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Losing Your Cool: 9 Cooling System Myths and Mistakes — and Why to Avoid Them!

 

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There are many myths and misconceptions about engine cooling, but the truth is your engine’s cooling system must perform a balancing act. It needs to extract enough heat to keep your engine happy, yet maintain enough heat to keep it operating efficiently. That means keeping the engine in the 180- to 210-degree F range.

To achieve and maintain optimum temperature range, a good cooling system needs the right-sized radiator and fan combo. It must also have the appropriate water pump speed and coolant flow between the engine and radiator.

Typically, when engines overheat or run too cool, it’s because of these cooling systems myths and misconceptions. Here are some of the more common myths and mistakes and why you should avoid them.

Eliminating the Thermostat

One of the greatest — or perhaps worst — cooling system myths is that you can remove your thermostat to eliminate overheating. This will only add insult to injury! When coolant never has a chance to give up heat via the radiator, it gets hotter and hotter, especially if you’re stuck in traffic. And even on the open road, coolant never has a chance to park in the radiator long enough to give up heat energy to the atmosphere.

Never operate your engine without a thermostat!

Thermostat selection boils down to application. Although enthusiasts tend to choose a 160-degree F thermostat to treat overheating issues, the 160-degree thermostat was originally intended for alcohol antifreeze back in the day. The best thermostat for classic vehicle applications today is the 180-degree thermostat. If you’re experiencing overheating with a 180, you have deeper problems with other components. Late-model computer-controlled vehicles mandate the use of a 192- to 195-degree F thermostat.

Water is the Best Coolant

Another myth is that water is the best coolant.

This is true in terms of heat conduction; however, it is also the best source of corrosion. If you are using straight water, you should always add water pump lubricant and a corrosion inhibitor. Also, use a coolant enhancer like Water Wetter, which improves surface tension and heat conductivity.

Coolant manufacturers often suggest a 50/50 mix of ethylene glycol and water, which will protect your cooling system down to -34F. If you’re expecting temperatures colder than that, you need a block heater or a warm garage. Mark Jeffrey of Trans Am Racing in Southern California tells us he runs 100-percent ethylene glycol and no water without consequence and has been doing it for many years. His logic is coolant temperature runs only marginally higher and this approach eliminates any risk of corrosion.

If you opt for the 50/50 mix, you can buy antifreeze already mixed with water for the sake of convenience. If you’re going to run an ethylene glycol and water mix, it is suggested you run distilled water to keep minerals out of your cooling system.

Summit Racing offers you another coolant option known as Evans High Performance waterless coolant. This is the last coolant you will ever have to buy because it is permanent. You run 100-percent of it in your vehicle’s cooling system. Begin your Evans regiment with new hoses and cooling system components and a system that is bone dry. If you’re servicing a system with traces of ethylene glycol and water, the Evans Coolant Conversion Kit is the best way to get started.

Improper Coolant Filling

We’ve seen a lot of people either under-service or over-service coolant.

When you are servicing a cold engine, you should add coolant to one inch below the filler neck which allows for expansion as the engine warms. Coolant can rise as much as one inch as the engine warms up. Start your engine with the radiator cap removed and coolant one inch below the neck. Then, observe as the engine warms. Allow time for the thermostat to open and for the engine to burp any stray air pockets.

No Anti-Collapse Spring

There are those, including hose manufacturers, who believe you don’t need an anti-collapse spring in the lower radiator hose. The truth is, you must have an anti-collapse spring in the lower radiator hose if you have an older vehicle with a conventional cooling system.

Because the lower radiator hose channels coolant to the water pump and engine, it is susceptible to negative pressure and collapse at high rpm. The anti-collapse spring prevents that from happening. One hose manufacturer says you don’t need the anti-collapse spring because it was used only for factory-fill purposes. This has never been true because of the positive pressure on the lower hose during fill.

Always run an anti-collapse spring in the lower radiator hose.

