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Old 08-25-2018, 10:45 PM   #1
Steven67c10
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Join Date: Jul 2018
Location: Spring, TX
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Over heating problem

Hey guys, so I just bought a 69 c10. Truck has a 350 with aluminum heads and cam. Truck has a/c as well. Well when cruising down the highway at about 65 it’s at 3200-3300 rpm. It starts to go up pretty quick. When I noticed it going to 220 I slowed down and pulled off the highway. I’ve noticed it only does it when I’m on the highway and staying at or above the 3k rpm range. At idle and just cruising around town it stays at 170-180 all the time.

Any help on what I need to do to fix this problem. It has dual fans but maybe I need a bigger radiator. Maybe a new thermostat sensor?

Thanks guys
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Old 08-25-2018, 11:53 PM   #2
Steeveedee
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Re: Over heating problem

#1 cause for running hot at high speeds is a bad radiator. Getting it cleaned or replacing it should cure the problem.
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Old 08-25-2018, 11:58 PM   #3
Boog
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Re: Over heating problem

Reducing the rpms will lower the engine heat as well. Either slow down or swap the rear end gears to a higher ratio will lower the engine heat. Or if ya got bucks, installing an over drive trans or gear vendors od unit will get ya there.
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Old 08-26-2018, 12:21 AM   #4
Jcfcamaro
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Re: Over heating problem

I'd say it's the radiator also. Buy a new aluminum one as it will cool alot better. ECP makes a real nice one. That's Engineering cooling products. Put one in my Camaro and all my problems went away.
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Old 08-26-2018, 01:30 PM   #5
68 P.O.S.
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Re: Over heating problem

Do you have a shroud?
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Old 08-26-2018, 01:44 PM   #6
Jcfcamaro
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Re: Over heating problem

Yes, My original radiator was taken to a shop and was redone. Had a shroud on it also, but would run hot. Everyone said to ditch the solid 4 blade fan and get a clutch fan so I did with no response.Even played around with different thermostats. Ended up buying the ECP radiator and all my problems went away. When I get closer to getting my 72 k10 with A/C I'm buying one for it. I have a factory radiator for it, but it would need sent to the shop to be tested/fixed and I'm not going down that path again and waste money.
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