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Operating Temp? What is normal or acceptable? HELP

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Old Jun 3, 2003 | 11:57 AM
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Default Operating Temp? What is normal or acceptable? HELP

My 1978 Corvette which I recently bought was running at about 205 normally. I changed the radiator to a two core Modine and the Thermostat to a 160. I put in a new water pump and my temp now goes beyond 220. HELP!

The temp will only rise when I am driving it around. Not on idle. Most have told me that the water pump seems to be the problem even though it is new. I am now changing it to a Carter.

My question is, what is normal operating temp for a 1978 in Hot Miami, FL?
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Old Jun 3, 2003 | 12:07 PM
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Default Re: Operating Temp? What is normal or acceptable? HELP (Miamivette)

Make SURE you dont have an air pocket in the system someplace. Either take the stat out or drill a couple of small holes in it, run the motor for a while with the rad cap off, look for any air bubbles rising to cap. after that top off rad again, reinsert stat or a new one w/o holes. Try that. It worked for me.....GOOD LUCK! :cheers:
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Old Jun 3, 2003 | 12:09 PM
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Default Re: Operating Temp? What is normal or acceptable? HELP (Miamivette)

Did you change to lower hose? If so did you get one that has the anti-collapse spring in it or transfer your old spring to the new hose? Under higher rpm's the lower hose will collapse without the spring reducing flow.

To check for air pocket get a pair of gloves and squeeze the upper hose when fully warm, if air is in there it will collapse rather easy, if not it will be very firm.


[Modified by Fevre, 11:12 AM 6/3/2003]
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Old Jun 3, 2003 | 02:46 PM
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Default Re: Operating Temp? What is normal or acceptable? HELP (Miamivette)

I'm just accross the state from you .. hot here too. :mad My car used to run at 220 all the time. I replaced the rad cap and it dropped to about 210, but got hotter on the highway at higher rpm, usually 230-240. I was told that was normal.
My water pump started making noises, so i replaced it with a Stewart High Flow pump. Now the temps stays down around 170. On the highway it will get up to 210 if I run at 3500+ RPM in 90+degree weather, but that's as high as it will go.
Oh, I also recently replaced the fan clutch. When I come to lights, if the temps climbs to say 190, the fan clutch engages and cools it right down.
Unfortunatley, at 3500+RPM on the highway with the A/C cranked down, the fan clutch can only do so much. But from what I've read, in that situation, 210 is good.


[Modified by isosceles, 1:46 PM 6/3/2003]


[Modified by isosceles, 1:47 PM 6/3/2003]
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Old Jun 3, 2003 | 02:50 PM
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Default Re: Operating Temp? What is normal or acceptable? HELP (Miamivette)

Hi temps scare me. The lower does have its spring and the top hose is always firm. Thank you.
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Old Jun 3, 2003 | 02:59 PM
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Default Re: Operating Temp? What is normal or acceptable? HELP (Miamivette)

Do you have the bottom, for lack of a better word, spoiler installed? This is what directs the air up through the rad at highway speeds.

If my gauge is to be belived, I never get above 200-205 under any conditions. I have a 4 core rad, 180* thermosta, and original water pump.
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Old Jun 3, 2003 | 04:17 PM
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Default Re: Operating Temp? What is normal or acceptable? HELP (glen242)

You also can't trust the gauges, I know for a fact mine is 15 degrees high. My gauge runs a consistant 200, yet my true temp is 185.

You may want to check that out prior to investing more time / money.


[Modified by 75Rag, 9:18 PM 6/3/2003]
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Old Jun 3, 2003 | 04:31 PM
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Default Re: Operating Temp? What is normal or acceptable? HELP (75Rag)

i only have one temp sensor hooked up, and I read at about 230 degrees, but the true temp is about 195
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Old Jun 3, 2003 | 04:35 PM
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Default Re: Operating Temp? What is normal or acceptable? HELP (Miamivette)

I changed the radiator to a two core Modine and the Thermostat to a 160.
I just re read this. I'm no pro but .. In FLA is a two core enough? I'm up here where it is substantially cooler and when my 3 core finally crapped out I put in a 4 core ...

Maybe you just don't have enough capacity ..... :confused:
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