A Faster Fan is a Better Fan

There are many myths regarding electric fans. One belief is the faster a fan turns, the better — which is not completely true. At high speed, the radiator slipstream should be strong enough to carry heat from the radiator. When air is moving too fast, you get into boundary layer issues where heat doesn’t get carried away because air isn’t actually touching fins and tubes.

You want air to move slowly enough across fins and tubes to where it carries heat away. At speeds above 40 miles per hour your engine doesn’t need a cooling fan. This is why a thermostatic clutch fan or electric fan works best.

More Fans are Better

Some folks believe more fans are better. But that isn’t completely true, either. You don’t really need a fan both behind and in front of the radiator. Ideally, you will have a fan behind the radiator that provides cooling capacity based on coolant temperature. If your vehicle needs two cooling fans, there’s a deeper problem than fan capacity.

Improper Fan Spacing and Shrouding

One rule we see broken time and time again is fan spacing and shrouding. In most cases, cooling fans should be shrouded for proper vectoring of air velocity through the radiator. We recommend you pay close attention to what the factory does in any application.

Overlooking the Radiator Cap

Aftermarket radiators are popular upgrades, but you should also pay attention to your radiator cap.

Your coolant is under pressure to keep the boiling point as high as possible. That’s why you you want the highest pressure cap rating suitable for your application. Caps for older vehicles should be rated for 7-12 pounds; newer vehicles should have radiator caps rated to 12-18 pounds.

Cheap is Cool

It’s cliché, but you get what you pay for. When replacing cooling system components such as hoses, the water pump, and thermostat, don’t do it on the cheap. Spend good money on the best components and sleep better. Goodyear Super Hi-Miler cooling system hoses last longer than your average off-the-shelf hose, especially when paired with high-quality worm gear clamps.

You can find a wide variety of water pumps for nearly every application imaginable. Regardless of what brand of pump you choose, always opt for a high-flow water pump and be mindful of pulley ratio (pump speed).

Now that you know what pitfalls to avoid, scroll through the slideshow below for some valuable tips on choosing cooling system components.

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Always have some kind of coolant recovery system going. When you vent coolant to the pavement you are putting animals at risk as well as your engine from coolant loss. Antifreeze is toxic and dangerous to animals. They love the sweet taste and it can kill them.

The OEM was never much on cooling capacity with two-row core radiators. That’s why a three- or four-row core radiator like this one from Summit Racing Equipment increases capacity without any special modifications. It is a drop-in replacement for your lame factory original.

Aluminum radiators are popular for motorsports. However, did you know they make terrific drop-in replacements for factory copper/brass radiators? You can leave this as they are or paint them a satin black and no one will know the difference.

Truly the best heat exchanger is a crossflow radiator, which allows for better heat transfer to the atmosphere. Crossflow radiators became more common around 1970 and have been commonplace ever since. Installing a crossflow radiator in a classic vehicle originally designed for a conventional flow radiator can be tricky. Never install a radiator metal to metal. Always have some form of soft support.

Radiator caps are available in many forms from Summit. Choose a cap based on pressure and how much pressure is desired. Older cars and trucks like lower pressures in the 7-12 pound range. Newer vehicles are more in the teens.

The endless debate over anti-collapse springs ends with this. Bottom radiator hoses on vintage vehicles must have a stainless or galvanized steel anti-collapse spring. An anti-collapse spring keeps the lower radiator hose from collapsing at high rpm when the water pump causes negative pressure and hose collapse. If you experience overheating on the highway and normal cooling in town, you need an anti-collapse spring.

Opt for the best stainless steel worm gear clamps you can buy. Summit can help with that. If you’re going racing, double up hose clamps with two at each end of the hose.

Coolant filters, installed in the upper radiator hose, are a great idea especially with new engines where iron and aluminum particles can clog radiator tubes. The Gano filter is a good investment in durability and you can see what’s inside. There’s another coolant filter from TRAP, which has to be opened for inspection. If your engine starts running hot over time, check the coolant filter.

