Hey guys. Hopefully someone might have an idea. I have a 69 stock 440 that over heats if she comes to a stop for any length of time, however she could drive across the country as long as she never had to stop. Things that have been checked,replaced, or installed are: 1. Checked the water pump housing for any restriction, 2. replaced the water pump, 3. a variety of thermostats have been installed even one that had the guts removed so it was just a pass through. 4. a variety of fans, from fixed fans to flex fans, all while having a correct fitting shroud in place, 5. replaced the radiator from a stock, to a 4 core, to now currently an aluminum 4 core. 6. it is timed correctly 7. now have removed the fan and have installed electric fans in a push and pull (correct fitting custom shroud on the pull fan) the pull fan was installed first, still not enough so the push fans were installed. 8. pulleys have been replaced with a march pulley system. 9. have removed the insulation pad from the inside of the hood. Any new ideas would be greatly appreciated! Thanks in advance. I am working doubles over the next couple of days, so if you ask a question and I don't get right back, its not a slight, I'm simply at work with no computer access.

How hot? & how hot at the stoplight and how hot on the road. confirm with a known good reading gauge. what came to mind is block cooling passages full of crud and a possible combustion leak into the cooling system. tho I would think either of them would make it run hot or at least significantly hotter at speed. On those two if it is one of them: A person can pull the core plugs & blast it out with the car wash wand/an emmissions testing station can set their probe in the air space above the coolant in the radiator & it'll immediately show the presence of hydrocarbons. this is a toughie! keep us posted. At first blush it sure sounds like inadequate air & possibly water flow at slower speeds. is the fan properly positioned into the schroud?

Your symptoms indicate inadequate air flow at low speed, You're dual electric fans maybe be contributing.

More info is needed, IE: Radiator size and source, Fan sizing and source. To properly diagnose:

Step one: verify actual temps with a thermocouple and quality meter.

Step two, report your findings

All of ur fixes have been external to the engine...
Sounds like ur internal water passages are plugged, and the block/heads needs to be flushed out..

Just my $0.02...

When you have combustion leakage into the water you will know it. It will blow the radiator cap, maybe, clean off. But you'll know it. With the cap off and radiator full, when fired up, you will have a geyser or a huge amount of water and "air" coming out. Its pretty exciting actually.

I gotta agree with SportF, if it was leaking a slight bit of combustion at idle it for sure would get worse "at speed" & it ain't cuz it is OK "at speed". K.I.S.S. start with how much air is flowing across the rad fins at idle. EDIT what is your pulley ratio?

Maybe you've done this already, but didn't talk about it. You really need to have a known laser temperature reader at the ready to know exactly what the temps are at the thermostat -- I wouldn't trust the temp gauge on the dash - ever.

What are the symptoms when you are "overheating"? Talk about that as well as the procedure that you know what the over heat temps are. I'm assuming you have a 26" radiator in your car, is this correct? You should also let us know, what water pump did you replace in your engine? Did you replace with a FlowKooler in there or is it a stock water pump? Also, with the fans, there are a million of them out there -- what exactly are you using, and what control are you using to make them turn on?

This will get you started:

https://board.moparts.org/ubbthreads/ubbt...tml#Post1463496

Temp guns are good for telling you temps.

Pure Water: 0 C / 32 F - 100 C / 212 F
50/50 mix of C2H6O2/Water: -37 C / -35 F - 106 C / 223 F


@ 15 psi raises the boiling point another 45 F (25 C)
50/50 + 15 psi rad cap = 131 C / 268 F

Make sure you have a maximum of a 50/50 mix (being in NY, 60/40 would be better).
Pure water transfers heat a lot more effectively than C2H6O2.
Good airflow through the rad ( a loose leaf paper that stick to the rad
with the fan on is a good indication)
Good rad cap of at least 15 psi.

^^ those are the basics, now;

Check to see if the water pump pulley is glazed. Belt could slip on it.
Oversize W/P pulley? Right diameter pulley?

You have really been over that cooling system! Agree it is important to know how hot at a standstill. I would be fine with 210 and OK with 220 as long as she cools down on a roll. Over that, not so much.

One thing to contribute to the list of ideas. What is the pulley ratio? Crank pulley diameter divided by fan pulley. These seem to cool best with the fan and waterpump overdriven at least a little (crank pulley bigger than fan pulley). The factory "with AC" setup had quite a bit of overdrive. Mine runs about 1.07 ratio with a high volume water pump and 6 blade thermal clutch fan + shroud.