Overheating problem! Help!

[joew94th]

The fan is pulling air towards the engine, correct?

Yes! It's a puller. May not be pulling enough, but I would think that at speed it wouldn't matter. The natural airflow through the system would cool it even without a fan at all.

 

[joew94th]

These guys are correct....that electric fan has to go. I recommend a factory (non-flex fan) stock style fan with fan clutch. Search around for "some type" of a factory fan shroud, modify the hell out of it if necessary so it fits & the fan blades are 1/2 way inside the shroud and your cooling problems will be gone. Also, Just in case you have a big air bubble in your cooling system, a small 3/16" hole drilled in the thermostat or a fail safe type thermostat will let air bubbles out.

Also, Just in case you have a big air bubble in your cooling system, a small 3/16" hole drilled in the thermostat or a fail safe type thermostat will let air bubbles out.

The hole in the thermostat thing is a new one to me. This is to let trapped air from the engine to get into the radiator when the thermostat is closed? Correct? If that's the case, I'm not sure it would help as I verified the thermostat was open before I drove around the neighborhood. That is to say that I could see the coolant moving from the radiator cap once the thermostat opened.

 

[joew94th]

So it sounds like I should...
1. Make sure there no remaining air in the system. I've got plenty of good hills around here. I'll get it warmed up and park on a hill facing uphill. maybe do this a couple of times.
2. Get rid of the electric fan, go back to factory fan. I don't have a clutch on the factory fan. Do they make a big difference?
3. If I run into problem with stop & go traffic, I'll look to putting a shroud on it. The only shroud Summit sells for this radiator had too small of an opening for the factory fan. I'll have to make one I guess. I'd rather not, but it's not impossible.
4. If all of that still doesn't work I'll have the old radiator re-cored and put it in. Everything I've read says the aluminum radiators are better at cooling because the opening in the fins are larger. Pound for pound aluminum is stronger than copper therefore they can cool with fewer rows of fins. The reason they didn't use aluminum back when these cars were built has to do with cost. Aluminum was way expensive in the 1960s.

 

[WileERobby]

Well, no! Not quite. I replaced a system that wasn't working for one that I was told should work. I might put the factory blade back on though.

YOUR words: "I have never had a cooling problem until then. Even on hot days, the 360ci in my '66 Belvedere rarely went above 190 degrees." You had a system that functioned perfectly. And you changed it to something different. Yes, there was a malfunction. Correct the malfunction, but you decided to change the system. Recore the radiator. And you have the same functional system that worked fine.

 

[joew94th]

YOUR words: "I have never had a cooling problem until then. Even on hot days, the 360ci in my '66 Belvedere rarely went above 190 degrees." You had a system that functioned perfectly. And you changed it to something different. Yes, there was a malfunction. Correct the malfunction, but you decided to change the system. Recore the radiator. And you have the same functional system that worked fine.

You may be right, but I think I'll try a few other tricks first. I see an awful lot of aluminum radiators out there that seem to be working just fine.

 

[Ron H]

Some love and hate with electric fans and they work and not so much. When I had overheating hassles after motor rebuild, removing some iron from the block, found that some aftermarket shrouds can take one from bad to worse as the air turbulence cools everything but the motor. Then there’s the critical distance with the fan to radiator. With my car found out that a shroud was only provided on police and A/C rides. Found an OEM shroud I restored and installed. My car had a 4-blade fan and installed a 7-blade. Another option was a top of radiator seal my ride didn’t have and put that in. Nice add as the bug juice splattered under the hood ended. Doing more reading came across coolant mix or ratio articles. More coolant can retain more heat. I reduced the common 50/50 to around 30/70 since I don’t drive in the winter and it sits in a heated garage. Added a product called water-wetter; some have said there’s other less expensive stuff that does the same thing. Another thing I determined is the motor oil viscosity I was using was unnecessary for my engine and had noted some way high oil pressure anyway. So changed this. Too much? I obtained the desired results, as had been thinking of another radiator or even an electric fan I found I didn’t need.

 

[Don Frelier]

The fans on my charger never run going down the road. It has a cheap eBay 22" aluminum radiator.

 

[Dennis H]

Shroud. Aluminum is over rated.

 

[joew94th]

We built this one with the Summit cross flow.451 big block using the factory clutch fan, no shroud. Worked fine.
I have had both big and small block engines that took some time to "Burp" the system even with the drilling of the thermostat. Just saying it's possible. Are the hoses new ? Lower hose have a spring to keep it from collapsing ?

View attachment 1544162

I think you hit the nail on the head with the "burp". I thought I had all the air out, but I was wrong. I raised and lowered the front of the car while running. It burped again and lowered radiator level 1.5" I topped it off and drove it again twice as far. Still running hot at 230 but didn't over heat. I've probably got some more air in there somewhere.

 

[joew94th]

Sounds to me like you still have air in the system. If your cross flow radiator is mounted with the pressure cap higher than the engine, the radiator is self bleeding. However, if the radiator is placed lower than the engine, a surge tank or bleed line is required.