Always use brass freeze plugs with the deepest dish for best results. Most builders use RTV sealant to secure freeze plugs. Marvin McAfee of MCE Engines in Los Angeles uses JB Weld to secure these plugs. He also opts for screw-in oil galley plugs in all locations. Racing applications get retaining screws at all freeze plugs.

Summit offers a variety of high flow water pumps from Edelbrock, Weiand, and other aftermarket brands. Aluminum water pumps save weight and they conduct heat better than iron. Be mindful of forward and reverse-rotation water pumps. Reverse-rotation water pumps are serpentine belt driven.

It is those invisible things we don’t notice immediately that can cause overheating. The word FRONT on a head gasket means exactly that. Small block Fords, as one example, are unforgiving of improper head gasket installation because you will block cooling passages. Sometimes, rebuilders will knock freeze plugs inside the block during disassembly and leave them there, which blocks coolant flow. Be mindful of machining trash inside a block and heads. It will disturb coolant flow.

Here’s another gotcha…intake manifold gasket installation. Cooling passages must be clear between intake manifold and cylinder heads. Sometimes gasket cooling passages must be trimmed to allow coolant flow.

The most efficient cooling fan is the thermostatic clutch fan. It engages only when it is needed and free-wheels when it isn’t. At speed, the fan isn’t needed. Slipstream air through the radiator handles the cooling.

Although this six-blade fan is quick and effective, it is also inefficient and noisy. If you’re going racing or live where it gets extremely hot, this fixed-blade fan answers the call of heat. Also note this fan is properly positioned halfway into the shroud.

Pulley ratio is crucial to proper water pump and accessory operation. It is advisable, depending on what type of vehicle you have, to have a 1:1 ratio between crank and water pump pulleys. Check your manufacturer’s specifications for proper pulley sizing.

We like this groovy accessory drive package from Trans Am Racing for small block Fords. It is a serpentine belt drive, yet conventional. Note the 1:1 crank to water pump pulley ratio.

Few things beat an electric fan for operational quiet and efficient function. This is the Flex-a-Lite 15-inch 3,000cfm electric fan for a wide variety of radiators in the 20-inch range. Electric cooling fans should get switched power with ignition on only. Always use a fan relay kit in the interest of safety. These fans pull a lot of amps.

Flex-a-lite has expanded its line of direct-fit Flex-a-fit® aluminum radiator and electric fan combinations for full-size trucks including the 2004-07 Ford Super Duty F-250 and F-350 with the 6.0L PowerStroke turbodiesel engine. You can get yours from Summit. This is really a nice package that includes a clutch-fan emulator that plugs into the existing control system, sending feedback to the truck ECM and avoiding potential check-engine codes.

Check this out — Flex-a-Lite’s new #185 radiator/fan combo for the 1979-93 Fox body Mustang from Summit Racing. The Mustang X-TREME® electric fan moves 3,300 cubic feet per minute, draws up to 18 amps and dissipates over 50-percent more heat than competitive 16-inch fans. This entire unit measures 21 ½” x 17 ½” x 4 3/16”, covering over 45-percent more radiator surface than the original Mustang electric fan.

Flex-a-lite introduces a solid performance cooling solution for the ’87-’01 Jeep Cherokee (XJ) from Summit. This new radiator/fan combo featuring a two-row core replaces the stock cooling system without any modifications. When you opt for the electric fans, you get three 10-inch electric fans, moving a total of 2,400 cfm of airflow.

Coolant recovery systems from Summit are many and there’s one right-sized for your car or truck project. We like this compact coolant recovery tank #70053 from Be Cool. It is easily installed in most engine compartments or you can even hide it in a fender well with easy access for servicing.

This Canton coolant recovery tank from Summit can be fastened to your radiator or fan shroud with room to spare. The site tube makes observation easy.

Although the Canton #80-231 coolant recovery tank is designed specifically for the Mustang, you can engineer this piece to fit your application. It hugs the fan shroud and is easy to service. This is a 1967-70 Mustang fan shroud for the large 24-inch radiator.

