When I bought my 66 convertible with a 289 about a year and a half ago, it was in poor condition after sitting outside and not being started for 5 years after a rebuild from the previous owner. After I got the engine back in shape it ran great, but the only thing was it was overheating like crazy. It would slowly climb up in temperature to the end of the temp guage and would never come down (even in 70 degree weather and no traffic)
I had replaced the water pump, radiator (3 row), all the hoses with spring enforced ones, multiple thermostats, multiple flushings, added an electric fan..... I was stumped..... Until I realized that too much "antifreeze" or "coolant" actually can cause your engine to overheat because it has worse thermal transfer properties than water alone. So I went from a 50/50 coolant mix to a 15/85 and added "water wetter" and now I run normal. Yesterday I idled for about 10 minutes until it got to about 180-190 degrees, my thermostat opened and dropped me instantly to 160, and then I sat there and idled for another 10 minutes staying around 175. So to anyone who has tried everything like I did..... try increasing your water compared to coolant and adding a "water wetter" type additive to prevent corroding. (p.s. I live in so-cal so I dont have to worry about my motor freezing on me)
I had similar issues, but I replaced original styled 3 row with an aluminum rad and also a high flow waterpump (which I did first with no solution) and now it runs cool except when I idle. I may have to try the water wetter. I'm also am not using a fan shroud, so that may explain my idle problem. I live in Canada, so I do have to worry about the cold
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Early 1965 Mustang Coupe GT clone, Toploader, Bored 0.03" over, Front manual disc, dual 2.5" exhaust, mild cam, Crane roller rockers, RPM performer intake, 625 Road Demon carb, Mallory distributer, MSD 6A ignition, Aluminum Radiator, Edelbrock High Flow Water Pump, some engine bling!!
I thought 50/50 was supposed to be the best mix to keep the engine running cool, wouldn't it freeze in the winter if you ran 15% antifreeze / 85% water?
i usually use the water wetter on all my trucks, which i use for my construction business, and they runb so much cooler, even when hauling huge loads to the dump. I use it on my 68 mustang, all the colling system is stock, and i do run the coolant a bit less of antifreeze, i would say 20/80, and the car runs perfect, never overheats, and i live in southern california.
I thought 50/50 was supposed to be the best mix to keep the engine running cool, wouldn't it freeze in the winter if you ran 15% antifreeze / 85% water?
Well this is the best mixture during winter seasons when freezing is an issue, because it loweres the freezing point of the water. And although "coolant" also increases the boiling point of the water, it doesn't have the same thermal transfer (heat absorbtion) capabilities as water alone. So with a 50/50 mix you are not getting the full cooling effects of just plain h2o.
But water alone is bad for your radiator/water pump/motor because, by itself, it will cause corrosion/build up in your cooling system. Thats one of the main purpose of the antifreeze.... it keeps your cooling system (water pump, radiator, hoses, etc) clean and lubricated.
That is where the "water wetter" comes in. It reduces the surface tension of the water (reducing air bubbles and allowing it to absorb more heat than water alone) and it also has a couple additives to keep your cooling system clean and lubricated.
Thats why after a lot of research I switched from 50/50 to:
85 distilled H2O
15 coolant
and one bottle of "water wetter"
my 67 FB has a 428cj and it kept overheating right up to the point where my head gasket blew out. im still waiting on the time to fix it but im hoping replacing the gasket will help her run cooler. i used water wetter in it before i had problems and it deffinitly seemed to help
Jamie, you didn't mention what Tstat you installed, 180*, 195*?
Jon
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'67 Coupe 289 C4, Candyapple red w/red deluxe int., PS, ext. decor group, light group, foxbody seats.
Next to install> stroked 333, AOD, 9" w/3.50:1, PDB.
'09 Black Warriors In Pink with glass roof - the wifes Mustang.
"If it ain't broke, I haven't fixed it yet" -Jon
I run a 2:1 mix of distilled water/coolant in mine, hasn't cooled it down any, still runs hot for me. I think I need the rad rodded out after sitting for two years.
As for freezing, it depends on the climate. Out there in SoCal, that's not even a worry (I'm a California native, I would know ). Here in E. Texas it could be on some mornings, we get some now and then in the teens and 20's. Up in the Dakotas where it gets ungodly cold, you have to run more like an 80/20 coolant/water mix.
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'67 Mustang Convertible - show car, now my DD
'61 Mercedes 190b - work in progress
'09 Harley XL1200n Nightster
Gone but not forgotten:
'68 Hardtop - my high school DD '02-'05
'73 Mach 1 351CJ - Dad's DD '03-'05
'66 Hardtop - Learned stick on this 4-speed A-code, manual brakes/steering
I run a 2:1 mix of distilled water/coolant in mine, hasn't cooled it down any, still runs hot for me. I think I need the rad rodded out after sitting for two years.
As for freezing, it depends on the climate. Out there in SoCal, that's not even a worry (I'm a California native, I would know ). Here in E. Texas it could be on some mornings, we get some now and then in the teens and 20's. Up in the Dakotas where it gets ungodly cold, you have to run more like an 80/20 coolant/water mix.
Try a 15/85 (85 distilled water) that should cool you down.....
I like the water wetter also. But 15/85 does sound like a good mixture but I guess that it don't freeze in Cali. But I would get a anti-freeze tester to see what my freezing point is at.
Try a 15/85 (85 distilled water) that should cool you down.....
What would be the freezing point of that?
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'67 Mustang Convertible - show car, now my DD
'61 Mercedes 190b - work in progress
'09 Harley XL1200n Nightster
Gone but not forgotten:
'68 Hardtop - my high school DD '02-'05
'73 Mach 1 351CJ - Dad's DD '03-'05
'66 Hardtop - Learned stick on this 4-speed A-code, manual brakes/steering
289 Overheating issue solved!! 
). Here in E. Texas it could be on some mornings, we get some now and then in the teens and 20's. Up in the Dakotas where it gets ungodly cold, you have to run more like an 80/20 coolant/water mix.
