Overheating, Coolant Leaks & Corrosion

DFC Diesel is presented as the sponsor/host brand for The Diesel Podcast. For listeners, it’s a clue that the discussion may focus on diesel-specific parts and service knowledge from a parts supplier.

Diesel emissions regulations can affect how engines are calibrated and what aftertreatment hardware is used (like exhaust treatment systems). Those changes can also influence cooling needs and how technicians diagnose overheating or coolant-related issues.

Start-stop technology automatically shuts the engine off when the vehicle is stopped and restarts it when you release the brake or press the accelerator. It’s used to reduce fuel consumption and emissions, but it can also change how components are stressed during frequent restarts.

The “regulatory side” refers to how government emissions and compliance rules drive what technologies automakers must design and build. Because product development takes years, companies often prepare for regulations before they’re fully finalized, which can lead to uncertainty and changing requirements.

A GPF (gasoline particulate filter) traps soot particles in gasoline engines, similar in purpose to a diesel particulate filter. Because it’s tied to emissions regulations, changes in rules can affect whether manufacturers need to use it on future vehicles.

Rizz loan (likely referring to the brand “K-Seal”/“Rislone,” but the transcript says Rizz loan) is discussed as an additives company with products that are used in the automotive market. In this segment, the host frames it as having additives that “go underneath” and work alongside Bars Leaks products for leak-stopping.

Bars Leaks is a well-known brand of automotive leak-stopping additives, often used for cooling-system leaks. Products in this category typically circulate through the system and help seal small leaks by depositing material where the leak occurs.

Kershaw Knives is mentioned as the sponsor/friend of the show offering a discount code. While not an automotive component, it’s part of the episode’s commercial segment.

The Lincoln Nautilus is a mid-size luxury SUV from Lincoln, built for comfort, quiet cruising, and family-friendly practicality. It’s the kind of vehicle that can come up when discussing higher-end pricing and what buyers get for the money. In the podcast context, the name “Nautilus” may also be referenced due to its historical associations, even though the car itself is a modern SUV.

The USS Nautilus is referenced as a historical topic, likely tied to the host’s interest in history. It’s not directly connected to diesel cooling or corrosion, but it’s a notable historical mention.

BarzLeaks is an additive brand that’s used to seal leaks by introducing a material into the system. In this story, it’s described as being circulated through a leaking cooling system and then acting as a long-term seal once it penetrates the leak area.

The transcript describes a “stop-leak” approach: circulating a sealing material through a system so it penetrates the leak and forms a seal. This concept is often used for small leaks, but it’s not the same as repairing the underlying cause (like a cracked housing, failed gasket, or corrosion).

“DF fluid” refers to diesel fuel–related fluid used in many modern diesel systems (commonly diesel exhaust fluid/DEF in the broader industry). The key point here is that the fluid’s chemistry and temperature behavior matter—if it crystallizes, it can be hard or impossible for the system to dose correctly. That can lead to performance issues and warnings until the fluid is handled correctly.

Crystallization is when a fluid changes from a liquid into solid crystals, usually due to temperature and/or contamination. For diesel-related fluids, crystallization can block dosing and cause system faults because the equipment expects a pumpable liquid. This is why storage conditions and fluid quality matter.

A diesel truck’s cooling system keeps engine temperatures in a safe range so the engine can last. It relies on coolant circulating through passages, a radiator, and a thermostat to move heat out of the engine. When owners ignore it, overheating and internal damage can follow.

Coolant is the fluid in the cooling system that absorbs heat from the engine and transfers it to the radiator to be released to the air. Over time, coolant can degrade, lose corrosion protection, and become contaminated, which raises the risk of overheating and leaks. Many owners only notice coolant when a shop flags it during routine service.

Corrosion is the chemical/electrochemical deterioration of metal surfaces inside the cooling system. When coolant degrades or the wrong coolant is used, corrosion protection can weaken, allowing rust and pitting to form. This can clog passages and contribute to overheating and coolant leaks.