If you’re dealing with tight quarters, this universal coolant recovery catch can is an easy install. What’s more, you can install as is or paint/powdercoat to your liking.

Have you tried Evans waterless coolant from Summit? This is the coolant you will never have to change — ever. Evans Cooling high performance waterless engine coolant is a proprietary base fluid with a specially-formulated inhibitor package designed for all gasoline, light-duty diesel, LP, and CNG engines. Evans contains no silicates or phosphates and requires no supplemental coolant additive. This coolant has a boiling point of 375 degrees F and will not vaporize--eliminating overheating, boil-over, and after-boil. The low vapor pressure reduces stress on the engine cooling system components. Evans Cooling high performance waterless engine coolant will also eliminate corrosion and offers protection to temperatures as low as -40 degrees F. Before you service with Evans, your water jackets must be completely dry.

Few of us ever think about this aspect of engine cooling, but did you know engine oil is also a coolant? If you disagree, consider this: your engine can run for a time without coolant. It cannot run very long without oil. Not only does engine oil lubricate, it carries heat away from the hottest surfaces in your engine. Synthetic engine lubricants are simply better for your engine because they can withstand higher temperatures and last longer between oil changes.

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16 Comments

  1. Pingback: Losing Your Cool: 9 Cooling System Myths and Mistakes — and Why to Avoid Them! - The Flat Spot

  2. Bart Logan says:

    Opening a myth’s story with a myth? The thermostat does one thing and one thing only. It regulates the MINIMUM water temperature. The “slowing down the coolant” myth is a leftover from the Flathead Ford days when it was necessary to force coolant to flow at the rear of the motor. While it is important to use the proper thermostat to ensure that the engine reaches proper operating temperature for more efficient combustion and lubrication, the elimination of the thermostat, in itself, not only will not but, by the laws of fluid thermodynamics in a closed system, CAN NOT cause overheating. What it WILL do is reduce the temperature differential between the hottest and coldest points in the system. With my regards to the esteemed Mr. Smart and the myriad of folks who will swear on a stack of Bibles that this has happened to them I shall now don my “flame suit” and return to my laboratory.

    • Amen. I was just about to correct them also and saw your comment first. Unbelievable they posted an article specifically to bust myths and actually included two. Their other point that is incorrect is their belief that slower air past radiator fins cools better than fast air. Where do they find this crap?

      • Slower air DOES cool better. Heat transfer takes time. There’s a reason a single combustion cycle in an engine is considered adiabatic; there isn’t time for it not to be.

        Faster air causes turbulence as you pass the Reynolds number of about 10000, depending on the application. A turbulent boundary layer means worse cooling. Period. There’s a reason all the manufacturers shut off their fans at high speed now. You’re TRYING to keep it laminar as often as possible.

    • 3 pieces of misinformation here:

      1. The idea that removing the thermostat causes the coolant to move so fast that the heat can’t be disappated because the water isn’t in the radiator long enough?

      One only needs to look at the engine side to expose this nonsense, if the water is going too fast for heat transfer, it’s not going to be able to extract any heat from the engine either with the result the water would stay cool and the engine heating up into a red hot block……..Doesn’t happen!

      The faster the water moves through the system, the more heat can be transferred, that’s what the thermostat does, controls the rate of coolant flow. It does get to a point when no further increase in flow will create any further cooling rather than faster flow impeding cooling.

      2. The same nonsense with the fan statement, faster air flow creates more cooling, always!

      3. Water is not the best conductor of heat, it does however have one of the highest heat capacities of any fluid. Putting other coolants in systems that were originally designed for straight water(cars before 1970) requires either bigger radiators or increases in water pump speeds to create the same cooling when 50/50 mixes of water/glycol are used.

      • Good Lord. No.

        As a general rule, ρAv=ρAV. So the significantly smaller tubes in the radiator mean significantly higher speed. There’s a reason the tubes are so long. It takes time to transfer heat. Similarly, metal to water isn’t the same as water to metal to air.

