Still overheating and it makes no sense!!!
05-02-2007, 01:18 PM
#1
Safety Car
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Still overheating and it makes no sense!!!
I am pulling my hair out over this. The car can sit and idle in the driveway for 20 minutes and never get higher than 180*. I can then take it out on a long drive and still never gets over 180*. This tells me that I don't have an air flow or T stat problem I think. But if I allow it to get to 180* and then shut the car off which naturally causes a spike in temp usually to about 210 the cooling system will not recover once I crank it up again. After cranking it up again and taking it down the road it will maintain the 210 but if I get into traffic or have to stop at a light it will spike again as high as 250 and will barely go down from there. I am running a Dewitt's BB aluminum radiator with dual spal's set at 160* for low and 190* for high. Fluid is 70/30 water to antifreeze with a bottle of water wetter. Stat has been changed twice now running a Mr Gasket HP stat which I tested before I installed it. Ignition is @ 18* adv at idle and 36* all in @ 3000. Carb is set pretty close and may even be a littl on the rich side still. I have been told that the Victor series H2O pumps need higher rpms to ncrease flow. However why will it stay @180 idleing in the driveway for 20 minutes then taking it out and running it hard? I could understand an air flow or water flow problem if it was over heating during this time. It only over heats after it has set turned off for about 5-10 minutes.
Wade
Wade
05-02-2007, 01:36 PM
#2
Safety Car
What kind of gauge/sender combo is giving you these readings? Have they been verified?
What temp is the stat? Assuming it's a 180* unit, your fans are running all the time. Why do you want them running all the time?
What temp is the stat? Assuming it's a 180* unit, your fans are running all the time. Why do you want them running all the time?
05-02-2007, 01:43 PM
#4
Safety Car
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Guage is a New AutoMeter Pro comp with sender. The stat is a 180* stat. Not sure what you mean about the fans running all the time. They are programmed to come on at half speed @ 160* and full speed @ 190*. I tested the guage to eliminate that as the problem and it was fine. The over heating that occurs after the car has been shut off for a bit and then restarted shows the obvious symptoms like pushing the water out the over flow and excesive run on when you switch the car off. None of these symptoms occur if you start the car up cold and run it without switching it off and allowing the temp to raise. I have never experienced this type of problem before..
Thanks
Wade
Thanks
Wade
05-02-2007, 01:45 PM
#6
Team Owner
Maybe you got air in the cooling system 
I'm running a El Cheapo $50 chinese (ProComp Electronics) aluminum water pump (+35% flow), a Griffin universal radiator ($159) and a Permacool 2950 cfm single fan ($100) and my yellow '68 runs between 175 - 190 degrees on a hot Florida day, even if sitting in stop and go traffic or at 90 mph on the highway...
Something is definetely wrong on your setup.. I'd say that it's either the water pump or air in the system.. The DeWitt's radiator and fans shoud keep the temperature right at 180 - 190 degrees..
Have you verified that the fans are ACTUALLY on above 190 degrees?
I'm running a El Cheapo $50 chinese (ProComp Electronics) aluminum water pump (+35% flow), a Griffin universal radiator ($159) and a Permacool 2950 cfm single fan ($100) and my yellow '68 runs between 175 - 190 degrees on a hot Florida day, even if sitting in stop and go traffic or at 90 mph on the highway...
Something is definetely wrong on your setup.. I'd say that it's either the water pump or air in the system.. The DeWitt's radiator and fans shoud keep the temperature right at 180 - 190 degrees..
Have you verified that the fans are ACTUALLY on above 190 degrees?
05-02-2007, 01:53 PM
#7
Safety Car
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Where could the air be coming from? I verified that the fans are coming on at the programmed temps. I guess I am assuming that they are coming on after I start the car the second time. I will verify that this evening.
Wade
Wade
05-02-2007, 01:56 PM
#8
Does your radiator cap fully seal?
Are you running an expansion tank plumbed to allow the rad to suction coolant back in the system?
