ave a 1990 mustang with hci and an electric fan with underdrive pullies When I first bought the car it ran great and stayed right at 180*. the one day I pulled up to a stop light and stayed there for a bit and it went from 180 to about 200...then it was fine.
It started to happen on and off the car would run hot. Then I had some problems with the tranny and pulled it out rebuilt it put it back in and the only changes I made was I went non lock up. (because before the car was having problems with the lock up converter.After I got it back in the car I drove it around same thing would get hot off and on.
SO I thought it might be the t stat sticking (and it was getting worse cause it would climb to 190-200 almost everytime I drove it ) so I changed it out for a moroso 180* and still the same results
now Every time I drive it the temp climbs to 198-200 and Stays.... CHECKING IT WITH A DIGITAL POINT GAGE and thats also what the gage says.... I ALSO put a new radiator cap and a temp sending unit in and burped the system a couple times I belive I got it but maybe not.... The fan I have turn on early like 150* Flex a lite elec fan
Any ideas?
car A/F is 12.8-13.0
Sorry for the long post only way I could explain it
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1990 Mustang gt:
forged 306, Edelbrock Alum. performer heads, Gt40 upper and lower intake, E303 cam, Cai, Under drive pullys, Mac equal length headers, Off road 2.5in H pipe, built transmission, TCI shift kit, TCI comp converter (3000 stall), 3.73 gears.
Well, to be honest, 190-200 degrees is not hot, in fact thats what that motor should run at. That computer was programmed for a 195 stat and thats where it should run at. I would not worry about it unless it continues to climb. I bet a bunch of 94-95 guys would love for there 5.0's to stay about 195-200 degrees, I know my dad's 94 Cobra runs at 210 most of the time and he lives on the coast of California where its not even 80 degrees outside most of the year.
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Jesse Berger 90 LX, Previous 4 cyl. (Decommissioned, 351W on the way)
H/C/I+Bolt Ons
Best ET: 12.54@106 mph 2001 V6 5 Speed Daily Driver Windstar Intake, Dual Exhuast, CAI, Headers
Best ET: 15.6@88 mph (stock trim)
Not too sure, how long have you been running the H/C/I stuff? As long as it doesn't continue to rise, and your cooling system is in good shape I wouldn't worry about it.
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Jesse Berger 90 LX, Previous 4 cyl. (Decommissioned, 351W on the way)
H/C/I+Bolt Ons
Best ET: 12.54@106 mph 2001 V6 5 Speed Daily Driver Windstar Intake, Dual Exhuast, CAI, Headers
Best ET: 15.6@88 mph (stock trim)
Look at your fan. Alot of aftermaket fans come with a switch so that you can set your fan to kick in at a certin temp. With the new "hci" was the water pump replaced. Depending on the mileage you could see a decent drop in temp.
Along with that whens the last time the fluid was changed? Is it discolored? What I normaly do is run the car with the radiator car off to let the fluid run through the car (it wont over flow until the car is off). If you can see it go down pour some in. Once it's full cap it off. That's if your low.
The temp will stay at 180 because the hood is up, allowing all the heat to evacuate the area.
Does the temp come down when you get moving again? You say it heats up when you stop.
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Ask me why I ran "only" a 13.54.
Member: NMRA Member: White Mustang Registry #362 Member: Fuzzy Dicer
Just thought of this. you have a electric fan but did you or the last guy up grade the stock radiator? If it's the stock one from the factory that thing probley has a lot of gunk in it!
1990 mustang HCI running hot. 
