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As someone who just spent the better part of the last few months hunting down a cooling issue in my '82 C3, I would start with checking the "free" things.
Verify with IR Temperature gun on the upper radiator hose/thermostat housing.
Confirm lower hose isn't collapsing (if no spring present, you can get one for $10-$15)
Check the air dam (front spoiler) and air deflector (valance).
On a separate thread that I had tracking down the issue I have a few pics of my front spoiler and air deflector. The spoiler was trashed and the deflector was deformed. After replacing the spoiler and putting fixing the air deflector, my cooling issue seems to have been resolved.
Make sure foam is present around the radiator. Mine at least requires foam to be there.
Definitely recommend a better mix of coolant. Also, even though you've got the electric fans, it doesn't necessarily mean its getting air.
Your cooling system does not run at ambient pressure, it runs at 15 psi, or whatever your rad cap is actually doing. The boiling temperature of your coolant on a stove doesn't matter. You can run 100% deionized waterpurified (or soft) water if you want. Anti-freeze does two things. Its critical funciton is to lower the freezing temperature to prevent ice from destroying your engine. It also adds anti-corrosive chemicals to your coolant system, which you can add separately.
Here's a better chart. If your system is holding pressure, and functioning properly, you won't see those temps. During the summer, pure water will do a better job cooling your engine than any mix of antifreeze (see the article below). You can also add a higher-pressure rad cap. Guess what NASCAR does.
I have a 1968 Convertible with a L88 Clone engine under my hood. I am using the L88 Air Box under the hood to help my engine's Combustion air cooler which helps the engine. I have 12.25-1 compression and it tends to make the engine run Hotter as it works to make horsepower. I have an Aluminum radiator and a stage 2 Stewart's Aluminum water pump. I have a dual 11" SPAL fans on the aluminum shroud behind the radiator an controlled by a DeRale PWM Electronic Cooling Fan controller. This way the fans start at 50% speed and if the engine keeps getting hot the speed of the fans increases to compensate for the heat. I also have spent lots of time sealing the radiator to any airflow that might try to get in to go through the radiator.
The coolant is critical and if you are running 20% anti-freeze and 80% Distilled water you should be okay. I use 70% Distilled Water and 30% anti-freeze for my coolant with a 15 psi radiator cap. I also run at least one bottle of the Redline Water Wetter in the coolant because it really helps. It is not a "snake oil". If you are using more than 50% anti-freeze n Florida then you are not helping your car stay cool. I saw a small Asian car that was overheating badly, it turned out that it had 100% anti-freeze in the cooling system. Anti-freeze is not as good as water at transferring the heat.
One thing that pushed my engine's temperature higher was a bad vacuum hose connecting the vacuum advance had dry rotted and was leaking vacuum not allowing the timing to stay more retarded. Another possibility would be to be sure that you have an effective/working coolant overflow jar and the hoses connecting it. As the coolant heats up it expands and needs to have a place to go where it will be re-used as the engine cools down. The coolant needs to get to the overflow jar when it heats up. If everything is working the coolant will be drawn back into the radiator and the radiator will stay full. If the hoses are bad then the fluid can't be drawn back into the radiator which causes a large air bubble inside the radiator effectively forcing the coolant temperature up. The overflow system operation is critical to a properly functioning engine and a reliable car.
Thank you Bikespace for the great articles! I appreciate the time you take to share those articles with all of us! I will switch my Distilled water for the Reverse Osmosis water as I have a RO system in my home in Fairfax. Thanks again!!
ive always been told water cools better but you need the antifreeze and anticorrosive properties of the antifreeze.. This is why some people in the south either dont run much or any..
Another option is something called EVANS NPG Coolant. It is a great solution for HOT running engines. I used it in my 427 for over 20 years and the material is still working and in good shape. The fact that there is NO pressure in the cooling system really helps the components of the cooling system to last longer. I run a zero psi radiator cap and the system works. I have been checking the Ph of the coolant and it is still well within range. The NPG has the same ability of Water Wetter in that it removes the layer of tiny bubbles that form on the metal surfaces inside the cooling system. The layer of tiny bubbles actually block the transfer of heat and this is why the Water Wetter works as well as it does. If there is any remaining water left in the engine it should boil out of the NPG when the engine is warmed up.
The hardest part of using the EVANS NPG was getting every drop of water and any old coolant out of the coolant loop. Once done I filled the BB Radiator up with several gallons of ($$) NPG. The coolant does help keep the engine from getting too hot but it does run a bit warmer than the water did. Where my engine would run in the 200* range with pure water and about 210* for the NPG so it wasn't to bad. I also have NPG in my water cooled Motorcycle to help keep it cool.
In Florida I would run 70/30 with 70% being R/O Water and the 30% being anti-freeze if it were my Corvette. I would be absolutely sure that the Radiator Overflow system is working at 100% as this will keep air out of the radiator.
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I have seen that stuff before. But I can't justify the cost, especially if it doesn't run cooler than Prestone.
