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 overheating 400
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jrhinke
Tribal Scout

USA
1 Posts

Posted - 14 Aug 2009 :  2:25:49 PM  Show Profile  Reply with Quote
Osbournes pro street rebuilt a 400 for me 5 years ago. I have less that 1000 miles on the rebuild due to overheating problems. I've tried everything. Upgraded to Meizre electric pump this spring, runs 20 degrees cooler at highway speed, but soars at idle. Had several different thermostats in it, big AL radiator, 2 electric fans. Today brought it home from the shop 90 degrees outside. Car ran on country roads at 200 degrees. Ready to light it on fire. 10.5:1 CR, 6x heads, big cam (no idea on lift/duration). Any ideas??

Joe

Vid
Kicking Horse

USA
1685 Posts

Posted - 26 Aug 2009 :  07:36:41 AM  Show Profile  Reply with Quote
But 200 degrees is right where you want it. 180-210 range is normal warmed up operating temperature. Just how hot is it getting? No need to get nervous until it hits 230+

Have you checked the water pump? Could be it was assembled without the metal plate that covers the impeller.
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Bill Boyle
Horse Feathers (Charter Member)

USA
4794 Posts

Posted - 26 Aug 2009 :  08:01:33 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Vid is on the money with the typical running temperature of Pontiac engines on the street.

With only the stock gauges in my TA, I used to go crazy watching the temperature needle climb as I sat in traffic with the AC running. It made me nervous. Finally, I decided to add a second temperature gauge to the engine and low and behold discovered the engine was not running the temperature indicated on the stock gauge. It cut my anxiety to nothing.

I continually answer questions on temperature by knowing if the thermostat in the engine is a 160 and if the darn thing really opens fully at that stated temperature. Test and retest thermostats until you find one that really is operating correctly. The second point is knowing if your gauge is accurate or not.



"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.

Edited by - Bill Boyle on 26 Aug 2009 08:02:17 AM
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rad400
War Paint

USA
1251 Posts

Posted - 26 Aug 2009 :  08:37:10 AM  Show Profile  Reply with Quote
you need a 6.5" water pump pulley and a 8" crank pulley. Measure what u have and go from there.

Conrad
79 Trans Am 400 auto Crower 60210 Torker II Holley 750 vac sec. #12 heads,3500 stall.
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Taman
Red Bird

USA
844 Posts

Posted - 01 Sep 2009 :  10:25:16 PM  Show Profile  Reply with Quote
Do you run hoses from the back of the heads to the water pump. If so, take the heater hose return line off the water pump and plumb into the manifold. My Torker 2 has 2 places to run the temp sensor. I moved the temp sensor from the pass. side to the drivers side. I ran one line per head and fed into a T into the manifold where the temp sensor was. Now the hot return water from the head is not mixing with the cool radiator return coolant. The hot head coolant returns back to the radiator. Also, the front bypass to the intake manifold coolant passage can also be blocked for the same reason. If you do these mods I would drill holes into the thermostat as not to dead head the water pump. I run a Moroso restricter washer instead of a thermostat. My TA runs 180 in stop and go traffic in ANY temperature. I make 562 hp in a 400 based 461.

Everything Under The Sun Is Intune
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cortcomp
Coyote

USA
5335 Posts

Posted - 07 Sep 2010 :  1:38:37 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
quote:
Originally posted by rad400

you need a 6.5" water pump pulley and a 8" crank pulley. Measure what u have and go from there.



Didn't he say electric water pump?

If not, do run the bigger crank pulley with the smaller water pump pulley, helps with more flow at idle.

Also, mine ran at 165 and i put a 195 stat in to get it warmed up a bit more. Runs at 200 to just under 210 at any speed, A/C, etc. The warmer temp seemed to improve it's manners a little, i'll see after a few tanks if it helps MPG.
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mike mcarthur
Pony that Jumps

USA
2475 Posts

Posted - 07 Sep 2010 :  5:37:18 PM  Show Profile  Visit mike mcarthur's Homepage  Reply with Quote
I've never had an overheating problem with any Pontiac. The GTO runs about 190-200, the wagon doesn't have a gauge, but has been together for 20 years and close to 200K miles, and the GP runs about 200-210. When you say it soars at idle, what are we talking about?

It's the stuff you learn after you know it all that's important
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