In diesel emissions systems, regeneration is the process of burning off accumulated soot in the exhaust aftertreatment system. It typically raises exhaust temperatures, which increases heat load on the engine and cooling system.

DPF stands for Diesel Particulate Filter, which traps soot from diesel exhaust. When it clogs, the system performs regeneration to burn the soot, increasing thermal demand and making cooling system health more critical.

Heavy-duty truck testing aims to replicate real-world stressors—towing, altitude, and extreme ambient temperatures—to validate durability of systems like cooling. The idea is that modern diesel thermal loads from emissions equipment make these tests more stringent than in the past.

Mixing coolants can be risky because different coolant chemistries may not be compatible. Incompatible mixes can form deposits, reduce corrosion protection, or upset the coolant’s freeze/boil performance. The safest approach is to use the exact coolant specification your vehicle calls for, or fully flush the system if switching types.

Glycol is the base fluid in most engine coolants, used to provide freeze protection and raise the coolant’s boiling point. In diesel engines, it’s typically mixed with water and additive packages to protect against corrosion and overheating.

Electrolysis is an electrochemical process that can occur in a coolant system when electrical potential differences exist between metals. It can accelerate corrosion by effectively “driving” metal loss, especially if coolant condition or grounding is poor.

A stray current is unwanted electrical current that finds an unintended path through the vehicle. In corrosion discussions, it can accelerate metal oxidation and contribute to pitting, especially when combined with wet environments like coolant. It’s often related to poor electrical connections or grounding issues.

When liquid coolant contacts two different metals, one can act as an anode and the other as a cathode in a galvanic corrosion cell. The anode metal corrodes preferentially, which can remove material over time. This is why mixed metals in a wet environment can cause pitting and accelerated corrosion.

Mixed metals in a coolant system can increase the risk of galvanic corrosion because different metals have different electrical potentials. When coolant provides an electrolyte path, the less noble metal corrodes faster. This is why coolant chemistry and metal compatibility matter for long-term corrosion protection.

SCA additives (Supplemental Coolant Additives) are chemicals added to coolant to provide corrosion protection, especially against liner and metal corrosion in diesel cooling systems. They help maintain the coolant’s protective film and inhibit corrosion as the coolant ages. When SCA levels drop or the coolant degrades, protection can weaken.

Mixing different coolant types (or coolant chemistries) can reduce or negate corrosion protection because additive packages may not be compatible. The additives can “fight” each other, leading to insufficient protection against the corrosion mechanisms the manufacturer designed for. This can contribute to overheating-related issues indirectly by promoting internal corrosion and restricting flow.

A check engine light (often called the MIL) comes on when the vehicle’s engine computer detects a fault in the emissions or engine management systems. It can be triggered by anything from a minor sensor issue to a more serious problem, so the key is to read the diagnostic trouble codes (DTCs) rather than guessing.

Diesel engines use compression ignition instead of spark plugs, relying on high compression and fuel injection timing to ignite the fuel. Because of that, diesel cooling systems, fuel systems, and emissions controls can behave differently than gasoline engines—important when discussing overheating, coolant leaks, and corrosion.

A cooling system additive is a chemical added to the engine’s coolant to change how the system behaves. In this case, it’s described as both corrosion protection and an overheating aid, meaning it helps prevent metal corrosion inside the cooling passages while also improving heat transfer or coolant performance.

Overheating is when the engine’s temperature rises beyond its normal operating range, usually because the cooling system can’t move or transfer heat effectively. Causes commonly include low coolant, air pockets, failing water pumps, clogged radiators/hoses, or coolant that has lost its protective properties.

Hyperloo is mentioned as a company that produced a “super coolant” product. The hosts say they bought the company in 2018 to bring that product into their own lineup, implying Hyperloo’s coolant chemistry was a key part of their strategy for cooling-system solutions.

Rizlo is mentioned as the brand the product is now “underneath.” In this context, it’s tied to a coolant offering aimed at reducing overheating issues.

