Overheating at idle

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Kenflo

Kenflo

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Hello all, I just finished a complete cooling system overhaul on the car and I am overheating at idle. When I go for a cruise it runs fine and normal temps are observed while moving like 170 on highway and 200 when going slow. When I'm parked and idling it climbs and climbs to 240, than I shut it down and I can hear it boiling over into the recovery tank. This is the new system:
-New 3 core 22" US Radiator
-13 psi cap
-Repo shroud from Classic Industries fan is 1/2 in and 1/2 out
-50:50 coolant
-All new hoses
-180 high flow stat
-5 blade 18" Mopar Performance viscous fan
-Hayden HD clutch
-Milodon high flow water pump
-New hood to rad seal
-New hood to cowl seal
Engine:
-1968 422 cu. in. stroker engine
-Sniper EFI
-Doug's painted headers (not coated)
-Eddy heads
-727 trans and cooler in the bottom tank of rad

Also checked and adjusted timing to 14 advance and 32 total as per my MSD set up as well double checked my idle speed Sniper settings.

Would a 7 blade fan be worth a try? Or maybe electric fan like the Taurus fan set up that I've read about on here?

I'm overheating myself! Just done so much work and disappointed with the outcome, looking for some advice. I thank you all in advance for any ideas or expertise you can add

image.jpg
 
You need to pressure test the whole system. I had the same issue and it was a bad radiator cap. It was new.
 
First, have you 100% verified the temperatures with an IR heat gun? If so, how is the fan driven? The water pump pulley should ideally be a little smaller than the crank pulley.
 
The water pump pulley and crank pulley is from a 73 318 non AC car and on my set up with the crank pulley it is 0.95 underdriven
Water pump pulley diameter
6 7/8"

I do not own a IR gun however I did put my hand on the rad and found no abnormal hot spots
 
Kenflo said:
The water pump pulley and crank pulley is from a 73 318 non AC car and on my set up with the crank pulley it is 0.95 underdriven
Water pump pulley diameter
6 7/8"

I do not own a IR gun however I did put my hand on the rad and found no abnormal hot spots
Click to expand...
I'd sure get one before you do anything. They are a very cheap, yet indispensable tool. It could verify your over heating, OR save you from doing anything unnecessary. .95 underdriven seems like a pretty small amount. But, I'm no expert.
 
I just went through a similar issue though not quite as severe as yours. My fan clutch was the culprit but I see yours is already new.

Head to harbor freight and buy one of these:
Screenshot 2024-07-01 at 11.04.31 PM.png


Then take some readings at various points under the hood.

Another forum member supplied me with some readings from his vehicle so I had some comparison values. I created a table to track and log temps before and after my fan clutch change.
 
Looks like it's time to go buy some more tools!
I will pick one of these up and take some readings
 
What cam specs?

If not using one, use a high flow 180 thermostat. At least remove & test the existing stat. It may not be opening fully. Do not drill holes in the stat; all it does is increase warm up time.
Main problem is pump speed [ & therefore fan ] too slow; makes a BIG difference. Pump should be overdriven 10-20% relative to crank.

More info here: www.stewartcomponents.com
 
Bewy said:
What cam specs?

If not using one, use a high flow 180 thermostat. At least remove & test the existing stat. It may not be opening fully. Do not drill holes in the stat; all it does is increase warm up time.
Main problem is pump speed [ & therefore fan ] too slow; makes a BIG difference. Pump should be overdriven 10-20% relative to crank.

More info here: www.stewartcomponents.com
Click to expand...
I have verified my 180 high flow stat is fully opening with the pot of water on the stove method prior to installing. I did some research on overdriven pulleys and found the only way to get anything overdriven was to change the entire pulley set up to serpentine like the CVF 1:20 set up as the stock overdriven pulleys are super hard to find. I figured I would try the stock non AC Pulley I had as that wasn't really in the budget at the time.
 
if it were me...
put a stock water pump and thermostat in your cooling system. A stock mopar water pump flows 20% more than a GM or Ford. The stock thermostat will keep your coolant in the rad longer.
Get rid of the clutch fan...they operate at about 80% speed at idle due to fluid slip.
Try a little more initial timing. Retarded will put the fire in the heads rather than the cylinders where the coolant will absorb the heat. A good test is to check and see if your headers glow in the dark.
If that all fails..just open the vault and get a griffin muscle car rad with 1 1/4" tubes. Then go find a red light and sit there without worry at an ambient temperature of 90 plus.
 
