347 RUNNING HOT

Mstng93SSP

You have a nice rear end there Dave.
15 Year Member
Nov 29, 1999
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My personal opinion, the Mishimoto fans suck! Never worked on my car, always ran hot. Now I have Mishimoto radiator and contour fans. Even with the turbo and the weather and heat here in Hawaii I NEVER...EVER run hot.
 
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FastDriver

My dad had a bra
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Bud, I just went through the same thing. In my case, I believe in was a confluence of factors:
1) Added missing lower radiator air deflector
2) Underdrive pullies (Crank & water pump/stock fan) reduced both airflow and waterflow <- this was the big one for me and brought 230* temps (measured at T-stat housing with IR thermometer) down to normal. Your pullies look stock-ish from the pics, but I'd measure and verify if you don't know for sure.
3) The gauge did not read accurately. I had a spare cluster I swapped in and saw it drop by a bar to where I'm used to seeing foxes run
4) Removed the anti-freeze, added water wetter <- adds thermal capacity/transfer
5) removed thermostat <- increases water flow & removes the thermostat & air-bubbles as possible/likely problems.

Now that I've seemingly solved my issue and the car wasn't getting warm enough in 80+ degree weather, I'm reversing the things I didn't really like doing. I just reinstalled the themostat (185*), tonight. I plan to flush out the water wetter & add anti-freeze back in soon.

If you want to solve this problem, you'll need to start eliminating the hypotheses laid out in this thread, one-by-one. New parts, especially aftermarket designs don't equate to good parts. A confirmed cooling issue pretty much comes down to airflow, water flow, thermal capacity or mechanical trouble (head gasket leak/flipped, cracked cylinder, coolant passage blockage). In your case, you can eliminate the airflow concern by ensuring no blockages to the radiator, removal of the shroud everyone is warning you about, ensuring the proper air deflector is in place, and cruising at 50+ mph. I'm glad your taking your temps with an infrared thermometer, but are you jumping out of the car to verify this on the hwy? Maybe I missed something.
 

manicmechanic007

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The fact that the overheating was present with your old fan setup leads me to believe you have insufficient radiator/coolant capacity
And/ Or
Keep in mind that the coolant must remain in the radiator for long enough to get cooled
 
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bird_dog0347

still married haven't seen testicles in years
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The SVE radiator is plenty for your car, I have one and it's fine. I too believe your issue is the fans, more specifically the shroud that is blocking air flow at driving speeds when the fans themselves wouldn't be able to do much. I used the Mk VIII fan on my car but like most people have said the Contour fans work very well and have better clearance. If the air is blocked from flowing through the radiator then your cooling will suffer, and with those fans it doesn't look like there is much flow when driving. In fact I'd bet that shroud design is why it will stay at temp at idle but overheat while driving.

As a test, you could remove the fans and go for a short drive (before it gets all the way up to temp) and try to stay moving the whole time.
 

96pushrod

I think they're a little easier to get off
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Keep in mind that the coolant must remain in the radiator for long enough to get cooled
This is one of those things that really needs to die. Coolant does NOT need to stay in a radiator longer to cool, that is not true. Coolant staying in a radiator also means it’s staying at the source of heat, ie the engine. Never in history has less coolant flow through an automotive cooling system led to cooler temps.
 
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FastDriver

My dad had a bra
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This is one of those things that really needs to die. Coolant does NOT need to stay in a radiator longer to cool, that is not true. Coolant staying in a radiator also means it’s staying at the source of heat, ie the engine. Never in history has less coolant flow through an automotive cooling system led to cooler temps.
Agreed, but have had this argument too many times. Faster moving coolant through the radiator means that it does not stay in the radiator. If it 'sat' there, it would drop in temp, compared to the water behind it, and that would reduce the temp differential vs. ambient/outside air temps. Less temp differential means that less thermal transfer is happening to ambient, which is a bad thing if you're trying to get heat out.
 

rednotch

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Thank you everyone for taking the time to post your suggestions!
I just wanted to clarify that everything cooling system related is brand new as I replaced it all when I rebuilt the engine.