        Faster air creates more cooling always? Go look at the Red hot space shuttle and try that statement again. Faster air creates more HEAT always. If you have shear, due to speed of the flow causing turbulence, you’ve lost heat transfer capacity. Period.

        The third point is taken out of context. They say, specifically, that it’s the best COOLANT in terms of heat transfer. There are plenty of materials that have higher conductance, but they aren’t *coolants.* Especially not when used in the context of automotive engines.

    • I’m an aerospace engineer. We’re uh… Pretty well trained with fluid dynamics.

      You should try taking fluid dynamics past high school physics.

      Your claim is that since heat cannot, if itself, pass from body to a hotter body, that elimination of the thermostat cannot mean overheating. Except the engine is ALWAYS hotter than the coolant. The entire idea is to distribute the heat throughout the cooling system, mainly the radiator, to *reduce heat in that system.* You WANT your engine as hot as possible.

      The thermostat is an object in the flow. It will absolutely be a restriction. Thus slowing down the flow.

      There’s a reason they hire us to design engines and cooling systems. It’s more in depth than Bernoulli.

  3. Thank You for publishing this article. I’ve been buildings Engines for some 35+years,10 of which was in Daytona Beach;Florida.Being from New York[which was tough enough] I always believed in installing a 195 degree thermostat,not only for heating reasons but to maintain a complete balance across the whole Engine.Down south for some reason there convinced because they don’t need that much”Cabin Heat” you don’t need a thermostat.{These are the same People who refer to Engines as “Motors”}Every engine I’ve ever disassembled without a Thermostat was all “Gunked” up inside.Removal of a stuck closed thermostat along side the road is OK to get you where your going. I had myself a 440 Mopar with a stuck thermostat;in Florida no doubt, on I-4,,started over heating in traffic,, I pulled off to the shoulder,,Popped the stuck thermostat out,,,made a gasket,,,let it cool down for 45-60 minutes,filled it with water, got back on the road started cruising down the road,{traffic let up} and started it overheating,,4 Core Radiator,full of water,,,but the water was flowing to fast to allow the proper heat exchange for optimum cooling. So,YES a Thermostat is very important!
    MotorHead~Ty

  4. Tom Paparounis says:

    Ok. Maybe I can help with this one. How can it be that if you slow down the flow through the radiator, the engine will run cooler? Look at it this way, if you slow down the flow through the radiator, you also slow down the flow through the engine too. Therefore, the engine heats the water even more right? The 440 was an engine that could overheat in a heartbeat. I think they all had inadequate cooling systems,

  5. William Madore says:

    Use to install smaller size washers instead of thermostat in Stock Car, car never overheated, worked for me and the car, low cost repair.

  6. Richard Livers says:

    Don’t forget air restrictions. If you are changing the grill and crowding the engine compartment in a resto-mod application, adding fans, headers and HP, any restrictions can cause big issues. All of the items above are important and each one will affect the temperature in one way or another. I put vintage air in my resto Mustang, and can watch the temp gauge climb the minute I turn the compressor on.

  7. 195 degree thermostats exist for emissions reasons only. What a lot of people forget is that if you actually want your car to run cooler you have to adjust the fan system/ecu to account for it. Otherwise, you’re just changing the initial temp the thermostat opens at, not the overall operating temp of the engine.

    • stlwordpress says:

      No. The thermostat controls how much of that cooled coolant comes back into the engine, it doesn’t matter if there are huge fans cooling down the radiator. The water inside the block controls the operating temp of the whole engine. True the oil in the sump will not be as hot, but in most situations this is not a consideration. There are extremes of this and certainly older trucks in cold climates run radiator blinds to keep the whole of the engine warmer.

  8. Pingback: 2016 Top Tech Articles (Year in Review) - OnAllCylinders

  9. “For car owners or those that are not really into cars car maintenance may sound daunting especially for high tech cars.
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