351 overheating

Hi i have a 65 mustang i did a 351 swap in the new motor was a reverse rotation timing case cover on it and put all winter i ran the reverse rotation pump in standerd rotation. Now that it is gettin wam it is starting to overheat so i build a idle pully n bought a new fan n flat pully to run the pump in reverse rotation. Now it over heats worse than it did when i was running the pump the wrong way? Y is this? Is it a proplem with thermostat now that i changed the rotation?  It never used to overheat at night but now it overheats if it idles at nite or if im going slow threw town. It has a 3row alum radiator and a 1500cfm asist electric fan in it.  

is everything turning the PROPER direction ...


the belt turning the proper pump, mounted on the proper timing cover..  turning the proper fan.. all in the proper rotation?????????????

i am lost...

list parts individually

timing cover...   regular or reverse rotation

water pump .. regular or reverse rotation..

belt drive...   regulator or reverse rotation.

fan blade... regular or reverse rotation..

fan clutch ... if equipped.. regular or reverse rotation.. there are differences inside ...



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thermostat..   160,   180,    192...      or just removed..

do you have a working bypass hose? from the thermostat housing to the water pump???

do you have a fan shroud...

does your radiator cap actually hold pressure????

how much percentage of coolant to water do you have... 50/50 or 70/30??  or straight water..

if you hold a shop rag .. in front of the radiator.. when you rev up the motor.. will the shop rag be pulled tight to the front of the radiator because of the suction created by the cooling fan at fast idle.. or faster???

if you have an aluminum radiator..    can you with the engine off.. wave a drop light between the fan and the radiator while looking straight trough the cooling tubes.. can you see the LIGHT..

why do i  ask this..  there have been instances... where the Oval radiator tubes have had so much pressure applied that they have tried to become round. crush the fins and squeeze together and block the air flow that removes the heat...???

do you have the head gaskets on properly..   one lower corner of the head gasket has a square corner that is totally visible when the heads are installed...  its only one of the corners that has the corner sticking out..  which end is it visible.. on both sides...   they should be on the SAME end of the motor..    you tell me where they are.. i will tell you if the head gaskets are both on in the right direction..

do you have any pictures of the front of your motor.. ???? use photobucket to post them here..  use the 4th link down...

lastly.. does the coolant actually circulate through the radiator when the thermostat is open..  

I know sorry I worded that really bad.....
The timing cover is reverse rotation
The water pump is reverse rotation
The fan is a 6 blade reverse rotation flex fan
The belt I just modified by making a idler pulley to run the pump in reverse rotation
There is no fan clutch
There is a 180 thermostat
There is no fan shroud my cap does hold pressure
The coolant is 50/50 mix
I can't fit a drop light between the fan and radiator but I fit a LED light  between it and can see the LED bulb
I can put a one of those blue shop rags on the radiator and it stays by itself at idle
The corner of the head gaskets are visible only on the front of the motor on both sides
I'll take pics of the motor tomorrow after work and post them
And It looks like its flowing when the caps off The radiator when it's running
Also I only have 1 1/2 inches from the closes part of the fan blade to the radiator

One question I have is why would the pump cool better when I had it turning in a standard rotation when it was a reverse rotation pump? I also was using the original 65 4 blade fan from the 289 when I had the pump running the wrong way . Is it possible that my thermostat is sticking or not working properly because rust from the block was broken loose when the rotation was changed and is making it stick. Idk I might be way off on that i was just wondering? Thanks for the reply  

Ok yesterday i pulled the thermostat out of the car and ran it all day and the hottest it got in traffic was 205 then 210 when i turned the car off. Is this 2 hot for it to run? Also im using a mechanical sunpro gauge now insted of the factory electric one so also i am wondering are they more sensitive to showing changes ?  

Also i wanted to mention to fit the motor into the car i had to use a set of just painted headman swap heads. Now there is only 1/2 an inch of clearance from the headers to the shock tower. Could the fact there so close and not heat wrapped be causing the heat from them idleing in traffic to drive up the temp?  

hand held infrared thermometers are cheep..

this is in stock at many parts stores..
OEM/Non-Contact infrared thermometer - Temperature range -31 to 689 degrees Fahrenheit
Price: $29.99 Part Number: 25245   harbor freight has versions for a few bucks more.. and for almost double. but you get 1100F max with the higher priced units..





now.. when it gets to 205F... is it loosing coolant.. blowing off steam...

205 F is NOT hot on a car... 245 and up is HOT... if the cooling system is working properly..

do you have at least 50% coolant..  and less than 80% coolant..  100% coolant does NOT have the ability to pick up heat and move it to the radiator to be removed by the airflow around the tubes..


without a thermostat.. the coolant will pass through the radiator and engine faster and faster.. it will not stop in the radiator long enough to cool off..  

No it doesn't blow off any coolant since I swapped the pump rotation to the proper rotation. Now it has 50 50 mix and I have the radiator filled completely . I'll check on the heat gun to see what it reads in the next couple days.  

The temp gauge is reading right and it doesnt get over 210 in town so i think im gonna try puttin in a 195 thermistat and see what it does.  

YOU NEED TO HAVE A FAN SHROUD! you need to have it other wise that belt driven fan will just pull air from where ever it can rather than concentrating the air through your radiator and on to your motor.  

Shrouds make things more efficient by getting all air pulled through the radiator instead of around the vicinity of the radiator.