Are you running an expansion tank plumbed to allow the rad to suction coolant back in the system?
05-02-2007, 01:58 PM
#9
Team Owner
If you just run a hose from the radiator cap (for pressure relief), it is possible that air is being sucked into the radiator.
If you run a overflow tank, it would suck radiator fluid and not air into the radiator.
How many lbs is your radiator cap rated? is the VENT designation on the cap lined up with the vent?
It is possible that there's a air bubble in the system since you filled it up! The way that I eliminate air in the cooling system is that I let the car fun for 2 - 3 minutes with the radiator cap off (starting the car cold of course). If the fluid level goes down when the engine is running, then you got air in the radiator.. I usually let the car run for 2 - 3 minutes and top off the fluid as the car is running and when the level is not dropping anymore, I know that there are no more air bubbles in the system..
05-02-2007, 02:04 PM
#10
Team Owner
Did you put a high-capacity water pump on the engine? If so, you may not be letting the water stay in the radiator long enough to cool it down....just keep recirculating hot water through the engine. I know this sounds weird, but it can happen; once the system gets "too hot", it will not recover. Try putting a 160 deg thermostat in it. The heat spike at shut off should go much higher than 180. Maybe it will be OK with that set-up.
05-02-2007, 02:05 PM
#11
Team Owner
My fingers screwed up. My last post should say "the heat spike shouldn't go much higher than 180.."
05-02-2007, 02:05 PM
#12
Safety Car
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Thanks I will try starting it tonight with the cap off of the expansion tank and see what happens. The cap is vented and I am running an expansion tank. The radiator itself does not have a radiator cap. I also am not running a heater core so I know that is not the problem. Thanks for everyones input.
Wade
Wade
05-02-2007, 02:08 PM
#13
Team Owner
Thanks I will try starting it tonight with the cap off of the expansion tank and see what happens. The cap is vented and I am running an expansion tank. The radiator itself does not have a radiator cap. I also am not running a heater core so I know that is not the problem. Thanks for everyones input.
Wade
Wade
05-02-2007, 02:40 PM
#14
Instructor
Black Rat.... Your problem is caused by the coolant rising to a temp where it vaporizes in the pump, thus preventing the pump from circulating it. This can be caused by simply not having enough anit-freeze concentration and having too low of a boiling point, or by a pump with the wrong impeller geometry.
What happens is that the coolant rises to a point where it is on the verge of boiling, but it doesn't boil because of the pressure increase in the system, then you start it back up and the water pump is turning, it creates a low pressure area at the inlet of the pump. The coolant in that immediate area will boil, thus cavitating the pump and preventing actual circulation of the water. The harder you run it the more it will boil at the inlet of the pump.
I would try running a 50/50 mix to start with. If that doesn't work, I would try a stock water pump. Are your Spals set up to run when the engine is shut down? Many (or maybe all) OEMs set theirs up that way so that the coolant temp can't spike to a critical level after shutdown.
What happens is that the coolant rises to a point where it is on the verge of boiling, but it doesn't boil because of the pressure increase in the system, then you start it back up and the water pump is turning, it creates a low pressure area at the inlet of the pump. The coolant in that immediate area will boil, thus cavitating the pump and preventing actual circulation of the water. The harder you run it the more it will boil at the inlet of the pump.
I would try running a 50/50 mix to start with. If that doesn't work, I would try a stock water pump. Are your Spals set up to run when the engine is shut down? Many (or maybe all) OEMs set theirs up that way so that the coolant temp can't spike to a critical level after shutdown.
05-02-2007, 02:52 PM
#15
Safety Car
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Black Rat.... Your problem is caused by the coolant rising to a temp where it vaporizes in the pump, thus preventing the pump from circulating it. This can be caused by simply not having enough anit-freeze concentration and having too low of a boiling point, or by a pump with the wrong impeller geometry.
