Cooling System Opinions

Christian Cornwell

Active Member
Aug 31, 2016
86
20
28
Upstate NY
So I just finished swapping a 5.0 into my sn95. The motor came out of a 89gt so I figured I'd post this here. I have a aftermarket Sr performance radiator in the car and an edlebrock Victor water pump on the car. I don't daily the car anymore and always let the car warm up long enough before driving it any. Due to this I don't have a thermostat in the car. I know I'm going to get a lot of people saying the car is going to run too cold which is where my first question comes in, how much of a difference does it make? I know people run without them but just want to make sure there's no problems. I'd rather have the car run a little cooler than too hot. I know that when everything is working correctly that isn't a problem but I seem to have had bad luck with thermostats in the past. If it is super important to run one in there can anyone recommend a good one?

My other question is that I seem to be getting quite a bit of pressure in the upper radiator hose but not all the time. I've read this is normal but it seems like it would be more consistent when it has pressure and when it doesn't. I've burped the system and I don't think there's hardly a drop of air in it. The head gaskets are also brand new so there's no problem with those making it build pressure. The car doesn't get hot and everything heats up evenly as verified with a temp gun but I haven't really drove the car hard. Anyway back to the question part of that section, would a lower pressure cap help me out any? I read that if you run a lower temp thermostat and lower fan turn on temp it's better to drop down to a 13psi cap. I have the cap that came with the radiator it says 1.1 on it which I assume is 1.1bar which is 16psi which is correct for the stock system. Should I drop down to a 13psi cap? If so what is the best cap?

Just trying to make sure everything is good to go on this before I start putting some more miles on it of hard driving. Thanks for the help in advance.
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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polk county florida
Put a thermostat in it, 195° preferably and make sure your 16 lb cap is good.
Test all thermostats in a pot of water on the stove with a meat thermometer, just don't tell your wife.
 
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imp

Mustang Master
Jul 13, 2017
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@Christian Cornwell
I've always heard running without a thermostat can allow too much variation in temperatures within distant parts of the cooling jacket, "temperature gradients" they're called. Undesirable. A low-temperature thermostat is almost as bad as none, as it may prevent the PCM (computer) from entering what is called "closed-loop" operation.

A lower pressure rating radiator cap gains you nothing; it will not keep your cooling system working at a lower pressure. The level of pressure reached depends only on the coolant temperature. The aim of the pressure cap is to prevent it from boiling, which would be a bad thing. The 16 psi cap is intended to allow running temperature considerably above the boiling point of water at 0 psi, while giving protection in the event of boiling anyway, of preventing anything from bursting, and to protect the water pump shaft seal, which is not designed to withstand high pressure. imp
 

Steel1

Mustang Master
Aug 18, 2017
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If your still EFI than put a stat in it, like stated above the ecu will not see engine at operating temp thus causing drivability issues.
If you don't already have one install a good aftermarket temp. gauge.
 
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Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
34,595
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Running too cool in a modern engine can be bad. By not allowing the vehicle to get to proper operating temp, certain components may not get up to proper temp, and as a result not have the proper spec on clearances and such. Also, getting the vehicle warmer allows moisture and contaimants in the oil to burn off. The main issue here is engine longevity.

Modern EFI cars like to operate at 185-205 degrees F. Stock tstat is 195, and this is what you should be running.
 
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Christian Cornwell

Active Member
Aug 31, 2016
86
20
28
Upstate NY
Sounds like the consensus is to throw one in there. Anyone have a good or preferred one? I'll make sure to boil it when I get it. I've got awhile to worry about a wife being mad about it though I'm not even out of my teens yet haha. I did order an aftermarket gauge it should be here any day so I'm not relying on Ford stupid gauges.
Thanks for the help guys!
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
34,595
10,767
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Massachusetts
Negative on water wetter. Mix of antifreeze and water depends on your location. More water unless you live where it freezes then go 50/50

I've had a stant 180 in my car for 20 years that was worked well
 

Christian Cornwell

Active Member
Aug 31, 2016
86
20
28
Upstate NY
I live up in New York so I have to have a good mix of antifreeze in it right around 50/50 is what I run in everything else just wondered if it would make and difference to put a lower mix in then when I park it for the winter switch it out for 50/50
 

imp

Mustang Master
Jul 13, 2017
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Southern states run up to 20% coolant. More coolant means less cooling. Nothing transfers heat better than water.
@a91what

Uh, uh! Liquid Mercury metal, great cooling medium! But, not convenient. The jerks who design Nuclear Power Plants prefer, can you believe, molten Sodium Metal! Contacts slightest bit of water, instantly explodes!

Water really is best. imp