Running hot with E fans

927 Views 7 Replies 6 Participants Last post by Grimbrand, May 15, 2022

68coupe5.0

Discussion Starter · May 13, 2022

Hey guys,
I initially had an aluminum rad with clutch fan and didn't have any temperature issues. About a year ago I ended up putting in a new radiator since I was installing A/C and threw in electric fans. Now the engine runs pretty warm and it takes a long time to cool back down. It gets up to about 220 where the fans kick on, then it takes about 15 minutes for the temp to drop to around 180. Sometimes if it's hot out (90F) the temp doesn't drop enough for the fans to shut off under normal driving conditions and they just stay on. The set up I have is:
Mildly built 302
T-5 trans
A/C
ACP copper/ brass rad maxcore 3 core (PN:FM-ER006 from cj pony parts)
Dual electric 12" fans 2800 CFM w/ shroud also from cj pony parts with matching controller
180 deg thermostat

I've messed around with sensor placement, sealed up all the gaps between the radiator and shroud, replaced the thermostat, and burped it a number of times. No indications of a blown head gasket. I've thought about getting a fan controller that is variable, but I'm concerned that the temp takes so long to come back down. My next thought is to replace the radiator with an aluminum one but I wanted to see if anyone had a better idea before I start throwing money at problems. Any input is appreciated.
Thanks

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Grimbrand

· #2 · May 13, 2022

Aluminum radiators don't typically cool any better than the copper/brass ones - they're just a little lighter. And they get corroded faster, because the aluminum tries to "fix" rust in the block, as a sacrificial anode.

My take on this? Get a good shroud and run a thermal clutch fan! They work great.

But I should also add - 220 isn't insanely hot. Even with a 192 thermostat - which you should probably be running - it shouldn't get any hotter than it does now. It'll just prevent sludge buildup when it's cold.

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crjackson

· #3 · May 13, 2022

Does it cool down with a good amount of uninterrupted highway driving? I’m curious to find out if the constant airflow cools it any better.

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07redstang

· #4 · May 13, 2022

You need to set your fan temp switch to turn them on earlier. Aluminum radiators are lighter and more efficient than copper/brass.

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GypsyR

· #5 · May 13, 2022

If you Google "optimal operating temperature for a gasoline engine" you get "between 195 degrees and 220 degrees". So it's not broken, stop fixing it. If you don't want to run quite up against 220 set your fans to come on a tad earlier.
Though I would suggest tossing that 180 degree thermostat for a more factory correct 192-195 one. That would help you get your engine closer to the optimal operating temperature where you find your best power and fuel efficiency. I like more power AND better gas mileage myself.

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Tony 64

· #6 · May 13, 2022

That is a normal temp range for these motors.
Staying hot after shutdown is also normal.
One thing nobody has mentioned yet, Are the fans working in the right direction? Are they pushing air into the radiator or towards the engine?

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68coupe5.0

Discussion Starter · #7 · May 14, 2022

Agreed the engine temperature itself isn't concerning. The problem I've been running into is that the fan controller is fixed and is suppose to turn on at 200 and off at 180, but on warm days it doesn't drop back down to 180 so the fans stay on constantly. I've been running a 180 thermostat for a few years and haven't had any issues, until now, but maybe I'll switch over to a 192-195 one in the future.

The fans are blowing toward the engine, so pulling air through the radiator.

Even on highways the engine will creep up in temp, just slower than in city traffic. Which I didn't expect to happen, with the mechanical fan it would find a steady temp and maintain it.

I've replaced that sensor since the fans don't switch on until about 220 and it didn't seem to help. I think you're all right and the temps that the fans are coming on/ off are the issue, not the actual engine temp, I'll snag a variable fan controller so I can adjust them, let you know how it goes.

Thanks!

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Grimbrand

· #8 · May 15, 2022

I'm going to bet that this is a CFM issue with the fans, or perhaps no plenum/shroud so that it's only getting cooled through a couple of circles where the fans suck from.

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