What happens is that the coolant rises to a point where it is on the verge of boiling, but it doesn't boil because of the pressure increase in the system, then you start it back up and the water pump is turning, it creates a low pressure area at the inlet of the pump. The coolant in that immediate area will boil, thus cavitating the pump and preventing actual circulation of the water. The harder you run it the more it will boil at the inlet of the pump.
I would try running a 50/50 mix to start with. If that doesn't work, I would try a stock water pump. Are your Spals set up to run when the engine is shut down? Many (or maybe all) OEMs set theirs up that way so that the coolant temp can't spike to a critical level after shutdown.
What happens is that the coolant rises to a point where it is on the verge of boiling, but it doesn't boil because of the pressure increase in the system, then you start it back up and the water pump is turning, it creates a low pressure area at the inlet of the pump. The coolant in that immediate area will boil, thus cavitating the pump and preventing actual circulation of the water. The harder you run it the more it will boil at the inlet of the pump.
I would try running a 50/50 mix to start with. If that doesn't work, I would try a stock water pump. Are your Spals set up to run when the engine is shut down? Many (or maybe all) OEMs set theirs up that way so that the coolant temp can't spike to a critical level after shutdown.
Thanks for the info. I doubt if I have anywhere near a 50\50 mix right now. probably much closer to 70\30 water or more. No the spals do not run after the engine is turned off. I need to look at the programmer manual and see if there is a way to do that.
Thanks!
Wade
05-02-2007, 03:15 PM
#16
Safety Car
Did you drill 2-3 holes in the outside edge of the stat to prevent the air bubble problem? Is there any way you can verify water flow when it is having the temp spike?
Are those Spals actually pulling air and not pushing it?
With no cap on the rad and a cap on the expansion tank, the excess coolant is forced into the tank when hot. This will compress the air in the tank, right?
With your on temp set at 160 and your stat at 180, your Spals will always run, at the very least, in low because your engine temp will never be below the stat temp. A better situation would be fans on at ~205-210 and then off at a temp slightly above the stat opening . Mine is set so that both fans come on at 205 and go off at 180. I run a 160 stat tho and my fans rarely run.
Brett
Are those Spals actually pulling air and not pushing it?
With no cap on the rad and a cap on the expansion tank, the excess coolant is forced into the tank when hot. This will compress the air in the tank, right?
With your on temp set at 160 and your stat at 180, your Spals will always run, at the very least, in low because your engine temp will never be below the stat temp. A better situation would be fans on at ~205-210 and then off at a temp slightly above the stat opening . Mine is set so that both fans come on at 205 and go off at 180. I run a 160 stat tho and my fans rarely run.
Brett
05-02-2007, 03:20 PM
#17
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Black Rat.... Your problem is caused by the coolant rising to a temp where it vaporizes in the pump, thus preventing the pump from circulating it. This can be caused by simply not having enough anit-freeze concentration and having too low of a boiling point, or by a pump with the wrong impeller geometry.
What happens is that the coolant rises to a point where it is on the verge of boiling, but it doesn't boil because of the pressure increase in the system, then you start it back up and the water pump is turning, it creates a low pressure area at the inlet of the pump. The coolant in that immediate area will boil, thus cavitating the pump and preventing actual circulation of the water. The harder you run it the more it will boil at the inlet of the pump.
I would try running a 50/50 mix to start with. If that doesn't work, I would try a stock water pump. Are your Spals set up to run when the engine is shut down? Many (or maybe all) OEMs set theirs up that way so that the coolant temp can't spike to a critical level after shutdown.
What happens is that the coolant rises to a point where it is on the verge of boiling, but it doesn't boil because of the pressure increase in the system, then you start it back up and the water pump is turning, it creates a low pressure area at the inlet of the pump. The coolant in that immediate area will boil, thus cavitating the pump and preventing actual circulation of the water. The harder you run it the more it will boil at the inlet of the pump.
I would try running a 50/50 mix to start with. If that doesn't work, I would try a stock water pump. Are your Spals set up to run when the engine is shut down? Many (or maybe all) OEMs set theirs up that way so that the coolant temp can't spike to a critical level after shutdown.