Yep! That was it. This thing was stubborn. Each time I drove it it would burp a little bit more. Finally got to the point where temp stayed around 190.

 

[joew94th]

About 3 weeks ago my OEM radiator sprung a leak. I have never had a cooling problem until then. Even on hot days, the 360ci in my '66 Belvedere rarely went above 190 degrees. I decided to replace the radiator with a brand new universal fit aluminum cross-flow radiator from Summit. I also replaced the flex fan with an electric one. I installed new hoses and a 160 degree thermostat, 50/50 mix of antifreeze & water. Everything is fine at idol, about 190 degrees after 10 minutes. The thermostat seems to open at the right time and I can see the coolant flow, so water pump is working. One trip around the neighborhood and the temp goes up to 250 degrees and radiator boils over. This radiator is about the same dimensions as the old OEM copper radiator. I've read that cross-flows are supposed to be more efficient. The one difference is that I no longer have a shroud. It's hard to imagine a shroud would have that much difference.
Any help is appreciated!

View attachment 1543973

Problem solved! It wasn't the fan, or the aluminum radiator. It was just stubborn air in the system. Took forever to get it out. I finally lifted the radiator out of its cradle as far as I could and got the last bit of air out of it. Thanks for all the suggestions!

 

[Rebelrouser]

About 3 weeks ago my OEM radiator sprung a leak. I have never had a cooling problem until then. Even on hot days, the 360ci in my '66 Belvedere rarely went above 190 degrees. I decided to replace the radiator with a brand new universal fit aluminum cross-flow radiator from Summit. I also replaced the flex fan with an electric one. I installed new hoses and a 160 degree thermostat, 50/50 mix of antifreeze & water. Everything is fine at idol, about 190 degrees after 10 minutes. The thermostat seems to open at the right time and I can see the coolant flow, so water pump is working. One trip around the neighborhood and the temp goes up to 250 degrees and radiator boils over. This radiator is about the same dimensions as the old OEM copper radiator. I've read that cross-flows are supposed to be more efficient. The one difference is that I no longer have a shroud. It's hard to imagine a shroud would have that much difference.
Any help is appreciated!

View attachment 1543973

I struggled with a engine getting hot a few months ago, mild 512 in a 4x4 dodge truck that originally had a 400 big block in it. I am a retired technician and former automotive instructor. After a lot of work, I figured out the root cause was lack of coolant flow, the two big culprits were an aftermarket radiator and the wrong diameter water pump pulley on a serpentine belt conversion. A two core aluminum radiator compared to a 4 core aluminum radiator, of the same size, the two core flowed more and cooled the engine much better. A smaller diameter pump pulley increased coolant flow and was the major part of the problem. I tried mechanical and electric fans shrouds etc, and while they helped it is only a small part of the system. I even went with a higher volume aftermarket water pump. So be sure the radiator you purchased will flow enough.

 

[PurpleBeeper]

The hole in the thermostat thing is a new one to me. This is to let trapped air from the engine to get into the radiator when the thermostat is closed? Correct? If that's the case, I'm not sure it would help as I verified the thermostat was open before I drove around the neighborhood. That is to say that I could see the coolant moving from the radiator cap once the thermostat opened.

Correct….let’s air bubbles out if they’re there

 

[Bird 426]

Go back to what worked, and sell all of that cool stuff you bought that actually isn't so cool. Ask me how I know this.
We all make mistakes, it's knowing how we deal with them that makes the difference.

 

[Struttmaster]

I’d put the old thermostat back in and see what happens.

 

[dadsbee]

You may be right, but I think I'll try a few other tricks first. I see an awful lot of aluminum radiators out there that seem to be working just fine.

No.. you see a lot of aluminum radiators in pictures. Many come here to advise us they're running hot! What you had worked, go back to it! Refurbish the old copper radiator and be happy again!

 

[RJRENTON]

Correct….let’s air bubbles out if they’re there

Once the t-stat opens for the first time, any entrapped air will be relieved. Most replacement t-stats have sn air bleed incorporated.....
BOB RENTON

 

[Some Car Guy]

Shrouds and fans matter at idle and low speeds. Once at road speed of about 35 you don’t really need a fan. Air flow takes over. Overheating going down the road is a problem of too small capacity or flow issue.

I used to think shrouds were a big deal because people constantly talked about them, until I had a car with a broken one when I got it. It ended up falling on apart and I took it off until I could get a new one…except I noticed zero difference on the mechanical gauge. So now I look elsewhere for cooling issues.

 

[Darter6]

at road speed of about 35 you don’t really need a fan.

Drove a slant 6 across the country with no fan 2500 miles of interstate just because I wanted to see what would happen.
Now that was in January with temps anywhere from 60+ to about 20*. Even had to put card board in front of the rad to get the heater comfortable. It did have a 160* thermostat.