Mustang cooling issue

gub

gub

Forum Member
95 Mustang Gt Cooling problem: On warmer days the car will begin to run at a higher temp than normal and continue to rise up to around 215. I know it doesnt sound high, but the car runs different when its high. If i keep the heat on, it will take longer for it to heat up but still does. On cool nights/mornings the temp. will stay low until it sees higher rpms , but the temp will drop back to normal faster. Has an electric fan that comes on somewhat early and will stay on the whole time. Any ideas? The car also has aluminum heads and a THICK aluminum radiator.

thanks
 
If it is taking long to heat up then not cooling down much it sounds like the thermostat has failed and is stuck open.

You need a new thermostat.

--Joe
 
gub said:
A thermosrtat stuck open can make the temp stay hot too?
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Of course, the fluid doesn't stay in the radiator for any amount of time so there is very little heat exchange. It is better than failing closed, but yes the car will still run hot.

The purpose of a thermostat is to bring the car up to temp quickly (to heat the oil), then once at that temp it maintains it.

--Joe
 
Reason why i ask about the heater core is because it will stay cooler for longer when i have the heat on. If the thermostat fails to fix my prob. should i bypass the core?
 
gub said:
Reason why i ask about the heater core is because it will stay cooler for longer when i have the heat on. If the thermostat fails to fix my prob. should i bypass the core?
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Heater core acts as a second radiator if it cools it down some it's working pull the thermostat check it/replace it. I'd keep the heat functioning even if the car dosen't see cold days. My car was driven from mid may till mid September never saw a cold day but I had a thermostat fail on me the same way yours did and by just turning the heat on it kept the car cool enough to get it home to fix it.IMO unless it's a drag car with weight is an issue keep the heater core.
 
chuck-norris said:
Heater core acts as a second radiator if it cools it down some it's working pull the thermostat check it/replace it. I'd keep the heat functioning even if the car dosen't see cold days. My car was driven from mid may till mid September never saw a cold day but I had a thermostat fail on me the same way yours did and by just turning the heat on it kept the car cool enough to get it home to fix it.IMO unless it's a drag car with weight is an issue keep the heater core.
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This.

I almost regret removing mine, but i wanted the space for something else...
 
gub said:
A thermosrtat stuck open can make the temp stay hot too?
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It can be stuck at a point not all the way open.

gub said:
Could it be a bad heater core?
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No, since it cools down, or takes longer to warm up when the heats on, this proves the heater core is exchanging heat efficiently.
gub said:
Reason why i ask about the heater core is because it will stay cooler for longer when i have the heat on. If the thermostat fails to fix my prob. should i bypass the core?
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No, as stated above it's working. Replace the radiator cap, thermostat, and if the problem still exsists, do a water pump. Also make sure the fan is wired properly, and is spinning the right way. Also, look into the rad after you do he stat, make sure you see flow in the rad, and the rad itse;f isn't plugged up.
 
I didnt want to remove the core but i just wanted to see if bypassing it made the problem go away. Though it makes sense that the core is working because it does help out a little. How often do thermostats fail?
 
Does the car sit a lot? What mixture of water you using? Any previous coolant contaminants entered the cooling system? Has the car over heated due to fan problems? Is the car driven in all climates?

Theres no cut and dry answer to your question.
 
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Car is daily driven. Im using 50/50 coolant. not sure about contaminants. And i dont thing it has overheated to fan problems, the fan stays on for a while. I have owned the car since june so not sure about climates.

Also what size thermostat should i use? I took out the thermostat on the car and it was a 160.
 
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Put a stock one in there and see what happens. Use a good brand to limit the probability of defective part.
 
Not sure what stock is for these cars, but i pulled a 160 out of it, im going to put in a 180
 
I think 190 or a 195 would be stock... a 190 with a 1/8th hole drilled thru it would be something I'd try first.
 
The car doesnt runs bad when its over 200. Could timing have anything to do with it?
 
gub said:
The car doesnt runs bad when its over 200. Could timing have anything to do with it?
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Possibly. CHeck the timing, if it seems oddly off, make sure the balancer hasn't spun. The rubber often gets old and dry rotted and the outer and inner ring can get offset. PUt the 180 in it with an 1/8 hole drilled in the plate. Should get you where you need to be. 190-195 is the factory stat, but most guys succesfully go to a 180 and works just fine.
 
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