Did you burp the system might have air bubbles.

 

Yes. It was done a few times at both places. I had to put more coolant in it yesterday (1/2 gallon in a week) so it's losing it much quicker now. Looks like I'll know soon what the problem is... Thanks for the reply!

 

Had a problem on my 01gt the plastic intake cracked if I'm not mistaken the 05 to 09 had plastic intake could be cracked

 

Hmmm. The intake is plastic. The Ford dealership said they pulled it off to visually check the heads from the outside. They may have cracked it or it may have been cracked already and they didn't notice. I'll take a look and see. Thanks!!