A lot of you are focused on my electric fan/shroud setup as being the issue, I mentioned earlier that I had the exact same issue with my stock clutch fan/shroud combo. I decided then to upgrade to to the LMR aluminum rad and add the fan/shroud combo. I have a Ryobi laser thermometer and seem to get erratic readings when I check various points, I have one at work that seems much better, I'm going to bring it home this week to compare.
The Holley coolant temp sensor is mounted as per the instructions in the metal tube from the front of the intake manifold that runs to the heater core, never mentioned anything in the Holley instructions of having to calibrate a temp sender.
Timing was checked and verified as per the Holley instructions with a timing light at 10 degrees.
Ill make this dead simple for you for the least amount of money... go buy a pack of radiator ties. Dismount your fans from the shroud, remount the fans without the shroud using the ties... Go drive it... be amazed. Your old combo could of had a shot fan clutch and a clogged up radiator, still doesn't change the fact that fan design was made by a moron and sold as a performance upgrade when it isn't

that shroud blocks air flow threw the radiator, you can literally cool a moderate 5.0 with a tiny Honda radiator that's half the size of stock if you have the air flow...
here's just a few examples of that pos fan combo causing the problem, ones a damn near stock car..

View: https://www.youtube.com/watch?v=qaACmWqPNlk


View: https://www.youtube.com/watch?v=hL9YyG7HbEs&t=802s
 
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fasterthangas

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Agreed, but have had this argument too many times. Faster moving coolant through the radiator means that it does not stay in the radiator. If it 'sat' there, it would drop in temp, compared to the water behind it, and that would reduce the temp differential vs. ambient/outside air temps. Less temp differential means that less thermal transfer is happening to ambient, which is a bad thing if you're trying to get heat out.
False! Allowing the coolant to sit in the radiator causes hot spots in the heads and passages. I live in Phoenix and a high flow water pump has helped bring down my coolant temps on every Mustang I've owned. My recipe in the past has been:
Contour fans
High flow water pump and high flow T-stat (Robert Shaw) 195*
Water Wetter and straight distilled water
A 2 row radiator with 1" tubes
Installing a '97 A/C condenser in my 94-95 cars as it's less fin dense thus flowing more air.
Lowering fan ON/OFF temps in the tune

My latest build is turbo'd. I'm running the stock SN radiator and fan.
A high flow water pump and high flow 195* T-stat (Robert Shaw)
Water Wetter and distilled water
'97 A/C condenser
Lowering fan ON/OFF temps in the tune
After 3 back to back pulls; the car hit 210* and cooled down very quick at cruise.
This is also with a 3" thick intercooler out front.
I have yet to run the A/C which will be the real test.

These are things that I've datalogged and did real world testing in outside temps as high as 118*.

I can tell you from experience that if I go back to a standard water pump and T-stat; the car will run significantly warmer.
This is fact and not conjecture.
 
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Mstng93SSP

You have a nice rear end there Dave.
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If the fan/shroud combo is the Mishimoto, return it. It is junk. As I said earlier.... I had a brand new Mishimoto fan setup. I could NOT keep my car cool, not at all. I was constantly at 210 to 220 just cruising around. I sent that junk back and got a refund. I put on dual contour fans with the mounting kit from LMR and even in traffic I almost never get over 200 degrees and I run a 180 degree thermostat.
 

mustystang

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I think you guys are almost agreeing. I think you guys are arguing about 180 vs. 195 tstat. There is a sweet spot. I know others who say 195 tstat actually runs cooler, because of some extra time in the radiator. I think at 180 tstat is open all the time. Sometimes during driving there needs to exist a time for some heat to be pulled away from the engine and cooled before returning. High flow water pump also helps by keeping things moving. Most aftermarket water pumps have somewhat increased fin design based on advances in technology. So by using a 195 tstat you also agree that sometimes coolant needs time to chill, otherwise you would be using a 180 degree tstat. If a stuck open thermostat was extremely benficial, everyone would be using stuck open thermostats from the factory and they would be stuck open all the time. In order to benefit from a 180 degree thermostat you need corresponding mods that would make it beneficial.
 

