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Okay guys.. I know this question has been asked several times and I know I have asked before.. But I'm still having some overheating problems..

A bit of background.. I have a 62 with a 383 and TPI, 350 turbo.. I installed the Summit aluminum radiator SUM-380325 with a 16 inch elec fan. I put a new heavy duty Duralast CWP-520HD water pump (HD PUMP UTILIZES ROLLER BEARINGS, CERAMIC SEAL AND REDESIGNED IMPELLER WHICH DELIVERS INCREASED COOLANT OUTPUT.) 180 degree thermostat, new hoses, new 16 lbs cap, etc.. Running pre mixed antifreeze...

Running around town on a 80 degree day it runs about 200 degrees is what the ECM is telling me my temp gauge is in the left head and it says about 210. I can sit and idle all day long and never gets above 200.. I get up on the hwy and the temp jumps up to 230.. On a 90 degree day on the hwy it will jump up to 245 at the ECM and 250 on the gauge.. if I turn on the A/C oh my god.. 260 plus..

Any suggestions..

Mitch
 

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taking into consideration

What you have said leads me to believe the coolant is flowing faster than the radiator can cool it, in other words it just doesn't spend long enough in the radiator to dissapate the heat. If you want to try an easy solution for this, try using a Moroso part # 63440 coolant restrictor kit. Use the smallest of the three, the middle one is the same as an open thermostat and the larger would allow more coolant flow.

I had this happen on another of my cars and wound up removing the high flow pump and using the restictor. It's definitely a cheap way to see if that is the problem, I think they are only around ten bucks.

David
 

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What's your timing at? Does the vacuum advance work? Carb adjusted right? Is there a wire spring in the lower hose to keep the hose from collapsing? Your fan set-up should have nothing to do with the highway cooling unless it is restricting air flow. Did you check the performance of the thermostat before (or since) to see that is is opening enough? You can put it in a container of water and heat up the water with a barbeque or a stove. Drill two or three 3/16" holes outboard of the opening. This lets addition coolant through. There are high flow thermostats that can be used.
 

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NOTANOVA said:
What you have said leads me to believe the coolant is flowing faster than the radiator can cool it, in other words it just doesn't spend long enough in the radiator to dissapate the heat.
The coolant needs no specific 'time' in the radiator to cool, the laws of physics dictate that the hotter you can make the radiator, the more heat it transfers. This would be accomplished by moving as much hot water through the radiator as possible. I would come to just the opposite conclusion here, that there is insufficient water flow through the radiator which reduces the cooling system efficiency. To quote Stewart Components:

A common misconception is that if coolant flows too quickly through the system, that it will not have time to cool properly. However the cooling system is a closed loop, so if you are keeping the coolant in the radiator longer to allow it to cool, you are also allowing it to stay in the engine longer, which increases coolant temperatures. Coolant in the engine will actually boil away from critical heat areas within the cooling system if not forced through the cooling system at a sufficiently high velocity. This situation is a common cause of so-called "hot spots", which can lead to failures.

Here's some good info on automotive cooling systems:

http://www.stewartcomponents.com/tech_tips/Tech_Tips_6.htm
http://www.stewartcomponents.com/Tech_Tips.htm
http://www.arrowheadradiator.com/14...apability_in_high-performance_automobiles.htm

For some more physics stuff on nucleate boiling, etc:
http://www.tpub.com/content/doe/h1012v2/css/h1012v2_62.htm
http://www.tpub.com/content/doe/h1012v2/css/h1012v2_63.htm
http://www.tpub.com/content/doe/h1012v2/css/h1012v2_64.htm
http://www.tpub.com/content/doe/h1012v2/css/h1012v2_65.htm
 

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Laws of physics aside

I can tell you that slowing the flow of water through my cooling system significantly reduced the operating temp of my motor at highway speeds. 40 + degrees to be exact. I was wondering how the guy came to the conclusion that a cooling system was closed loop????? Considering there is a vent tube on the radiator cap to expel expanded, heated liquids. I guess technically it is closed loop as it should reabsorb the expelled liquids, but what if there is no puke tank?????