Amazon wants $103 for two jugs of Evans.
Better not have a leak with that liquid gold.
As far as water, never use tap water. Go to Walmart and get a couple jugs of pure distilled water.
No minerals, no calcium deposits, no lime, and very little rust.
It makes the worst coffee in the world but is the best choice for cooling system mix.
2020 Corvette of the Year Finalist (performance mods)
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You said it gets hot idle and less so moving. You have a coolant issue . It's not moving fast enough and it isn't getting cooled.
You need to make sure you are using full size pulleys and your fan is running correctly. If you are using a mechanical fan get I'd of it and the stock shroud. Get a dual fan setup with a shroud that has a gap behind the fins across the whole radiator while sealing completely on all 4 sides so there is air flow when the fans pull. The good ones have flaps that will open with highway speed air pushing against them but seal at slow beach cruising speeds.....
Idling engines aren't spinning the mechanical fan fast enough to draw air through the radiator adequately for big block heat. Especially with the big gaps around the shroud
. Also seal up the radiator and air box in front of the radiator so all the air scooped ininto that area in front of the radiator has to go through it. And if you are running an underwrite pulley cooling issues are your fault...you're not saving enough power to see any benefit.
My 427 with a 165 thermostat will stay below 180 on days below 70 all day long. Above 70 and it's stable at 185 to 195.
With aluminum in the system anywhere, you absolutely need a potent anti corrosive agent, or you will get electrolysis, and the aluminum will be sacrificed FIRST as the sacrificial anode.
This is why you must run ONLY distilled water in your cooling system, and why you can help prevent electrolysis by using a conductivity meter to help keep it at bay. Even soft water or reverse osmosis water is not good enough. Only distilled or deionized. If you run less than 50% antifreeze you MUST use other anti-corrosive measures to protect the aluminum. And especially that expensive and thin aluminum radiator! Those anti-freeze coolant mixes do not provide enough anti-corrosive protection for aluminum under 50%. Tap water will cause hardness scale in your rad, and anything other than distilled will accelerate electrolysis. Distillied water has no ions and will not conduct electricity at all, so it "breaks" that electrical circuit. As soon as there is some corrosion, ions are present and now it will conduct electricity. You have to keep it at almost zero on your meter to be protected.
Here is how to use a multi-meter that you probably already have to check the conductivity of the coolant, and tell whether you have enough anti-corrosives present, or you need to flush it. It might take you 1 minute to test it. The higher the reading you get, the more electrolysis corrosion you have going on.
As the (aluminum) metal starts to corrode, it will go first, metal particles get dissolved in the water, and then the water conducts electricity better, and then the process keeps accelerating. Until the rad leaks.
I have never seen a car that could not be cooled properly with 50% antifreeze. If it didn't it always had other issues that could be corrected. The primary purpose for not running glycol in a racing situation is that in many organizations is that it is BANNED. It is far too slippery and difficult to clean up after even a small leak or accident. You can run a good anti-corrosive package, without any glycol/anti-freeze, and distilled water, and it will work great. How much better will it cool? I never bothered to check for these other reasons. But one night below freezing will cost you dearly in cubic dollars. Is it worth the risk? It even freezes in Florida once in a while. I know guys on race teams that even slip-up on that one once in a while. So I do not EVER advise running 20% antifreeze, for any reason, because of the severely weakened anti-corrosion package, and I am a chemist.
Mixing and matching two different anti-corrosive packages together is ill-advised, as some do not play nicely with others. I suppose you could dig even farther into the chemistry to see if they mix ok, but isn't it even simpler just to fix the cooling problems airflow issues? with a stock copper rad, the thick iron block is the superficial anode, and the reason you get all those crudy deposits in copper radiators, that are so hard to clean out.
There are little zinc anodes you can add inside the radiator thru the cap to help, like on a boat, and they do help if you have a problem, but are usually not needed.
The alternator can accelerate the problem sometimes, so make sure all your engine, alternator, and other electrical grounds are good.
And if you ADD an aluminum rad to a car that never had one, I would strongly suggest you add a tiny little GROUND WIRE TO THE RAD, and ground it to the rad support, and make sure that grounds all the way back to the frame and the battery. (Because I do not think a C3 rad support normally does).
I used to teach this corrosion stuff for a living at a large industrial level. Not many people talk about this in the auto market and it is a shame. How many heater cores have you heard of that sprung leaks and needed replaced?
You will never even know you have a corrosion problem, until you have a leaky $1000 aluminum rad. In the old days, they used to eat out the thermostat housing necks on the intake manifolds, but that took longer because it was thicker.
To get into the technical side of the 50% antifreeze mix vs water debate we need to talk about thermodynamics of heat flow.
The heat capacity of ethylene glycol is 2.42 J/g K. vs water is about 4.20 J/g K.
That is a huge 75% difference but we need to talk about a 50% mix, that would have about 30% less heat capacity than water. So a cooling system of all water could get by with fewer quarts if it is all water.
