Definitive Heating/Cooling Theory/Troubleshooting Thread

[Cupid 10]

I'll start by saying that I’ve searched the far corners of the Internet/Blogs/WebPages/Forums, etc. and have found that a lot of people have problems with high temps in their Mustangs.

Quite naturally, I have problems with high engine temperatures as well.

I'm interested in your build, problems that you are having/had, but most importantly, how you solved them.

Here's mine:

351 C, bored .030, 12* btdc

Eddy RPM Heads, Air Gap, 1407 Carb, 7168 Cam

Flow Kooler, Napa 197 Thermostat(180*), Autometer Digital Gauge

Champion 2 Row Radiator (RAD29; CJ Pony), + Aluminum Shroud w/16†2500cfm electric fan

My saga started this summer with my temp gauge hitting 220* and beyond. This was sitting in traffic. Ambient temps 80-95* outside.

Swapped the thermostat to the Napa 197.

It worked somewhat. The car could idle all day around 181*. As soon as I’d hit the road temps would shoot up to 210*+. Shot the neck with an infrared gauge, it showed a 15-20* temp difference. (Note: I shot it while idling a bit in the driveway) Faulty gauge!

Swapped to the Autometer gauge. Thought this was it.

Took it on the highway again. Temps shot up to 210*+ again. But I would press in on the clutch and let the car coast to a stop…..I actually saw the temps drop as soon as I’d let off the throttle and coast to a stop. Must be a waterflow problem, right?

Swapped to the Flow Kooler last night.

Attempted to burp the system. It floated around 181* in the driveway. As soon as I put the cap on, the temp started rising. When I took off, within seconds (literally) the temp hit 200*. As I drove down the road, it dropped to about 194*.

If the car runs around 190-195*, I’d be satisfied, especially since it’s a 351 C that has been bored.

I think I’ll attempt the burp process again, since the temps climbed rather quickly when I backed out of my driveway (incline).

Note: I checked for a combustion fumes in my coolant to no avail. I’ll try this again while burping the system again just to be sure.

Thoughts?

[Cupid 10]

Yes, I do have a spring in my lower radiator hose... :-)

[LoneWolf2U 136]

A couple of questions, Is the brass ring under the stat?

Are you using a RobertShaw/Flowkooler 333 stat?

What fan are you using, is it shrouded?

 

If no to eather questions than that is part of the problem.

 

Running a C engine REQUIRES a special stat with the brass ring installed.

Without it you will run hot and have fluxuating temps.

 

My set up works great in 100* temps.

I have the brass plate with R/F 333/180 stat, Coolant is pumped by a high flow aluim waterpump thru a stock 24 in 3 row rad.

Air is being drawn by a clutched 7 blade factory fan with a shroud.

It will sit and idle and reach approx 185-190 sitting still in the driveway.

Out in the real world of driving while moving it stays at 185 running down the road. In stoplight traffic I can watch the temp slowly creep upwards while waiting at the light (mostly behind someone not if I'm the first car and open air infront of me) But the temp will drop back down to 185 after traveling less than 200 feet.

As of yet it hasn't gotten hot enough to engage the fan clutch while sitting still, It may however after I make up the ac lines and charge the system so the ac will operate as it will be drawing more heated air from the condenser at that time.

[Cupid 10]

Yes, I have the brass ring

No, I do not have the RS thermostat. I've searched far and near....nobody has one for sale. Flowkooler has had them on back order for about a year. Apparently the manufacturer is redesigning them. I have the Napa replacement(197; 180*). If you have an extra, I sure could use one!

I took the aluminum shroud+electric fan off today. I put a 6 bladed flex fan on it without a shroud. It made a significant difference at speed. 190ish standard versus 220ish, while running a/c. At idle, it hovers in the mid 190s. I'll order the shroud tomorrow.

[Cupid 10]

Where is your temp sender located? On the pump or by the water return neck?

[1969vert 55]

You might not have a big enough raidiator..

I have a 24" 4 core in a 302 ac convertable and it will idle all day long in texas heat with ac also 18 flex fan with shroud..

Also have a 393 with 24" 3 core fan shroud and 18" flex on it..and when I mean the heavy cooling fan not the small bladed fan that is about 20 bucks.. No cooling issues here..

What width is your raidiator?

I run mine like they should be run.. and they dont overheat...

 

 

When I first got the convertable it had a 20" raidator 2 core it didnt like texas.. overheated idleing with ac on.. changed everything out and have not looked back..

Edited July 7, 2012 by 1969vert

[LoneWolf2U 136]

Where is your temp sender located? On the pump or by the water return neck?