Seems to me he is saying that if I spend an equal amount of time outside at 95 degrees, versus an equal amount of time inside at 70 degrees I should not get hot. Seems to me the longer I stayed in the 70 degree climate the cooler I would stay.
Also, if the hotter you make the radiator the more heat it transfers were true, wouldn't the drag racers during cool down when they run the water pump with the motor off be putting torches to the fins rather than cold water?

So, believe what you want, I'm just telling what worked for me. And if you don't think that the amount of time coolant spends in a radiator has any effect on cooling, call Be Cool or Griffin. They are the ones that pointed me in the direction of slowing down coolant flow.

Of course, I am assuming you have checked all the points that Shane65 brought up. Tuning, hose integrity...etc. One other thing you may check that is often overlooked is the radiator cap. I had one go bad on a car and it wouldn't hold enough pressure and that caused a pretty bad heating problem as well. I know you said the cap was new, but check it anyway.

David
 

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However I di look at thhose links,

I did notice one thing, it did say that all of the info he was giving out was for cross flow radiators, and on the early novas (62-67) they were not equipped with cross flow systems. The tanks are on the top and bottom. Maybe that is why it worked for me.

Also from reading those links I would say that it was a possibility that there was enough flow to cause cavitation or bubbling, so maybe that is why slowing down the flow worked for me. What ever the reason slowing the flow, made mine run cooler at highway speeds. It was on my 67 nova ss, since I forgot to say earlier.
David
 

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I was wondering how the guy came to the conclusion that a cooling system was closed loop?????

Are you kidding me? It's a closed loop system because the coolant is recirculated continually in a closed loop. The puke tank has little or nothing to do with the cooling, it's basically an expansion tank.

but what if there is no puke tank?????

Then you will have a cooling system like the ones that came on the pre-1970's cars, just an overflow hose blowing the excess out on the ground. At some point there is sufficient air space in the radiator to allow for the expansion of the coolant without overflowing. Ethylene glycol isn't something you want to be blowing out on the ground if you can help it.

Seems to me he is saying that if I spend an equal amount of time outside at 95 degrees, versus an equal amount of time inside at 70 degrees I should not get hot. Seems to me the longer I stayed in the 70 degree climate the cooler I would stay.

Remember, for every amount of time you're inside cooling off at 70°, somebody else is roasting outside at 95°. You can't both be inside at the same time, and you have to stay outside longer also.

Let's say that your cooling system volume is equally divided between the radiator and the block, so that half the water is in the block heating up while the other half is in the radiator getting cool. Let's say that you have 4 gallons of coolant in the system and your water pump is pumping 20 gallons a minute. Using grade-school math we can surmise that the coolant will make a complete cycle through the system every 12 seconds, so that every minute the water spends 30 seconds in the radiator and 30 seconds in the block. If I double the flow to 40 gpm the water makes a loop every 6 seconds and still spends 30 seconds of every minute in the radiator and 30 seconds in the block. As you can see, the average amount of time the water spends in the radiator is the same no matter what the flow.

Also, if the hotter you make the radiator the more heat it transfers were true, wouldn't the drag racers during cool down when they run the water pump with the motor off be putting torches to the fins rather than cold water?

Let's get back on track here...you heat the radiator with the coolant, and cool it with air. Spraying cool water on the radiator works well because the specific heat of water is far greater than that of air.

Next time you're at the races, do an experiment. Get the engine uniformly hot, say 200° then shut it off. The first time you do this, run the electric fan continuously but only run the electric water pump 5 seconds of every minute. Keep track of the time necessary to cool the engine to 160°.
Next time start at 200° but run the fan and pump continuously until the engine is at 160°. I'll bet the cool-down time is far shorter than before.

It's interesting that people know that cooler air will extract more heat from a radiator than warm air but don't understand why. This is explained by Newtons Law of Cooling, which states: "For a body cooling in a draft (i.e., by forced convection), the rate of heat loss is proportional to the difference in temperatures between the body and its surroundings." This means that increasing the difference in temperature between the hot water and cold air will result in greater heat loss. If the air temperature is held fixed and the coolant temperature is increased, the effect is the same as holding the coolant temperature constant and decreasing the temperature of the air. The equation looks like this:



How much did the installation of your restrictor affect the flow? Do you think there would be other effects also, like increased head pressure and more system turbulence?

call Be Cool or Griffin. They are the ones that pointed me in the direction of slowing down coolant flow.

From Be-Cool FAQ's:

7) Q. Should my water speed be decreased?

