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1967 mustang coupe v8 289
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Discussion Starter #1
got myself an infrared gun. after driving about 10 miles in 80 degree weather. 67 with 289, 24" aluminum 3 row rad. stock fan and shroud. hoses were around 180-200F, heads were about the same. top of manifold was 215-230, exhaust manifold was 380-close to 400 degrees. couldnt get a reading on the radiator itself because it was just reflecting the light. i'm pretty sure thats too high? radiator and thermostat are new. just installed it myself. what did i do wrong? how do i fix?
 

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215-230 is not that bad. It's about what mine runs in the middle of the summer. If it's not spitting coolant out of the overflow, then you should be fine.
When you fill the rad, don't top it off. Only fill it til the coolant is just over the row ends to give it room to expand when it heats up.
 

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1967 mustang coupe v8 289
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Discussion Starter #3
215-230 is not that bad. It's about what mine runs in the middle of the summer. If it's not spitting coolant out of the overflow, then you should be fine.
When you fill the rad, don't top it off. Only fill it til the coolant is just over the row ends to give it room to expand when it heats up.
i shouldnt be worried? i read somewhere that if it reaches 210, it will overheat. i never read the temps of my old radiator but it would fill the overflow tank all the time to almost full. the gauge is always reading past H but when stopped at a red light and with the heat on full blast it would come down a tad. i'm planning a long trip soon. i dont want to get stuck overheated
 

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The temp that matters is the temp of the coolant and not the surfaces. The closest you’ll get for a temp gun is by reading the upper hose.

You’re fine. A 210* F temp is is well within the operating window for your engine.
 

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Water boils at 210. Your minimum running temp for the engine is 190. The coolant extends the boiling temp much higher than 210, so 210 isn't hot... it's more like "normal".
As I mentioned earlier, if it's not spewing out of the overflow, then it's not overheating.
If you're filling the radiator to the top, then your overflow tank will fill up because the coolant has nowhere else to go when it expands.
 
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For every pound of pressure your radiator cap puts on it, it raise the boiling point 4 degrees. Its when it turns to steam and expand 1600 times that things start getting damages. Aluminum heads will warp if you get them too hot. Don't ever let the gauge go all the way to hot or you could warp the heads.

For fun take your infrared gun and see what the difference in temperature is between the upper hose and the lower hose. That way you will know what is normal for your car.
 

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Scott. You did not mention what your temp gauge reading indicates. Is you car showing signs of recent overheating to cause you to measure temps with IR gun?
 

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1967 mustang coupe v8 289
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Discussion Starter #9
Scott. You did not mention what your temp gauge reading indicates. Is you car showing signs of recent overheating to cause you to measure temps with IR gun?
i've never had it overheat even with the old radiator. i replaced it because it looked old and beat up and was rusting and just wanted to upgrade. i got the gun because it felt hotter than the old one did. and i just wanted to be safe. the temp gauge would go just before H about 30 seconds after cold starting. then past H as soon as i get down the drive way and would stay there while driving until i stop at a light and throw the heat on. then it would stay on or before H. sometimes not going any lower than H. i'd be comfortable if it would stay below that on the gauge but i guess thats not possible these days
 

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Normal operating temperature for the SBF in an old Mustang is 200-210* or so. A 195* thermostat is not fully open until 208-212*. A "hot" running engine is around 230-235*... those are temps that you'd expect to see at Donner Summit with a full load and 240* is the start of "moderate" overheating (A 50/50 mix of ethylene glycol coolant under 15psi will boil around 264*... a bit higher if your drop back to 40% antifreeze) and 260* is where the fun begins.... mainly from the perspective of excessive OIL temperature and failure of head gaskets.
 

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1967 mustang coupe v8 289
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Discussion Starter #12
For every pound of pressure your radiator cap puts on it, it raise the boiling point 4 degrees. Its when it turns to steam and expand 1600 times that things start getting damages. Aluminum heads will warp if you get them too hot. Don't ever let the gauge go all the way to hot or you could warp the heads.

For fun take your infrared gun and see what the difference in temperature is between the upper hose and the lower hose. That way you will know what is normal for your car.
took some temps today. top hose is 190-210 bottom hose is 80-90. top of manifold was about 250-260, exhaust manifold was above 500. is that normal? especially the bottom hose being so cold. which areas matter the most as far as temperature
 

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took some temps today. top hose is 190-210 bottom hose is 80-90. top of manifold was about 250-260, exhaust manifold was above 500. is that normal? especially the bottom hose being so cold. which areas matter the most as far as temperature
Bottom hose being cooler means your new radiator is cooling. The coolant exits the engine through the top hose, flows down through the rad to the bottom hose to make the journey through the engine again.

I’d agree that looking at your gauge there is an issue but I would say the issue is in the gauge circuit and not your cooling system. Your gun temps would be much, much hotter if it really were as hot as the gauge indicates. Perhaps your sender is bad or for some reason not getting a good ground. Check the connections and meter the sender to see if it’s ok. I don’t have the sender measurments in front of me and I’m about to break lockdown to go out but a search here or perhaps someone with them will post the specs.
 