 

Sender is in block near stat, The napa part 197 is close to R/F stat as the bottom hat is 11/16 to cover the hole in the brass ring so it should work.

[Cupid 10]

What width is your raidiator?

I run mine like they should be run.. and they dont overheat...

 

I have the 20" 2-core radiator. Really the same size as stock. Just in aluminum. Apparently a 2-core aluminum radiator cools better than a 4 core copper radiator.:001_huh:

[1969vert 55]

Its all about transfering heat... 20" two core has less surface area to exchange heat vs 24" four core.. More tubes more exchange ... aluminum is more efficent vs brass So a 2 core aluminum is better than a 2 core stock brass.. Its a ballence between heat and removal.. Engines generate more heat rolling down the road than setting still.. you could also check you timing.. to low will heat up a motor also.. check your temp in and out vs another car see what the delta temp is..

Edited July 7, 2012 by 1969vert

[Stevewr54 12]

If you're not running a vacuum advance type distributor you will have a terrible time

with heating at cruise. When you start the combustion too late in the cycle the

exhaust valve will shut before all the heat is out of the engine. No amount of band-aid's

will fix this. You will also a gain in fuel mileage and response. It's just amazing what

those Ford engineers know. I learned the hard way,too. Hope this helps, Steve

[Cupid 10]

I am running a vac adv on it. I'm at 12* btdc Too much more will give me hot start problems.

 

@ 1969vert: I agree with you on heat exchange and surface area.

 

While I'm waiting on my shroud, I think I'll rig the electric fan up as a pusher to augment my direct bolt on flex fan.... Just to see what happens.

 

Might have to go with a larger radiator.....ugh....

[Cupid 10]

Didn't work. So with more airflow via the electric fan(in park) it still initially gets to 181 and hangs out. As soon as I take off it climbs to the upper 190s. When I turn the A/C on, it jumps to 220ish and stays there. You would think that just maybe the pusher was blocking airflow to the radiator, but even without it in place, the standard fan produced similar results.

 

Other thoughts: I would assume (from outside looking in) that I have a freeze plug knocked inside of the block... I doubt that because I put about 4-5K miles on the car already. Yes, the temps still got into the 200s, but it was manageable. I "upgraded" my radiator to try to keep the temps down (It was a Cheap Summit Brand), but it was bigger. Most things point to my stock size 20" as not having enough capacity to keep the motor cool.

 

Hey...it is 100* outside today, but I'd like to drive the car no matter what the temperature is.

[1969vert 55]

Had electric pusher when my 351w was supercharged.. street driving was out of the question..Didnt cool off that motor till I put a fiberglass flex and electric pusher.. Dumped supercharger ( belt eater) and just added more nitrous.. Electric pushing looses 40% of there scfms compaired to pulling... just saying..the best fan is stock or extra hd cooling stainless flex 18" or bigger I think stock is around 18 1/2 or 19" and yes a small electric pusher can block off air flow to condenser and radiator.. It will only flow so much air it can block free air from entering the radiator....If you were around texas I would give you a 20" stocker I have laying around.. everything of mine will have a 24".. The raid in my vert years ago was 400 smackers.. Still check the inlet and outlet temps with a gun and see if it is cooling enough there should be a drop in temp from top and bottom..

Edited July 7, 2012 by 1969vert

[Cupid 10]

Okay, took it out on another run. Turned on the A/C and took these:

 

Gauge: 220*

Temp Sending Unit: 215*

Neck: 193*

Return: 180*

 

 

I turned off the A/C and then I ran it pretty hard to get the temps up as high as I could by going through the gears. It hung out around 218*. Turned on the A/C and drove normal for about 3 miles back to the house.

 

Left the A/C on, popped the hood and got more measurments.

 

Gauge: 231*

Temp Sending unit: 230*

Neck: 206*

Return: 192*

 

So it looks like i'm getting 13*+/- 2* cooling through the radiator. Is that good?

 

I'm trying to narrow down whether it's the cooling capacity of the radiator or something is wrong with the motor, e.g., freeze plug in block or coolant bypass/thermostat isn't working correctly.

[1969vert 55]

Will check mine tonight after work...but it looks like the radiator with those numbers.. you should have a bigger temp drop across the radiator..

[1969vert 55]

/checked my truck after work 120 to 137 in ( t-stat working)

110 to 111 at the water pump...are you sure you have good flow ?

[Cupid 10]

Huh? What kind of motor and cooling system do you have in your truck?

 

137* can't be good engine operating temperature?

 

Regardless, I think I have pretty good flow. Just looking in with the cap off, I see a rush of fluid from left to right. It's a lot better with the Flow Kooler and new thermostat I just installed.