fasterthangas

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I think you guys are almost agreeing. I think you guys are arguing about 180 vs. 195 tstat. There is a sweet spot. I know others who say 195 tstat actually runs cooler, because of some extra time in the radiator. I think at 180 tstat is open all the time. Sometimes during driving there needs to exist a time for some heat to be pulled away from the engine and cooled before returning. High flow water pump also helps by keeping things moving. Most aftermarket water pumps have somewhat increased fin design based on advances in technology. So by using a ou also agree that sometimes coolant needs time to chill, otherwise you would be using a 180 degree tstat. If a stuck open thermostat was extremely benficial, everyone would be using stuck open thermostats from the factory and they would be stuck open all the time. In order to benefit from a 180 degree thermostat you need corresponding mods that would make it beneficial.
The 195° t-stat opens later to allow the engine to get up to operating temp. Folks pass on the myth that these cars need to run as cool as the old carbureted engines. This is not true. On the 94-95 cars; the low speed fan comes on around 220° from the factory. Just a FYI for everyone.
 
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FastDriver

My dad had a bra
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So, guys... relatively easy to test yourself. Pull out the t-stat and see what happens. Assuming your radiator has more capacity than it's already providing, the engine will never get to normal operating temps. I can personally confirm having recently done this - see my build thread on Black Jack.

On the note about what t-stat to select, this one is reasonably straightforward, too. The advantage in acceleration is going to the lower temp t-stat, because the EEC-IV, or at least the A9L, pulls timing at higher temps.

The best reason I've heard to select a 195 is based upon the fact that the oil will reach the boiling point of water, which allows water, the natural byproduct of combustion, to be boiled off and evacuated from the oil. Oil typically runs ~20+ degrees hotter than the coolant, and of course, in certain parts of the engine it will run hotter than its measured temps. Take away? Oil reaching designed temps is a good thing for longevity.
 

fasterthangas

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So, guys... relatively easy to test yourself. Pull out the t-stat and see what happens. Assuming your radiator has more capacity than it's already providing, the engine will never get to normal operating temps. I can personally confirm having recently done this - see my build thread on Black Jack.

On the note about what t-stat to select, this one is reasonably straightforward, too. The advantage in acceleration is going to the lower temp t-stat, because the EEC-IV, or at least the A9L, pulls timing at higher temps.

The best reason I've heard to select a 195 is based upon the fact that the oil will reach the boiling point of water, which allows water, the natural byproduct of combustion, to be boiled off and evacuated from the oil. Oil typically runs ~20+ degrees hotter than the coolant, and of course, in certain parts of the engine it will run hotter than its measured temps. Take away? Oil reaching designed temps is a good thing for longevity.

I'll add to this. A t-stat is not an opened or closed deviced. When the coolant reaches operating temps; the T-stat acts as a valve by slightly opening and closing as the temps change. This is how the T-stat controls coolant flow.
Some famous engine builders along with the manufacturers have found that there is power to gain by running slightly higher coolant temps than the old days. All of these things can be verified by a simple Google search.
On a side note; Ford had issues with the old 427 FE engines running warm in the late 60's to early 70's. Ford's fix was a cast iron high flow water pump.
 
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96pushrod

I think they're a little easier to get off
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Some of you have bad information I guess (96 pushrod)
Take your thermostat out and watch it overheat
As far as high temps and performance
Why do you suppose a 69 Boss 302 calls for a 214 degree thermostat?
That has nothing to do with it staying in the radiator, it’s the thermostat helping keep pressure in the block reducing hot spots.
 
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General karthief

wonder how much it would cost to ship you a pair
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Some of you have bad information I guess (96 pushrod)
Take your thermostat out and watch it overheat
As far as high temps and performance
Why do you suppose a 69 Boss 302 calls for a 214 degree thermostat?
The 214* stat was for the emissions, higher temp, cleaner burn.
The low temp stat (160-180*) was earlier, pre emissions cars, no stat was a drag racing thing in the early days.
The early carb'd cars also suffered from vapor lock mostly due to the proximity of the fuel pump and lines, too close to the engine, poor air flow out of the engine compartment or 'dog house' for us old timers, when sitting in traffic.
 

FastDriver

My dad had a bra
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Some of you have bad information I guess (96 pushrod)
Take your thermostat out and watch it overheat
As far as high temps and performance
Why do you suppose a 69 Boss 302 calls for a 214 degree thermostat?
I did this 2 days ago. I reinstalled a 185* T-stat after not running one. Temp gauge went from bottom to mid gauge.
 
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