Even then in a car cooling system, that value is kind of irrelevant. It only cover how much heat water can hold. IE: how long it will take until it heats up.
We need to talk about heat flow. At 180 degrees F, the difference in thermal conductivity between a 50-percent antifreeze to pure water, we see about 38-percent less heat transfer. So basically an all water system would conduct 38% more heat than a 50% mix system, if nothing else changed. (As long as it did not freeze.) That is pretty significant. Or an all water system could use a 38% smaller radiator. Basically the car manufacturers already designed in the radiator size, while considering the 50% mix. But with a more powerful motor, comes more heat.
In a southern climate, you could run pure water and get a substantially more heat flow, similar to putting in a much larger radiator. But I would still recommend only distilled water, not tap. You could add a lower amount of ethylene glycol, say around 30% to cover the lowest temps you would ever see there, like 5 degrees. (20% only goes to about 18-20*. that might not be enough. OOPS! that could get expensive). Then you are good freezing wise. That might cut your cooling advantage to 20%, but it is still an improvement. But I would add a full anti-corrosion package to protect the aluminum. There must be one out there that are recommended to be used with normal anti-freeze systems. But I do not know what brand that would be. It gets much colder here than that, so I haven't bothered, for street cars. And the race cars just go inside when it gets cold.
This is hilarious, the chemical engineer recommends more glycol for corrosion, the *presuming* mechanical engineer recommends higher water concentration for heat capacity. Everyone cares about their specialty. For my two cents, and as an electrical engineer, I gotta say glycol is a great dielectric lmao.
industry in a nutshell
but we all know the accountant reigns supreme
Alright so I have a 1979 corvette with a BBC 540 and I can’t get the thing to run cool.
I have a 4 core champion radiator running a 80/20 mix with water wetter added to it.
Dual maradyne electric fans with shroud about 3500cfm
Stewart stage 2 aluminum water pump with a march under drive pulley.
Timing is set at 18 initial with mechanical advance all the way to 38 at 3000rpm
165 thermostat that is operational and doesn’t stick(confirmed in boiling water)
Car runs great but temps consistently climb past 220 with ease. Am I missing something?
Has the car ever ran at the T-stat setting?
Can you get the temps of the radiator on the inlet and outlet tubs to see what the temp delta is?
Do you have an oil temp gauge and if so what are the oil temps when the coolant temps are above 220*?
The whole 'thing' about cooling C3's (especially big block C3's) seem to flag-up many interesting.....yet conflicting experiences. It would be nice to see a 'paper' on the logic/effectiveness of carefully selected cooling components that actually work togther collated from a knowledgable source.
My 20+ years of owning an early big block C3 have led me to understand potential issues relating to cooling. Radiator
Being as a C3 already has the maximum radiator surface area exposed to incoming cooling air, other than making sure the radiator is fully sealed to its mounting and fan shroud and that its physical condition is 100% the only options here seemingly are replacement perhaps with a OEM style aluminium radiator. Multi-Row Radiators.
If considering a new radiator (and perhaps a custom built unit) with one or more additional 'rows' would this create more of a restriction for cooling air to pass through?
Is there a calculation allowing for the potential reduction of cooling air passing (caused by the additional rows) and the possible change in internal coolant flow? Water Pumps.
Given that a multi-row radiator could reduce the flow of cooling air passing through - would the use of a higher performance (high volume) water pump be potentially detrimental in terms of effective cooling? Would coolant flowing internaly at higher speeds would be less likely to absorb heat from the radiator? Conversely - would a coolant flowing at lower speeds absorb heat from the radiator core more effectively? Mechanical Fans
The real limiting factor in cooling the C3 (certainly with higher performance engines) is actually getting enough cooling air through the 'nose' of the car and through the radiator. The use of an efficient fan and properly fitted fan shroud is essential. The OEM viscous fan set-up with OEM shroud (if in working order and fitted/sealed correctly) seems to be 'almost' adequate. Whilst aftermarket electric fan suppliers quote CFM figures there seems to be zero information relating to CFM performance of OEM 5 blade and 7 blade fans (as used with a/c cars). Additionally the OEM viscous fan couplings seem to be classed as 'Standard Duty', 'Heavy Duty' and 'Severe Duty' but with zero information relating to activation temperatures how would you select the best option? Electric Fans
Whilst electric fan set-ups seem to be a popular option - many installers seem to have issues relating to the electrical system controlling them. Are the fans as effective as we are led to believe? I'm sure the OEM mechanical set-up is far more efficient.
The logic of two relatively small fans affixed directly to the rear of the radiator with a minimal mounting frame simply drawing cooling air through two relatively small 'circles' (rather than than the whole radiator surface seems flawed and escapes me.....unlike the same calculation if cooling fans were spaced away from the radiator in a correctly designed shroud (as per OEM installation?).
05-17-2024, 11:31 AM