A. No! Avoid using underdrive engine pulleys which slow water speed.

29) Q. Any specific thermostat recommendations?

A. Yes. Use a high quality, high performance thermostat like Be Cool's 78000 series thermostats. These units increase water flow and guarantee proper function.


From Griffin FAQ's:
5. Thou shall use the proper water pump pulley ratio.
To obtain the maximum operating efficiency rate for your water pump at highway speeds, you should overdrive the pump by 30-35%. Check your pulley selection. Most after market pulleys are a 1:1 ratio. For a 30-35% overdrive, the crank pulley should be approximately 7 7/8” and the water pump pulley approximately 5 3/4”. This overdrive provides proper coolant flow from the engine and through the radiator.
 

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closed loop

Then you would have one like in the pre 70's cars.... exactly. like 62-67 novas.
That is why I said that. As far as closed loop goes, I was reffering to the system being closed, with no venting....... Like when you set-up a vacuum pump motor. It must be set up closed loop.....No Venting.

If it has venting it isn't closed loop. That's all I was saying.

Read my other post from above and you will see why the slowing of circulating coolant worked for me I guess. Apparently, it is possible to flow coolant enough to cavitate it. So it will benefit from slowing the flow down.

So don't say that more circulation is always better.
And the guys at Be Cool and Griffin were the ones that pointed me in that direction.

Whether you want to believe they told me that or not.

David
 

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Discussion Starter #9
I am beginning to believe that Notanova is correct. It seems like the coolant is moving so fast through the system that it does not have time to cool down. You can watch the temp gauge from startup increase in temp to about 200 then the thermostat opens and you can watch the temp fall to about 160 and then start to climb back up to 200 and then on up as I drive farther on the hwy. It seems that it will handle that temp for about 10 or 15 miles and then it starts to climb like the water is just getting hotter and hotter as it circulate through the system.
Notanova where did you get the Moroso coolant restrictor kit...


Shane65 I have no vacuum advance or carb.. I'm running TPI.. I am running my timing at 10 degrees.
 

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Mitchc said:
I am beginning to believe that Notanova is correct. It seems like the coolant is moving so fast through the system that it does not have time to cool down. You can watch the temp gauge from startup increase in temp to about 200 then the thermostat opens and you can watch the temp fall to about 160 and then start to climb back up to 200 and then on up as I drive farther on the hwy. It seems that it will handle that temp for about 10 or 15 miles and then it starts to climb like the water is just getting hotter and hotter as it circulate through the system.
Notanova where did you get the Moroso coolant restrictor kit...


Shane65 I have no vacuum advance or carb.. I'm running TPI.. I am running my timing at 10 degrees.
normally speaking if a car can sit all day idling but over heats when driving down the road it is a coolant flow issue....and normally it is not enough flow that is causing the problem...conversely if it sits in the driveway and overheats but can drive down the road and not over heat normally speaking that is an airflow issue that is causing the problem...and you need to look at your shroud, fan, and how far your fan is set into your shroud, etc, etc.....

BTW you said you dont have vacuum advance but your initial timing is only 10 degrees advanced....that sounds really low cause normally you have to make up for the lack of vacuum advance...so 20 or so is normally a ball park figure.....BTW retarded timming can cause overheating...so possibly that is a place to look too.....just my 2cents:)
 

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I run no thermostat at all on my 350. I know I should but it will overheat in a minute if I do. Timing is correct and car runs great. Car run 180 on the high way on a 90 degree day all day long. If I do a cruise and we get bogged down the temp may go up to 210. Then as soon as I can get a little air in her she back down again to 180. I dont claim to know why this motor will run like this, but it has for going on better then four years now. When I changed over from cast iron heads to my Edelbrocks I was thinking I might have to install a thermostat. That was not the case. If anything it runs cooler. All I am trying to say is this worked for me. I am not saying it would work for you.
 

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I would like to hear more discussions regarding this.

My car gets hot on the highway. Usually takes about 10-15 minutes of highway speeds before the temp starts climbing. It will sit at about 190 deg on the highway, then after about 10 minutes it climbs to 200deg , 5 min later it is 210 deg. I get off an exit nad it starts to climb so I'm having to find the nearest gas station.:confused:

I have a 406, 10.5:1 compression, brand new 4 core factory replacement radiator, 160 deg thermastat, 3" chrome fan shroud, graphite flex fan. I do have a fairly large trans cooler in front of the radiator. I wondered if this could be causing the issue.

