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Weird overheating issues

7K views 29 replies 9 participants last post by  crjackson 
#1 ·
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.
 
#2 ·
Thats very strange. How could you lose 2 gallons of coolant with no leaks? Your coolant level on the reservoir should go down after the first time you start the car after draining the coolant when it starts to cycle, but it should be it.

The water pumps on these cars usually last a long time to my knowledge. Check all of your hoses and make sure your fan is running correctly. Also, since you have a Bama tune, you can lower your fan temperatures. I live in Florida and it gets insanely hot here, hot enough to where my engine was running very sluggish and my clutch would even slip a little. I lowered my fan temps to 192 low and 202 high so it could come on eariler and it helped. I've since put in a Mishimoto radiator and GT500 fan and it helped a whole lot.

How did you know that your thermostat was stuck open? Did your engine throw a code? I'm curious because I never changed mine. If your thermostat was stuck open when it would make the coolant flow too fast through the radiator before it had a chance to cool off and your engine would probably overheat. I hope your new one is working better.

There is one more place you can check for leaks, and thats behind the alternator. Theres some coolant lines running behind there. Those are static lines so I don't see why it would be leaking from there but who knows.



I'm kinda a noob to be honest but thats my take on things. Maybe someone who knows more will chime in.
 
#3 ·
Thanks for the reply SangheiliSpecOp. That's exactly what I said about no leaks. It's a closed system so it has to be coming out somewhere. Actually after looking at pics of thermostats it was stuck closed. I assumed since it was expanded it was open. I'll check the tuner for lowering the temp as it gets pretty hot here in the summer as well (North Alabama). I'll also check behind the alternator since I had it replaced a few months ago and I could have damaged those without noticing. I picked it up from Ford yesterday and marked the tank where the coolant level was and will keep and eye on it. Appreciate the help!
 
#5 · (Edited)
Thanks Strange Mud. Yes that's a real number from Firestone the past 2 times I've taken it in there when overheating. Exactly 3 weeks apart and exactly 1 gallon of coolant gone both times. Car runs really well so I don't notice any performance issues at all. I thought for sure Ford would catch whatever is going on but not yet.
 
#6 ·
Any steam when it overheats? I changed my thermostat and the radiator cap and still overheated. Not sure how this works but the technician that worked on the car last, (05 GT) also did a full system pressure check after the cap and thermostat and no leaks. Anyway, what e thinks was the problem was an air bubble in the cooling system, even though "they" did all the steps to make sure the car didn't have any air in the system. Good luck, mines seem to be OK noe, (knock on wood!).
 
#7 ·
Thanks for the reply Gil05GT,

No obvious signs of overheating at all. No steam, no smell of coolant, etc... only sign is the small hose going from the overflow tank back to the radiator is boiling. Pressure test was done at a local shop and a Ford shop with no signs of leaks. I had to put 1/2 gallon in it yesterday before going to work. It's warrantied so if it goes , it goes...:banghead:
 
#8 ·
I wonder if it's the intake manifold. On my 04 the manifold was leaking and the water was running into the valley of the block and boiling off. I wonder if this is going to be an issue on the s197's as well as they are starting to age.


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#9 ·
Thanks for the reply,

I had the cylinder head temp sensor replaced, which required taking the manifold off but didn't see anything leaking in the valley. It's weird because I don't smell any coolant burning off when it overheats. It's overheating because it's losing coolant (I'm adding 1/2 gallon a week). Just surprised no one could figure out where it's going... I thought Ford would figure it out for sure. If it were burning off on top of one of the pistons it would be in the oil correct? Even if it wasn't getting past the piston rings it seems like it would still show up in the oil (or not?).
 
#11 · (Edited)
Thanks for the reply again Strange Mud,

No, it was one of the many things I tried in order to figure out if that was the problem or not. First was the thermostat, which was bad, then the temp sensor, a good check of the water pump, which looked good... The temp gauge itself didn't work until I had the coolant system flushed right after buying it. Then the gauge worked off and on but eventually started working all the time. I thought the gauge was bad for a while but looks like it's not. It's definitely overheating due to coolant loss just can't pin point where. I'm still hung up on head gasket or water pump due to the coolant flush, but no leaks anywhere. I'm as stumped as everyone else...

EDIT: Barrs may be a good way to go just to see if I still lose coolant or not. It's runs like a champ so I can't believe it's anything very srs wrong. The idle stumble I had for a bit turned out to be the tune. It's fixed now or at least looks like it.
 
#14 ·
I've never used it before so kind of nervous. I have made some sort of progress though. I've attached pics to see. Looks like the intake manifold is leaking. It wasn't before but now that the coolant loss has worsened I just noticed it. Ford pulled it off the last time they had it and may have not torqued it down right... Notice the white film over the coil pack that covers the plugs. Still doesn't explain where it was going before though.

Edit: I'm going to clean it up real good and keep an eye on it.

 
#15 ·
Just thought I'd resurect this thread with an update. It was the head gasket on the driver's side that failed. Pulled top end apart and the system is sludged up really bad and can see metal flakes underneath the cams on both sides. I have another issue though... I found a replacement motor but my 08 has a production date of 11/07 while the replacement motor has a production date of 12/03. I understand there were some major changes with the newer production date motors. Coolant routed differently? Different heads due to the old plugs being 2 piece and breaking off? Can anyone confirm this? Also would the newer production date motor work with my car? Haven't been able to get a straight answer from anyone here.