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That bottom hose reading is more like ambient temperature. Are you sure you shot the hose? Your engine is most efficient at 205 so those upper hose numbers are not a problem.
 

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Discussion Starter #15
Bottom hose being cooler means your new radiator is cooling. The coolant exits the engine through the top hose, flows down through the rad to the bottom hose to make the journey through the engine again.

I’d agree that looking at your gauge there is an issue but I would say the issue is in the gauge circuit and not your cooling system. Your gun temps would be much, much hotter if it really were as hot as the gauge indicates. Perhaps your sender is bad or for some reason not getting a good ground. Check the connections and meter the sender to see if it’s ok. I don’t have the sender measurments in front of me and I’m about to break lockdown to go out but a search here or perhaps someone with them will post the specs.
it's a new sender. it will go a bit below H at idle (stopped at a light etc) then go back over H while driving.
 

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1966 GT Fastback, 289, TKO 5-spd, EFI, 4-discs, TCP coilovers
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Normal operating temperature for the SBF in an old Mustang is 200-210* or so. A 195* thermostat is not fully open until 208-212*. A "hot" running engine is around 230-235*... those are temps that you'd expect to see at Donner Summit with a full load and 240* is the start of "moderate" overheating (A 50/50 mix of ethylene glycol coolant under 15psi will boil around 264*... a bit higher if your drop back to 40% antifreeze) and 260* is where the fun begins.... mainly from the perspective of excessive OIL temperature and failure of head gaskets.
Woodchuck - you have commented on this issue before, but I would like to present my observations to the Committee for further comment.

My objective is "good temperature control", which to me means the overall cooling system should maintain a temperature close to the thermostat setting, give or take Here is my setup:
  • The engine is a moderate 289 (~315 HP) with Edelbrock EFI, Edelbrock aluminum heads, a new water pump and hoses, and Vintage Air A/C (Sanden compressor).
  • The radiator in this car at the moment is a relatively new Champion 19 x 17 three-row downflow aluminum with a 16 psi cap. Therefore, this radiator provides barely the minimum 1 sq in or area per horsepower.
  • The radiator has a 2700 CFM LoPro electric fan and sealed shroud, set to come on at 190 degrees.
  • I just installed of a new 180 degree Milodon high flow thermostat.
  • Note that the A/C condenser is right in front of the radiator and covers probably 1/2 - 2/3 of the frontal area. This is certain to at least block some air flow and also present a new heat load to the radiator when the condenser is hot.
Yesterday was a "normal" hot summer day for here - low 90's, humid,etc. Here's what I saw:
  • With the A/C running and the car at town cruise (45 mph, 2000 rpm, 4th gear), the temperature wandered from 200-205 degrees, depending on engine load.
  • With the A/C switched off (but not for very long), the temperature dropped to 196-199.
  • The Milodon thermostat did not seem to improve anything; in fact, the temperatures seemed a little higher than before (but it was hot outside), so it might actually be making cooling worse by increasing the flow and reducing the radiator residence time.
  • The A/C compressor seems to present an excessive load on the engine. While sitting idling and hot, when the trinary switch cycles to "on", there is a significant growling sound as the engine labors to turn the compressor, and the sound goes away when the switch goes to "off". Also, when fully hot, the starter can barely turn the engine over on restart with the A/C compressor on. Switch the compressor off and everything is fine - starts right up. Is it possible that something is wrong in the A/C, e.g., too much pressure or too much load?
  • The electric fan just runs all the time.
I don't like it - this does not seem like good temperature control to me. However, would any of you be concerned with these temperature readings? What about the A/C compressor engine load issue?
 

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i shouldnt be worried? i read somewhere that if it reaches 210, it will overheat......”
Whom ever wrote that should be horse whipped .

Ford put the stock 192/195 F thermostat in millions of cars. They all ran fine without overheating. The stock thermostat doesn’t even fully open until the coolant temperature reaches 212

225-230 is not too hot for a car that is moving. Personally I like a SBF engine to run at 215-220 F, but in the 220’s doesn’t keep me awake at night.

It can go up a little from there for short periods of time (like sitting at a red light) and not hurt a thing.

Z

PS. I trust a permanently installed mechanical coolant gauge more than I do the I.R. guns, a lot more.

Autometer makes a good one.!
 

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67 coupe, 69 Sportsroof, 86 hatchback
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Pretty much agree with what Zray said. All the temperatures given in the first seem about dead on perfect to me. Don't care what two random guys on the internet say? Google it. "Ideal operating temperature of a gasoline engine". And see if any resulting information contradicts us.
And personally, the second I read that someone is running a lower temperature thermostat than 192-195F in a Mustang I feel it's safe to ignore every word thereafter.
 

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Discussion Starter #20
this thread is 3 months old. i have since resolved the issue. thanks though!
 
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