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I have a 79 f150. It was dumping coolant out of the overflow when i shut it off so I put aftermarket gauges in there and new coolant. It was fine until today on my way home from work sitting in traffic my temp jumped up to 230. I removed the thermostat whhich seemed good and drove it and it's still overheating. The previous owner put water in it instead of anti-freeze so the radiotor has that rusty color to it inside. What could be causing this and how can i fix it. P.s. when I rev it up when its hot the gauge goes back down to about 190 which I think is normal.
 

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Overheating while sitting usualy indicates an air flow problem.
Assuming that your fan shroud is good, my first suspect would be the clutch fan.

DGW
 

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if you pulled the thermostat and it stil does it its not that, so is your fan clutch working? is your water pump circulating the coolant? head gasket could be blown and pressurizing the system too... there was a post here recently Il try and find that had a good way fro checking vacuum and compression... ill try and find that... when it gets hot an fills the overflow tank, it will be sucked back in to system when it cools, so if you lost coolant it pulled air back into the system when it cooled... you should definitely drain, flush, and refill because of the nasty water regardless...
 

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I would look to the rust as being an issue. A complete system flush and possible replacement of the radiator and possibly the water pump as well. The radiator may be done due to rust, and if that crap has been in the system for a long period of time, it could be causing havoc in other parts of the cooling system....
 

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you dont have whats in this picture? should be clutch bolted to pulley and fan blade bolted to the clutch...



 

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If you still have the thermostat removed then take off the cap (when the motor is cold) and warm up the truck on idle. The coolant should be moving a little. If it is still then you probably have a water pump problem. If you get bubbles showing up when you rev the motor then you could have a blown head gasket. 230deg isn't good, but it isn't really that bad either.
If you have movement and no bubbles make sure that nothing has blocked off the radiator fins - I once had a buddy get a piece of paper stuck between the AC condenser and the radiator that caused overheating problems.
With all that done I'd go pick up a 160deg thermostat. Running a thermostat is always better than going without - and they are cheap!
 

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i had the same issue, my water pump was bad. besides a blown head gasket gives you other signs like thick smoke out the tail pipe. on one car with a crack in it i even found the oil and coolant mixing. believe me, if it was a head gasket you would see more symtoms. i would investigate your water pump. oh! and i say go with 180-degree thermostat. i know that a 160 degree is made for my car, but it messes with my computer and rated for racing only. it makes the car think it is having a cold start or something. i know these old fords don't have modern computers, but they are made to run a certain temperture. 180 helps your system cool at 180 degrees instead of 195 degrees. this is a safe change. i have also seen that people running 160 degree thermostats build up excess carbon because the engine didn't get hot enough to burn it. engineers were paid lots of money to design your engine to last you along time, i'm sure they designed the motor to run a certain temperture for a reason. don't stray too far from pecs unless this truck is your toy and not a daily driver. My grandfather has always told me one thing about driving a four wheel drive, "Experience is expenssive."
 

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water pump trouble shooting.

When my water pump went out, my grand father taught me to remove one of the hoses on the raideator. if your pump is working, it should push out your water quickly. if not, or if it is slow then you have solved your problem.

good luck to you
 

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Coolant temperature is used for a variety of engine and emission control functions. The coolant sensor on late model engines tells the computer when the engine has reached normal operating temperature. This, in turn, affects fuel enrichment, spark timing, operation of the EGR valve, purging of the charcoal canister, etc. It wont hurt you on your older vehicle provided you arent required to do a smog test where you are as this might cause you to fail... also your weater wont work as well in the winter I might add... when the vehicle is cold, pop the cap, start her up and watch for flow and bubbles as previously stated... my guess is meow its your water pump, although serious corrosion in the radiator sure could cause it not to cool properly but at that point id think youd have a leak in your radiator...
 

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It's a 79, so how old is the water pump? and radiator? How well has your coolant maintenance been?

FWIW, i think the proper t-stat on our vehicles are a 190-195degrees
 
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