Overheating

[parchisi]

Hey guys, well, I posted this same question a little while back but things aren't any better.

I have a '93 cobra that I just bought. Its been overheating. It has an electric fan that I've hotwired to a switch so I can turn it on and off at will. I just replaced the thermostat, still overheated. Replaced the water pump, still overheats, and I just replaced the radiator, still overheating. I've made sure that all the air pockets are out of the system and coolant is 50/50 mix. I'm at wits end here and have no idea wtf is going on. If ya'all got any ideas, I'm anxious to hear them. Thanks!

 

[Mustang5L5]

Little more detail needed


Does it overheat while driving?? On the highway or stop and go traffic? How do you verify that it is overheating? Are you checking the stock gauge? Which coolant are you using? The green colored coolant?

Have you done a compression test to see if you have popped a head gasket?

 

[1992mustangLX]

you are judging the overheating issue on the guage or is the coolant boiling? Im sure you have already thought of this scenario but just throwing it out there

 

[parchisi]

Its an autometer gauge, and just to check, i've let it go all the way over boiling over.

As far as specifics on when it overheats, it seems to be ok when sitting, idling, and the temp really jumps when I start driving, when the engine is under load. Yes, I am using the green stuff. Prestone.

No, I have not checked to see if I've blown a headgasket, but I'm not losing any coolant, the coolant doesn't smell like fuel, nor is there any white smoke coming out of the tailpipe as with my '95 that just blew a headgasket. But I guess a compression test would be conclusive.

 

[Mustang5L5]

Do you have the black air deflector mounted underneath the radiator??

 

[HISSIN50]

Have you replaced the cap? It's often overlooked and the difference between it being fully functional and not is approx 45*F in increased boiling point temperature.

I would put a cooling system pressure tester on there and see how it does.

Good luck.

 

[88mouse]

Whats your timeing set at?

 

[Shakerhood]

What Electric Fan do you have, it may not be able to pull enough air.

 

[parchisi]

I do not think that it is the e-fan only because it overheats while at speed also, like 60 mph. I'll try the radiator cap, check the timing, and do a coolant pressure test. THanks for all the suggestions guys. I really appreciate it.

 

[Mustang5L5]

Do you have the black air deflector mounted underneath the radiator??

 

[parchisi]

Do you have the black air deflector mounted underneath the radiator??

Yeah, sorry, forgot to mention that.

 

[parchisi]

Well, I think I might have fixed it. Checked the timing, and for reasons unknown to me, it was set at 0 degrees. I advanced it to 10, and now the needle is staying at the 230 mark. That's still hot, but the important thing is that its STAYING there. It could be just that the gauge is just off but it is no longer pegged. Also, with an extra 10 degrees of timing, she's much quicker. Thanks everybody for all the help

 

[Mustang5L5]

230 is still hot. This is a near stock motor correct?? By that i mean no crazy mods like a big cam, heads or supercharger??

If so, you should be down around the 190-200range. My own 5.0 stays religiously at 188* no matter what.

230 is right on the borderline of overheating and warping aluminum cylinder heads

 

[parchisi]

well, there's some more weird stuff going on. I still think its running hot, like you said, but there's more. I drove it again with the fan on, and it started overheating again. I turned it off, then the temperature stopped rising, and went down a bit. This doesn't really make sense, but tomorrow I'm going to take the fan completely off, then drive it to see if the electric fan unit is somehow messing up airflow through the radiator or something.

 

[parchisi]

double post

 

[HISSIN50]

Is the fan blowing towards the front of the car (pushing, rather than pulling)?

 

[Jkstang78]

No one ever asked what temp degree of thermostat he was running.

 

[parchisi]

The fan is blowing towards the engine (pulling), I've checked that. Thermostat is either 185 or 195....I don't remember which. That's another thing I might try, just taking the thermostat out and seeing what happens.

 

[Mustang5L5]

Did you check the cap??

 

[parchisi]

Yeah, new cap. I took out the fan unit completely, and it kinda went between 210 and 230 the whole time I was driving. I really don't have a clue of whats going on, but what I will do is replace that e-fan unit with a clutch driven fan like I think came stock. I'm starting to wonder if there isn't some blocked coolant passage somewhere in the engine.......