The host suggests overheating risk can relate to how the cooling system’s capacity matches the vehicle’s demands. A system that’s undersized for the vehicle’s typical use may struggle to shed heat during sustained heavy loads.

This segment describes a real-world overheating scenario: towing or hauling near maximum capacity while climbing grades in high ambient temperatures. The combination increases heat generation and reduces cooling margin, even if the manufacturer says the vehicle can handle it.

Aftermarket companies build performance parts and tuning solutions that can increase power beyond factory calibration. The episode frames this as a common path for diesel owners: drive stock until warranty ends, then add turbo/tuning products that can increase heat and load on cooling and other systems.

“Turbos and tuning” refers to upgrading turbo hardware and/or reprogramming engine control to increase boost and fuel delivery. On high-output diesel builds, that can raise exhaust and combustion temperatures, which increases demand on the cooling system and can contribute to overheating or coolant-related issues.

The “Ford 6 liter” refers to Ford’s 6.0L diesel engine used in certain Super Duty trucks. In this segment, the hosts contrast it with International/Navistar’s approach and explain that Ford’s version was pushed harder for power, which increased reliability issues.

“Detuned” means the engine is calibrated to produce less power than its maximum potential. Lower output typically reduces heat and mechanical stress, which can improve durability—especially important for diesel trucks where cooling system health is critical.

“Bumped up the power stock” refers to increasing engine output from the factory calibration. When a diesel is tuned for more power without matching supporting hardware (like cooling capacity), it can run hotter and raise the likelihood of overheating and coolant-related failures.

“Power adders” and “programers” (programmers) are aftermarket ways to increase diesel engine output, often by adding performance hardware and/or changing the ECU tune. The segment implies that even before aftermarket tuning, the factory calibration already caused issues, and additional power would further stress the engine and cooling system.

Head bolts clamp the cylinder head to the engine block. If they’re not designed for the pressures/heat of the application, the clamping force can be insufficient and the head can lift under high boost.

This phrase frames the scenario as an everyday owner who changes or upgrades the product/strategy (implied tuning or coolant/maintenance approach). It’s relevant because many overheating/coolant-leak issues show up after owners increase boost or use non-standard solutions.

Temperature monitoring is how you validate whether a cooling-related change (like a fluid or additive) is actually improving heat dissipation. The key idea is that different systems and operating conditions (like RPM) can affect measured temperatures, so you need consistent comparisons. Otherwise, you may see differences that are caused by driving/engine load rather than the product.

Heat dissipation depends on engine load and speed, which is why the discussion references “at a given RPM.” At higher RPM, the engine produces more heat, so the cooling system’s ability to shed that heat can be tested more clearly. Measuring at a consistent RPM helps isolate whether a change improves cooling efficiency rather than just reflecting different operating conditions.

A thermostat is a temperature-controlled valve in a vehicle’s cooling system that regulates when coolant flows to the radiator. In normal operation, it helps the engine reach and maintain its target operating temperature, so it doesn’t “track” temperature changes linearly like a gauge would. That’s why thermostat behavior can limit how much you’ll notice from additives or fluids unless you’re monitoring precisely.

A temperature gauge (or more advanced monitoring) gives you a way to see coolant or engine temperatures in real time. Without accurate readings, it’s difficult to determine whether a fluid/additive is actually improving heat management. This is especially relevant when discussing overheating, coolant leaks, or corrosion because small temperature changes can indicate cooling system issues.

A dyno test measures engine output and behavior while the engine is run under controlled load. In this segment, they used it to compare engine temperature readings over time with and without an additive.

Temperature sensors placed in multiple locations on the engine help map how heat is generated and where it’s staying. Multiple sensor locations can reveal hotspots and show whether a cooling-related additive improves heat transfer.

Surfactants are compounds that can improve how liquids wet surfaces and move heat through a system. In coolant applications, they’re often used to enhance heat transfer and reduce hot spots by helping the coolant interact more effectively with engine and radiator surfaces.

In cold climates, coolant must resist freezing so it won’t expand and damage the engine or radiator. Freezing can crack components and cause leaks, which then leads to overheating later.

