Running hot

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Running hot

Postby Astre-mutt » Thu Jan 10, 2008 7:00 pm

Is there an inherent problem with air flow through the radiator on 76 Pontiac Astre's? I purchase my car with a 4.3L chevy V6, TH350 trans, a full size 4 core radiator with electric fan. The car would run at 190 degrees down the road. When it would hit 200 at a stop the fan would come on, and the temp would drop quickly below 190. I went to a 160 degree thermostat. But it made no difference. So I figured the radiator wasn't getting anuf air flow. So I put a front air dam on it. Now the car runs 160 degrees. But the recovery is still a little slow after a stop. My next step will be to sheet metal the gap between the lower valance and the lower radiator support. I think this will solve the problem. But I haven't read about any one else having this problem on this on this site, and I'm afraid that I just put a band aid on a some other problem.
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Postby Sirshredalot » Thu Jan 10, 2008 8:25 pm

Coolant system pressure can play a role too.

Try a 16lb or 20lb radiator cap and make sure you have a functional recovery/overflow tank.
The air dam will help as will sealing up all the cracks to force as much air through the radiator as you can.

Make sure the shroud seals to the core support too.

The slow recovery can be typical....the engine bay is very tight and small therefore hard to start heat disipation after airflow starts again... especially
with headers and high performance engine mods.

God bless
-Shred
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Postby spyder_xlch » Thu Jan 10, 2008 8:49 pm

Going down the road at about 40-45 and higher is one thing. You have plenty of air flow. Putting an airdam on a car that didn't have one will help. At a stop or at slow speeds is another thing. Is the fan a pusher or puller? Do you have a shroud?
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Postby Astre-mutt » Thu Jan 10, 2008 9:47 pm

I'll check the radiator cap pressure. It has a new overflow tank. The fan is set up as a puller, and is one of those cheap electrics that attach to the core. The person I bot the car from kept it in great shape. But to say they where a shade tree mechanic would be an under statement. I'm still sorting the car out. As far as air flow at speed, the fan pulls more air then driving. I should also mention the car has low gears. I don't know what they are yet, but I would be shock if it could hit 100mph with the stock 13" wheels. (lots of fun stoplight to stoplight) I have taller tires. I'm waiting on the adaptors.
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Postby spyder_xlch » Thu Jan 10, 2008 9:52 pm

Are you saying the fan pulls more air sitting still than what flows through on it's own at speed? If so then maybe the water pump isn't pumping enough at low RPM or you have a blockage somewhere.
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Postby Astre-mutt » Thu Jan 10, 2008 10:40 pm

Don't think there is any real cooling system problems. It stays at 160 to 170 degrees now. I'm just surprise I'm having any problems at all. (Stock V6 with big radiator) The car sits on the low side, and it seamed to me by just looking at it air was being trapped by the cross member. (that's why the air damn) Yet I see so many people running high horsepower V8s, and no modifications to air flow to the radiator. (ductwork, air dams, etc.) But just to be safe, and to save weight I plane to redo the entire system with aluminum. (water pump - radiator - fan shroud)
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Postby HI WINDING MONZA » Thu Jan 10, 2008 10:49 pm

The aluminum radiator should help you alot since it doesn't hold heat like brass-copper. Give it a try . Doug in AZ
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Postby Astre-mutt » Fri Jan 11, 2008 5:16 pm

Great call on radiator cap. Checked it out today. It's a 7 Lb. cap. I'll get a 16 Lb. cap. I think this will help my recovering time.
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Sirshredalot calls it right again

Postby chevyart » Sat Jan 12, 2008 12:45 am

great call on that overheating problem. You must be wired directly to an automotive repair and troubleshooting computeror you are an automotive genius.Sirshredalot for president...Sirshredalot; punch into your computer search scotty anderson, guitarist. there are many places to go to and once you see one you will need to see and hear them all. finest guitarist on the planet, and guess what he is a fingerstylist. look for a site with scotty and bob saxton. he aa real old guy that played with scotty at a ohio fingerstyle get together. I just cant imagine anyone or i should say any two guys being this good. Maybe , just maybe Eric Clapton could be their roadie. I have a DVD of that show and two real good instructional dvd on fingerstyle instruction to teach you the chet atkins style> if there is a way i can transmit them on the computer i will or ill send them to you and you can copy them and send them back. also try you tube to see scotty and bob. Keep up the good work Chevy Art. PS I used to be Ford Art in the early 60s but I got smart and changed over. If I didnt I would probably be talking on a mustang or Pinto site right now..
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