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I have a 1977 Mustang II and it's been overheating a lot the past week or so. I'll get into it to drive to school in the morning and on the way the temperature gauge will go from cool to hot, then back to cool, then back to hot, then it'll idle in the middle for a little then go back up to overheating. It's really random. Sometimes it overheats when I'm at a stop light and sometimes it'll overheat when I'm driving 50 mph down the road. There's not really a pattern or anything to it. The fan is blowing fine (or at least it is when I'm look at it) and I just put more coolant in. So, I don't know what the deal is. What are some possible reasons that it could be doing this. Thanks a lot!
 

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This almost sounds like a low coolant level problem, the coolant is flashing to steam and recondensing. You may also notice a gurgling sound a as air bubble pass through the heater core. When cold, top off the radiator with a 50/50 mix and replace the radiator cap. If this doesn't fix the problem, you might be looking at a bad thermostat or even a bad water pump
 

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Sounds to me like you have a "sticky" thermostat!

On your car this is not a real hard thing to take care of! Don' tknow how much you know about engines, but this is a good place to start!

Follow top radiator hose down to engine, - where it hooks on is the thermostat housing, - it is held on by two nuts (or bolts), - possibly may have a bracket or two that need to be removed to get off. Once you have the securing bolts or nuts off, you can lift this piece off, - (it may be stuck and require a couple heavy taps with handle of screwdriver to knock loose)! Lift up carefully and look at the top of thermostat (so you know which side goes up)! - it should have a "pointy thing" sticking up with a small screw visable, (this is the top), -- and part inside housing towards engine has a spring looking thing with a small "wart" below the thermostat plate! This is the "pellet" which senses tempreature and tells thermostat to open!

Clean mating surfaces well, put new thermostat in with proper side up (as you saw one taken out --- if it was properly installed- don't count on it)- this is why I explained which side was up!! Make sure the wide flange of thermostat is within the small depression in housing it fits in, -- if it is off and sticks up on one side, it will break housing when you bolt it down! . Now lay new gasket provided with thermostat (make sure it is in box), - some mfrs. sell thermostat without, and you have to buy gasket extra. If mating surfaces are faily smooth yet, you probably don't need to worry about sealer, and ,most gaskets do not need sealer if surfaces good, - but if badly pitted and goghed out, you probably need ot use some sort of sealer for safe sealing, -- silicone based sealers work fine for this!

Of course before you start a large pan underneath front of engine to catch anti-freeeze as it runs out would be helpful, -- only a quart or less is likely to run out, but even that much is a mess to clean up (and of course you can strain the water and use it again) Water loss probaly not a big deal, and you can top up with water without changing total mix to a great extent!

Since this is not a "modern electronic marvel" and does not have the max in pollution junk all over engine, it is farirly easy and stratight foreward to work on!
 

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i have a 78,and there's nothing like a new radiator and thermostat to ease your nerves.1-800-radiator.they deliver it to your door.the stat you'll have to get from your parts store.depending on where you like get the closest recomended temp theremostat.or change it 2wice a year with the weather.don't run it without a thermost.your engine will run to cool out side while the inside is hoter.thus wearing parts at a greater rate.
 

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first when cold remove radiator cap and fill crank and watch add more if needed fill over flow jug.. if you watch coolant in radiator you can see if the coolant is moving a lot or not or if the thermostat is working by the way the coolant moves up and down every few minutes.. car over heat s short trip most likely thermostat
 

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I had a very similar problem with my car. My mechanic thought I had a leak in my radiator, and tried putting some stuff in it to plug up the leak. It didn't work though, and eventually my head gasket went ( = dead car most of the time. Head gaskets are expensive to fix). Take it to a specialist, not just your local mechanic. Good luck!
 
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