A “50-50 mix” is coolant blended at equal parts antifreeze concentrate and water. This ratio is a common baseline because it balances freeze protection, boil protection, and corrosion control.

“Dosage” here refers to the correct amount of coolant additive/product to match the cooling system’s capacity. Using too little may not provide the intended corrosion/overheating protection, while too much can upset the coolant chemistry.

A “20 quart system” indicates the cooling system capacity the product is designed to treat. Capacity matters because coolant additives are formulated to work within a specific concentration range.

The radiator cap regulates system pressure and helps raise the coolant’s boiling point. The advice to ensure the system is cool before opening is critical because pressurized hot coolant can cause severe burns.

Fuel additive products are aftermarket chemicals added to fuel with the goal of improving combustion or cleaning deposits. The hosts are drawing an analogy to coolant dosing, noting that doubling up often doesn’t produce additional benefit beyond the intended dose.

A cooling system maintenance interval is the scheduled mileage/time when you service coolant and related components to prevent overheating and corrosion. The key idea is that coolant chemistry and contamination change over time, so “when to do it” matters as much as “what to do.”

Using a vacuum to refill a cooling system helps remove air pockets and improves coolant fill quality. Air trapped in the system can reduce heat transfer and contribute to overheating, so vacuum filling is a process choice that affects performance.

An oil cooler is a heat exchanger that cools engine or transmission oil using the engine’s cooling system. If an oil cooler fails internally, oil can mix into the coolant, turning the cooling system into a contamination problem rather than just a coolant maintenance issue.

When oil enters the cooling system (commonly from a failed oil cooler), it can contaminate coolant and chemically attack materials that are only meant to see coolant. That’s why the speaker emphasizes cleaning more aggressively—residue can continue damaging the radiator, hoses, seals, and other components.

Radiator hoses are rubber coolant lines that carry coolant between the radiator and engine. Oil contamination can degrade rubber and reduce seal integrity, leading to leaks and overheating.

Seals in the cooling system (such as O-rings and gasket surfaces) are designed to be compatible with coolant chemistry. Oil contamination can swell, harden, or chemically attack seals, increasing the chance of persistent leaks after the initial failure.

The idea behind “hot flushing” a transmission cooler is to circulate fresh fluid through the cooler after a failure so metal debris and contaminants don’t keep traveling through the system. In practice, whether it’s necessary depends on what failed (e.g., internal clutch/gear damage) and how much contamination is present.

After a transmission failure, wear particles can travel with the fluid and collect in low-flow areas like the bottom of a cooler. That “settling” effect matters because flushing has to remove or dilute those deposits before the new fluid circulates.

The question being raised is whether long-term deposits from normal wear (over tens or hundreds of thousands of miles) are best handled by cleaning/flushing, or whether they’re not significant enough to justify the effort. The answer typically depends on fluid condition, cooler design, and how severe the initial failure contamination was.

A head gasket seals the engine’s cylinder head to the engine block, preventing coolant and combustion gases from mixing. If it fails, combustion gases can enter the cooling system, raising pressure and accelerating coolant breakdown and corrosion.

When combustion gases enter the cooling system (often from a failed head gasket), they change the chemistry of the coolant. That can turn coolant into an acidic environment that attacks metal surfaces and accelerates corrosion, leading to more leaks and overheating.

Power flushing is an aggressive coolant-cleaning method that uses high flow/pressure to dislodge deposits. It can be helpful in some cases, but it’s not always necessary and can sometimes stir up debris that then clogs small passages or worsens existing issues.

Cooling systems are designed to operate under pressure, which raises the coolant’s boiling point and helps prevent vapor formation. If combustion gases are present or the system is otherwise compromised, pressure can build abnormally and contribute to overheating and additional leaks.

“Power Stroke” is Ford’s diesel engine family name, commonly associated with Super Duty trucks. In this context, it’s used to ask whether the aftermarket coolant product is compatible with the OEM coolant chemistry Ford specifies for those diesel cooling systems.