Thanks all!
 
#17 ·
Thanks Jbone. I found a few longblock replacements; one with 6k miles on it and another with 21k miles on it at a local place. I have the accessories from my old engine (alternator, starter, etc...) I contacted several places to be sure and all but one said it couldn't be done. The one place that said it could be done told me I'd need my intake from the old motor, new plugs (since mine is 12mm and new one is 16mm, and new COPs (along with my accessories) and it wouldn't be a problem. The shop that has the motor swears it won't work though. Just trying to verify for sure. Thanks again!
 
#18 ·
Would have to dig a bit more and see all of the differences but would think that it should work with what you stated above. Check with ford and see if there is a part # difference between the intake for the different engines production dates if not then you should be good to go with yours. Is the replacement Engine from a Mustang or something else (like a F-150)?
 
#19 ·
I called the local Ford dealer's parts/service department but was told they didn't have any information on it lol... I got the feeling if I were buying the motor from them they would've told me.

The shop that said it could be done was using the Hollander computer system that alot of salvage yards use to check interchangeability of parts/motors and said the only differences in that system notes he saw was the bigger plugs needed, new cop's, and the need for my intake on the new motor. The motors the local shop has available are both out of Mustangs. The 6k mile motor is out of an 08 and the 21k mile one is out of a 2010. Just the production date difference... Thanks!
 
#23 ·
Sure! They want $1,850 for either (not sure why they're the same price with different mileage). A buddy of mine has been there several times and has been able to talk them down $100-$200 everytime, so I'll haggle with them. Budget is set at $3,500. I'd love to throw a 5.0 in it but money (and know how) doesn't permit it this time. I am going to throw some performance parts on it before I put it in though- Comp cams, shorty headers, CAI, and a few others if the money is there. Thanks!
 
#24 ·
Yep you would spend quite a bit more than that on the 5.0 swap but would not hurt to look around may find a good low mileage one for a good price. Check around and see what that other folks are using. Good Tune is what most will recommend 1st, CAI are more appearance than performance as the Stock has very good airflow. But I have a K&N on mine and I love it just for the appearance factor. Same with the shorty headers, look for a tuned set, or go long tube if you can get away with it:thumb:. Not sure on your Smog rules there.
 

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#25 ·
Quite a bit more I'm sure. I'll keep my eyes open though. I have a Bama tuner with the performance and race tune on it so I can tune it as needed. Looking forward to getting started on this project as I'm anxious to get done already. Yours is beautiful! I love the new 5.0 body style and power. I'll have to save up for that though!
 
#27 ·
I've never driven a 5.0 but the GT is so much fun to get the as* end around on it. Enough HP for me (for right now). I can't imagine 100+ HP more with a 5.0.

Just another update. I was able to finally pull the engine out this past Saturday. If no one has ever done it I can say it was much easier than I thought. I'm not a mechanic but know the ins and outs of cars. This was the first motor I've pulled ever. Heads were sludged up pretty good and the oil pan had metal flake and sludge in it as well.

The back cylinder already had that coolant in it. Just waiting for the new motor and she'll be ready to go back together. If anyone has any questions about how I pulled the motor out just PM me.

Alright gents,

It's been a while but I ordered shorty headers, clutch, motor mounts, throw out bearing, and a few other goodies from AM a few nights ago. I'm picking up the motor tomorrow and hoping to have it in and running this weekend (but looks like parts may be shipping slow). The motor has 6k miles on it and is from an automatic so I'll have to pull off a few things to install the clutch. Flywheel is going to a local shop tomorrow for re-surfacing. I'm going to get it running first then do the cam swap after everything is stable. Any tips as far as break in? the way I understand it that's done at the manufacturers nowadays?

So the motor has been in for a week now after having some minor issues. Ended up with the motor out of a 2010 GT with 22k miles on it. The bell housing spacer is rubbing the back of the flywheel. Took it to a shop to have it fixed.. .Transmission was dropped and was supposed to be fixed but it's still doing it. The biggest concern I have right now is no low end torque or power. When leaving in 1st gear it just sputters and misses... No power at all. Top end is fine. Once it's in 3rd gear and higher rpm's she wants to just go like hell. Really strange. It was throwing a code (P0155) for an O2 sensor which I replaced and after clearing that code with my SCT X4 tuner popped back up yesterday. Also had a P0304 code yesterday (Misfire cylinder 4) I'm going to pull the plug for cylinder 4 and check it along with swapping the coil pack with a spare one I have. Can anyone explain the loss of low end power? It was running this way from day one- sputtering/missing/backfires... Is it the computer and wiring harness? I had to use the wiring harness for my old motor since a connector for the fuse box on the 2010 wiring harness was different. Any help is very much appreciated.
 
#28 ·
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.
I have A 2010 ford mustang GT the problem you for the leak, is the intake manifold pipe. I had the same problem. But i have fix it.
The problem is when coolant leak on the hor engine block, it steam and dry quikly.
The next overheat problem you haven't its the Bama tune. if you can return your vehicle to stock. Since Bama rev your engine from 700 RPM to 900 RPM .
Causing an overheat
 
#30 ·
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