My lower hose does not have the wires in it. It was a GM lower hose I bought from Classic Industries. How can I check to see if it is collapsing?

What gets me is this motor didn't run hot in my last car. I had a 6cyl radiator, 5" chrome shroud and a large clutch fan.:confused: :confused:

I don't want to drive the car until I figure out how to make it run cooler. Any input is greatly appreciated.

Dave
 

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FunkyNova66 said:
I would like to hear more discussions regarding this.

My car gets hot on the highway. Usually takes about 10-15 minutes of highway speeds before the temp starts climbing. It will sit at about 190 deg on the highway, then after about 10 minutes it climbs to 200deg , 5 min later it is 210 deg. I get off an exit nad it starts to climb so I'm having to find the nearest gas station.:confused:

I have a 406, 10.5:1 compression, brand new 4 core factory replacement radiator, 160 deg thermastat, 3" chrome fan shroud, graphite flex fan. I do have a fairly large trans cooler in front of the radiator. I wondered if this could be causing the issue.

My lower hose does not have the wires in it. It was a GM lower hose I bought from Classic Industries. How can I check to see if it is collapsing?

What gets me is this motor didn't run hot in my last car. I had a 6cyl radiator, 5" chrome shroud and a large clutch fan.:confused: :confused:

I don't want to drive the car until I figure out how to make it run cooler. Any input is greatly appreciated.

Dave



just my 1 cents worth....

Since at highway speeds your getting just about as much air being forced through the rad as the rad can handle that to me would rule out the fan and shroud (especially since you can drive around town (low speeds) without over heating....IMO they are doing their job) So I would "think", again JMO, it could be one of two things....your water pump is not quite up to task with the heat the motor generates at crusing speeds(likely IMO...pump up the volumn as they say:D)...or your rad is not quite up to task(less likely as a 4 core factory rad should be able to handle a BB.....but still a possibliity)......BUT with all of that said I would get a different lower rad hose (one with a wire in it) and see if that solves the problem first...its the easiest and cheapest of the options to try....

All of the above is just my 1 cents worth...:)


EDIT: BTW I think the clutch fan of your previous setup was way supperior to the flex fan you have now....depending on if the clutch fan was thermostaticly controlled it may have actually been forcing slightly more air through the rad then normal (at highway speeds) and preventing the motor from heating up.........just speculation....I just personally dont like flex fans
 

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I had an overheating issue too. It would only heat up on the highway. Oddly enough, and contrary to popular belief, the answer was my factory fan was on backwords! :eek: I guess it was pushing air away from the radiator instead of towards it while going down the road. Sometimes it's the stupid things.

Kev
 

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If it has venting it isn't closed loop.

The 'closed loop' refers to the cooling loop and the use of the radiator to cool and recirculate the coolant. If it was an open loop system there would be no need for the radiator, you'd just stick your garden hose into the pump inlet and the hot water would would be pumped out into the street. The vent is just a safety device, to prevent catastrophic failure in case things get too hot. If we were to use your definition of 'closed loop' there isn't a closed loop system in existence, as none are welded up entirely. I design control systems for closed loop steam plants and there are vents and safety valves in many places to prevent damage of the system.

Apparently, it is possible to flow coolant enough to cavitate it. So it will benefit from slowing the flow down....So don't say that more circulation is always better.


You're trying to tell me that a cavitating pump will move more coolant than one that is not cavitating? My experience with pumps and pump controls would lead me to discount this assumption. Cavitation is so called because the fluid being pumped develops cavities due to reduced pressure and other effects. It doesn't occur in the radiator but inside the pump. I don't doubt that your temperature gauge indicates a cooler temperature, but it isn't due to decreased flow through the radiator. If the pump cavitates, the volume and outlet pressure is reduced and allows the formation of steam bubbles and hot spots in the engine due to the decreased vapor point. As the vapor point is reduced, the heat capacity is reduced and the coolant doesn't remove as much heat from the engine on its way through. If the water in the radiator has less heat in it, the radiator is less efficient and the engine gets hotter and hotter. Eliminating the cavitation increases the flow and cools the engine more efficiently.