I learn something new everyday!
05-02-2007, 05:17 PM
#18
Melting Slicks
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I have an expansion tank on my 92 LT1 which works similar to yours. Definately drill a couple small holes in the side of your t-stat, this helps burp air from the system. Next have the front of the car higher than the rear, this also helps. With the radiator cap off of the expansion tank start the car and let it warm up until the t-stat opens and starts circulating coolant. Add coolant and replace the radiator cap. Make sure your cap is in good working order, if not replace with one with the proper pressure relief.
It definately sounds as if you have a circulation problem once the car has warmed up. You might try a 160 t-stat too. My fans are set to come on at 195 and off at 180.
Conversely to popular belief, a hi flow water pump helps cool better by flowing more water thru the radiator. For example a 160 t-stat will open at 160 and allow the water to be cooled and maintain a lower temperature. A 180 stat will start cooling the fluid at 180 and will try to maintain that temp by holding the coolant in the engine longer.
With my car set up this way it never sees 200 degrees. 180 to 195 is where it operates. I hope you solve your problem!
Bernie
It definately sounds as if you have a circulation problem once the car has warmed up. You might try a 160 t-stat too. My fans are set to come on at 195 and off at 180.
Conversely to popular belief, a hi flow water pump helps cool better by flowing more water thru the radiator. For example a 160 t-stat will open at 160 and allow the water to be cooled and maintain a lower temperature. A 180 stat will start cooling the fluid at 180 and will try to maintain that temp by holding the coolant in the engine longer.
With my car set up this way it never sees 200 degrees. 180 to 195 is where it operates. I hope you solve your problem!
Bernie
05-02-2007, 05:46 PM
#19
Team Owner
BerniesVette:
"Popular belief" is that the higher the water pump capacity, the better the cooling system. This is a false belief. If pump capacity is too high for the system design, the water will not be in the radiator long enough to let it cool sufficiently...not to mention that the pump is "working" harder than a lower capacity unit and adding more heat in the process. The pump needs to be "sized" to the system it serves.
"Popular belief" is that the higher the water pump capacity, the better the cooling system. This is a false belief. If pump capacity is too high for the system design, the water will not be in the radiator long enough to let it cool sufficiently...not to mention that the pump is "working" harder than a lower capacity unit and adding more heat in the process. The pump needs to be "sized" to the system it serves.
05-02-2007, 05:50 PM
#20
Le Mans Master
I have an expansion tank on my 92 LT1 which works similar to yours. Definately drill a couple small holes in the side of your t-stat, this helps burp air from the system. Next have the front of the car higher than the rear, this also helps. With the radiator cap off of the expansion tank start the car and let it warm up until the t-stat opens and starts circulating coolant. Add coolant and replace the radiator cap. Make sure your cap is in good working order, if not replace with one with the proper pressure relief.
It definately sounds as if you have a circulation problem once the car has warmed up. You might try a 160 t-stat too. My fans are set to come on at 195 and off at 180.
Conversely to popular belief, a hi flow water pump helps cool better by flowing more water thru the radiator. For example a 160 t-stat will open at 160 and allow the water to be cooled and maintain a lower temperature. A 180 stat will start cooling the fluid at 180 and will try to maintain that temp by holding the coolant in the engine longer.
With my car set up this way it never sees 200 degrees. 180 to 195 is where it operates. I hope you solve your problem!
Bernie
It definately sounds as if you have a circulation problem once the car has warmed up. You might try a 160 t-stat too. My fans are set to come on at 195 and off at 180.
Conversely to popular belief, a hi flow water pump helps cool better by flowing more water thru the radiator. For example a 160 t-stat will open at 160 and allow the water to be cooled and maintain a lower temperature. A 180 stat will start cooling the fluid at 180 and will try to maintain that temp by holding the coolant in the engine longer.
With my car set up this way it never sees 200 degrees. 180 to 195 is where it operates. I hope you solve your problem!
Bernie