 

I have an old 24" (I think) that I took off. (pretty beat up Universal Summit Racing Brand) I'll try that tomorrow to see if there is a difference in cooling.

[1969vert 55]

diesel 95 1 ton the t stat cycles and keeps it cool.... you are right about 137degs but the thermostat is keeping 195 deg in the motor...just think of it as a control valve for temp it will keep temp at the desired temp which is 195 it only allows so much coolant out ... so the radiator will always show a lower temperature ...so back to your motor ... if you want to burn it up keep going forward... if you want to enjoy your ride pm me and and we will try to find out what is going on so you can burn some rubber with no problems..:blink:

[Cupid 10]

I definitely can't afford to burn it up. It's only reached 220 twice and 230 once and I don't plan on doing that again!

 

I have two or three ideas. PM Sent.

[LoneWolf2U 136]

The 20 inch rad is too small. Your seeing a rush of coolant with cap off at idle means that the system is operating correctly IE;moving enough coolant.

The problem is the amount of area that the system has to disapate the heat is too small. The amount of coolant moves thru the rad too quickly to reduce the heat before it reenters the engine.

Hell a 20 in stock rad had a hard time cooling a 6cyl in hot times.

[miketyler 15]

Did you make a change that brought on these temps or did this start gradually over time? I have done a lot of research and trial and error on my 340 Cuda with its hot running temps. I have read several times that aluminum isn't better than copper/brass - its cheaper. Actually copper/brass has an edge in heat dissipation but aluminum is cheaper, lighter, and has become the standard construction today. There are other variables in radiator design and things like tube size, placement, fin design all play a role and these can give aluminum an advantage over copper/brass.

 

I dont think your choice in construction of radiator is the problem though. What about all the other stuff? I assume you have checked for vacuum leaks, fuel mixture, exhaust restrictions, etc ?

[Cupid 10]

Hey guys,

The plan is to to with a restrictor plate and a larger radiator. I'm looking at $400. If you are in the market for a *new* 20" aluminum radiator and shroud that has 10 miles on it, let me know...

 

Is the restrictor plate extreme? Yes....but I don't ever have to worry about my engine block heating up unevenly again and I don't have to worry about finding a specialized thermostat again.

 

 

 

http://www2.cougarpartscatalog.com/waterrestrictplate.html

[buening 63]

My zero-issue/fool-proof cooling system is a 19x27.5" Northern (also Summit brand) crossflow radiator (relocated battery needed or trim battery tray), hi-flow thermostat, Flowkooler hi vol aluminum pump, and any decent electric or mechanical fan with shroud. The radiator is the widest that will fit between the frame rails, and the core fills the entire opening with the end tanks outside the radiator support opening.

 

I am using an aluminum shroud with a Taurus fan and DCControls fan controller, but it won't clear engines in their factory location. I had zero cooling issues with the junk Zirgo before it, proving that the size of the radiator was large enough to minimize the need for a large CFM fan. The DCControls fan controller only pushes the Taurus fan 25% speed even at 100°+ ambient temps with A/C on.

 

I have a 25° temp difference at the inlet and outlet of the radiator using a meat thermometer. Thread with pics: http://www.1969stang.com/mustang/forum/showthread.php?t=10556

 

Pics of my fan install: http://www.1969stang.com/mustang/forum/showthread.php?t=8388

[Cupid 10]

Can't believe I haven't seen that post. I'm looking at radiator with a 24" wide core. I did see one that was 33" end to end. Didn't want to do much with modifying it. Are you able to run the A/C in 100* weather, at the red light?

[buening 63]

The core itself is about 18x23 IIRC, but its been awhile since I measured. There is some wasted space at the top and bottom where the downflow tanks would be, but with a shroud it still pulls air from these locations. A crossflow is more efficient by design from what I recall. You can also get dual and triple pass radiators to improve the efficiency. I'm running this particular one: http://www.northernfactory.com/storefrontB2CWEB/itemdetail.do?action=prepare_detail&itm_id=15441&itm_index=3

 

Attached is a few pics from years ago when I was test fitting the radiator.

 

Yes on running with A/C at red light. Like I said my fan barely spins, meaning the radiator is overly efficient in my case. My motor is a standard 351w with cam/intake/carb upgrade, nothing special. The only time I had issues with my cooling was when my zirgo fan connector came unplugged and it crept up to 210° cruising from stoplight to stoplight. The zirgo without a shroud did the job, I just wanted to pretty it up with a shroud and if I was going that far, why not beef up the fan and go with the Taurus? Had to move the motor back though, compliments to my Ron Morris-copied motor mounts.