I am beginning to believe that Notanova is correct. It seems like the coolant is moving so fast through the system that it does not have time to cool down.

How did Notanova measure the flow rate through the radiator? He didn't. He just assumed that the flow was less.

There is no 'time' in a closed loop system, each molecule of water spends the same average amount of time in the radiator no matter what flow rate is used. Your mission is to have the most heat in the radiator you can get in there, and as soon as a molecule loses any heat it becomes a less effective cooler. You want to get this molecule out of there quickly and replace him with one that has more heat. If a unit of water had 100 units of heat and lost half of them each second, it would lose 50 in the first second, 25 in the next second, 12.5 in the next, etc. The longer I keep this unit there, the less efficient it becomes. This is why a thermostat opens when the engine gets hot, to allow for more flow and more exchange of heat.
The effect of flow is shown as a temperature gradient across the system, the lower the flow, the higher the gradient. You don't want the engine inlet to be too cool or the outlet to be too hot.

Here's a calculation from the Stewart Components site:

Following is a typical engine:

* Inlet temperature = 180° F
Outlet temperature = 190° F
Coolant flow = 100 GPM
Specific heat of coolant = 1.0
1 HP = 5.2769885 GPM/°F
{ (Outlet-Inlet)CS} / 5.2769885 = HP loss
{(190°-180°) 100*1.0} / 5.2769885 = 189.5 H


If you were cruising down the freeway at 55 mph in this car with the pump running at 20 gpm and producing 60 flywheel horses, what would the temperatures look like?

Typical engine efficiencies at 60 flywheel horses requires you to dissipate about 20 hp in the radiator. If you do the calculation, there is about a 5° difference between the inlet and outlet temps.

If you were to speed up to 110 mph with a linear increase in rpm and pump gpm what would the temperatures look like? Since it takes about 4 times the power to go twice as fast, the fwhp would be 240, the radiator would need to dissipate 80 horses and the pump gpm would be 40. Plugging this in shows about a 10.5° difference in the inlet and outlet temperatures. Your temperature gauge would indicate about 5° hotter. If the pump was limited to 20 gpm, the gauge would indicate about 15° hotter.
 

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One other point. I didn't have this problem when I first built this set up but it was much cooler outside in feb/mar. It was having a hard time maintaining to 160 deg. Once it got hot outside, I noticed the temp creeping up on the highway and at idle.

I'll check the timing tonight and see where it is set. The distributor might have walked some since the hold down doesn't get real tight.

So...here is my plan in order: (please tell me if I am approaching this wrong).
  • Relocate sender to intake. It currently is in the side of the head....
  • Check timing
  • Replace Thermastat with high flow thermastat and make sure it is not installed upside down.
  • Replace the lower hose with a wire lined one like 69NovaSS suggested.
  • measure pulleys to see if they are not properly overdriven (20-30%) like Mike Goble suggested
.

If this doesn't work:
  • Buy a Be-Cool radiator with built in electric fans and call it a day.
If this doesn't work:
  • Drive car off cliff!:eek:

Dave:D
 

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I'm using the summit universal aluminum radiator and can run all day on the highway at 100deg day and it doesn't overheat.
I noticed when I had the manual switch for my 16" electric fan the engine would run a degree or so hotter with the fan running. It cooled better with the fan off doing over 50 or so.

When you say high way speeds what rpm are talking about? Mine is around 2,000 to 2,600 rpm. at 50 to 75mph.
 

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NEVER FINISHED64 said:
I'm using the summit universal aluminum radiator and can run all day on the highway at 100deg day and it doesn't overheat.
I noticed when I had the manual switch for my 16" electric fan the engine would run a degree or so hotter with the fan running. It cooled better with the fan off doing over 50 or so.

When you say high way speeds what rpm are talking about? Mine is around 2,000 to 2,600 rpm. at 50 to 75mph.
I'm talking 3,500 RPMs at 65 MPH in 90+ deg weather :eek: Does yours run hot in traffic on 100 deg days with the aluminum radiator and electric fans?
 

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FunkyNova66 said:
I've also heard temps from the head sender is sometimes 30 deg hotter than the intake. Is this true?
ya I've heard the same thing...but it was only about 20 degrees...whatever it is there is suposedly a difference between the two locations :)
 
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