I would love a dollar for every one of these threads
BS on removing the fan clutch!
non ac pulleys always seems to work for me time and time again big or small block...
Flow cooler water pump regardless of pulley speeds
60% distilled water 40% antifreeze, bottle of coolant conditioner
increase initial timing - What about the engine tune up? sounds like its lean lean
IR temp gun! what's the temp at the base of the carb?
if manifold has an exhaust crossover it needs to be blocked
use the new style mopar radiator cap for systems with a coolant reservoir, no i do not have the pn, it's not on my current pc.
195 stewart components thermostat, here we go down the rabbit hole - if you think this is incorrect then ignore everything else i suggested and good luck
 
j_anderson said:
you are using a non ac pulley? I don’t know the answer but it’s it a different size than a pulley for AC equipped cars?
Click to expand...
According to the factory service and parts manuals there are different size pulleys for AC and non AC cars as well max cooling options
 
SixPaksRule said:
I would love a dollar for every one of these threads
BS on removing the fan clutch!
non ac pulleys always seems to work for me time and time again big or small block...
Flow cooler water pump regardless of pulley speeds
60% distilled water 40% antifreeze, bottle of coolant conditioner
increase initial timing - What about the engine tune up? sounds like its lean lean
IR temp gun! what's the temp at the base of the carb?
if manifold has an exhaust crossover it needs to be blocked
use the new style mopar radiator cap for systems with a coolant reservoir, no i do not have the pn, it's not on my current pc.
195 stewart components thermostat, here we go down the rabbit hole - if you think this is incorrect then ignore everything else i suggested and good luck
Click to expand...
I'm pretty sure the current tune is good or at least as good as I can make it without changing more stuff or downloading some sniper software. I run the MSD distributor with black bushing and total timing on my engine is 32 degrees. With that black bushing (18 degree) I found 14 initial is the best spot for driveability, when I tried more initial like 16 and 18 it did not perform very well off the line. I could certainly try a different bushing like the larger bushing made by FBO (they make a 14 and 10 degree) that will allow more initial. Not sure if that will cool this thing down 40-50 degrees though? Anything will help and that would be pretty easy to do as well
 
If it cools down when driving, then you don't have enough air flow through the radiator to cool it down or tune problem.
Base timing low, running lean, low fan/wp speed?
If engine is at 240, your fan clutch should be locked to have fan pull air across rad, you say radiator has no hot spots, at that temp it should burn your fingertips when trying to lightly touch to feel for cool spots.
Engine is modified so cooling system also is needed.
Confirm coolant Temp. What is outside coolant temp are we talking about?
Add a pusher fan that turns on at idle/slow speed for a test?
 
I DO NOT CARE what your timing is mine does not overheat running even just 5 degrees and parading.

With the car stopped, the hood down, and the engine idling
There is only one thing you need to know which is this;
Can your rad bring the temp down about 30 degrees between the fluid coming in and the fluid leaving?
If it cannot, and the rad is of a reasonable size, just figure out the why of this and fix it.

My guess is that there is not enough airflow across/thru the fins.
Your choices, in no particular order, are;
1) go to a direct drive shrouded fan, and retest. Make sure only fresh cold air is being pulled into the rad.
2) add fan blades
3) drive the fan at a faster rpm
4) drive the pump faster, and/or add vanes and efficiency
5) make all the hot water go to the rad, ie, restrict the bypass.
6) make sure the hot air can exit the underhood
7) supply fresh cold air to the carb.
8) when all else fails, consider if the engine is creating more heat, than would be normal. Ie is the idle timing really that late, or are the ring gaps too tight, etc.


FYI
My rad is and has always been, a 1973 A/C rad off a 318 car. It is installed into the original 19" core support. I run a 195HV stat, the HV pump, a 7 qt oilpan, the Airgap intake, and a a big hole in my hood sealed to the airhorn. I installed a Direct drive 7-blade fan, and it still ran hot.
In my case, the heat was coming from too tight ring gaps. After I opened them up from a gap factor of .065 to .085, the engine ran much cooler so I heated it up.
First thing I did was to install a THERMOSTAICALLY controlled clutch on a 7 blade fan, which now controls the temp to 207*F, cycling in and out as may be required.
I haven't more than glanced at the factory temp gauge since about 2001. I run whatever timing I want at idle, from 5* to 20*, adjusting it from the front seat with my dash-mounted, dial-back, timing module that has a range of 15 degrees.
As far as I can tell retarded timing at idle that causes atomic meltdowns is greatly exaggerated. Get your Transfer port set right, and the Idle-AFR close, and in my case, the engine could care less about IDLE-timing.

Oh, I forgot, my engine is a hot lil 367. It has had three cams in it from 270 to 292 intake duration; and Cylinder pressure from about 180 to as much as 195 psi, and as for cooling and idle-timing, ran about the same with any of the cams, once the rings were loosened up..
It has gone 93 in the Eighth.
 
OP, this was answered correctly in post 9.

You need to over drive the water pump. And the fan. Low speed cooling issues are usually a water/air issue.

If CVF has a 20% over driven pulley set please post up the part number.

I’m at 6% over right now but I would gladly go 20 over.
 
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