“Duramax” is General Motors’ diesel engine family name, most often associated with Chevrolet and GMC heavy-duty trucks. Here it’s part of the compatibility question: whether the aftermarket coolant/additive chemistry plays well with the OEM coolant those trucks specify.

“Cummins” refers to Cummins diesel engines, most commonly found in Ram trucks (and also in other applications). The discussion is about whether an aftermarket coolant product is compatible with the OEM coolant used in those diesel trucks.

Compatibility testing is the process of verifying that an aftermarket coolant product won’t chemically conflict with OEM coolant types. In practice, it can involve mixing tests, corrosion/scale evaluation, and performance checks to ensure the additive maintains protection rather than accelerating corrosion.

“4GM” appears to be a transcription error for “GM” (General Motors), which would align with the earlier mention of Duramax (a GM diesel engine). The context is asking how the product matches OEM coolant recommendations from that manufacturer.

“Off the shelf” here means buying commercially available coolant products from retail/major brands to use in the compatibility testing program. That approach helps ensure the study reflects what customers actually mix into their cooling systems.

“Big Three OEMs” refers to the major U.S. automakers (traditionally General Motors, Ford, and Stellantis/Chrysler). OEMs often develop and specify coolant standards and service requirements, so being close to them can help a supplier anticipate new formulations and vehicle requirements.

An OEM division supplies parts and systems that get installed on vehicles during the original assembly process. The key idea is that these products are designed to meet the automaker’s specifications from day one, rather than being aftermarket replacements.

Private labeling means a company manufactures or supplies products that are sold under another company’s brand name. In automotive supply chains, this often shows up when a supplier makes components that multiple brands can market as their own.

“Heavy duty” refers to vehicles and equipment built for sustained, high-load work—like trucks, construction machines, and locomotive engines. Cooling, corrosion, and leak issues are especially important here because these systems operate under harsher conditions and longer duty cycles.

Caterpillar (Cat) is a leading manufacturer of construction and mining equipment, and it also builds diesel engines used in heavy-duty applications. In this segment, it’s cited as an example of the kinds of heavy-duty platforms the speaker’s products support.

GE here refers to General Electric’s locomotive-engine business, which has historically built diesel-electric powertrains for trains. The speaker uses it to illustrate that their heavy-duty products can be used across multiple industrial engine platforms.

A heater core is a small heat exchanger inside the HVAC system that uses engine coolant to warm the cabin. If its internal passages clog or leak, it can contribute to coolant loss and overheating-related complaints.

The speaker is emphasizing that some cooling-system passages are extremely small—on the order of fractions of a millimeter. Smaller passages are more sensitive to deposits, corrosion, and additive compatibility, which is why coolant formulation and testing matter.

ASTM is a standards organization that publishes test methods used across industries, including automotive fluids and materials. Mentioning ASTM tests signals that the evaluation follows standardized procedures so results are comparable and repeatable.

“OEM side” refers to the original equipment manufacturer perspective—how the carmaker evaluates parts and fluids for fit, durability, and warranty risk. Input from the OEM side often focuses on real-world reliability and corrosion/overheating concerns.

A remanufactured engine is rebuilt using a mix of reused and replaced components, then assembled to meet a defined quality standard. Compared with a used engine, remanufacturing typically includes more thorough inspection and replacement of worn parts, aiming to restore reliability.

An “industry leading warranty” is a marketing and risk-reduction claim that indicates the seller backs the remanufactured engine with a longer or more comprehensive warranty than typical. For buyers, warranty terms can matter as much as the parts quality because they affect what happens if something fails.

An OEM engine is a factory-spec engine design—built to the original equipment manufacturer’s specifications. In remanufacturing discussions, “basic OEM engine” implies a stock-like rebuild rather than an upgraded configuration aimed at preventing repeat failures.

“Speed of air series” appears to refer to a specific diesel engine technology/product line that the hosts say they’ve covered before. The key idea is that it’s designed to improve combustion efficiency and overall engine performance compared with a more conventional setup.