Overheating, Coolant Leaks & Corrosion
The Diesel Podcast
Overheating, Coolant Leaks & Corrosion The Diesel Podcast · Apr 17, 2026
Overheating, Coolant Leaks & Corrosion

Annotations will appear as you listen

0:00
59:12
Overheating, Coolant Leaks & Corrosion
Company

DFC Diesel

DFC Diesel is the company behind the podcast intro. It usually means the show is connected to diesel parts and shop experience.

Concept

regulatory and emissions

Emissions rules can change how diesel engines are built and tuned. Those changes can also affect how the truck runs and what problems show up, including temperature and cooling-related issues.

Term

start-stop technology

Start-stop technology turns the engine off when you’re stopped (like at a light) and turns it back on when you start moving again. It helps save fuel, but it can also affect how hard the engine and related systems work day to day.

Concept

regulatory side

The regulatory side is basically the government rules about emissions and what cars are required to do. Car makers plan years ahead, so when rules change, it can be hard to know what will be required by the time a vehicle is ready.

Term

GPF filters

A GPF is a filter on gasoline cars that catches soot from the exhaust. It’s mainly there to meet emissions rules, so if regulations change, the need for it can change too.

Company

Rizz loan

Rizz loan is an additives brand the hosts are talking about. In this conversation, they’re explaining how its products relate to leak-stopping additives like Bars Leaks.

Company

Bars leaks

Bars Leaks makes products you pour into a car’s cooling system to help stop small leaks. It works by putting a sealing material into the leak area while the coolant circulates.

Company

Kershaw Knives

Kershaw Knives is a knife brand sponsoring the podcast. It’s an ad read rather than a vehicle-related technical discussion.

Lincoln Nautilus
Car

Lincoln Nautilus

The Lincoln Nautilus is a luxury SUV, meaning it’s designed to be comfortable and practical for everyday driving. It’s made by Lincoln, and it typically costs more than regular non-luxury SUVs. The podcast may mention it because the name “Nautilus” is also used in other contexts.

Concept

USS Nautilus

The USS Nautilus is a famous historical ship. The host is just saying they like that kind of history, not discussing car technology here.

Company

BarzLeaks

BarzLeaks is a leak-sealing product you add to a system. The idea is that it flows to the leak, then hardens or forms a seal so the leak stops. It’s often used as a “stop the leak” approach.

Term

condenser

A condenser is a heat-exchange component where a hot fluid releases heat to another medium. In the transcript, the condenser is described as having a leak, which matters because leaks in heat exchangers can quickly reduce cooling effectiveness and lead to overheating.

Concept

stop-leak / sealing a leak

This is the idea of using a sealant to plug a leak from the inside. It can work for small leaks, but it doesn’t fix the real problem that caused the leak in the first place.

Term

DF fluid

“DF fluid” is a special fluid used in diesel systems to help them work properly. If it gets too cold, it can crystallize, which means the system can’t use it the way it’s supposed to. When that happens, the truck may warn you or limit operation until the fluid is corrected.

Concept

crystallize

Crystallize means the fluid turns into crystals instead of staying liquid. If that happens, the truck can’t move the fluid through the system the way it needs to. Keeping the fluid warm enough and using the right product helps prevent this.

Term

cooling systems

Your engine makes a lot of heat, and the cooling system is what keeps it from getting too hot. Coolant circulates through the engine and radiator to carry heat away. If you don’t pay attention to it, the truck can overheat and cause expensive damage.

Term

coolant

Coolant is the liquid that helps your engine stay at the right temperature. It carries heat away so the engine doesn’t overheat. If coolant gets old or contaminated, it can stop protecting the engine and cooling parts.

Term

DIYers

DIYers refers to people who do maintenance themselves rather than using a shop. The segment highlights that modern cooling-system designs can be more difficult to access, which increases the chance of deferred maintenance. That can lead to overheating-related problems over time.

Term

corrosion

Corrosion is rust-like damage that can happen inside the cooling system. If the coolant isn’t fresh or isn’t the right type, it can stop protecting the metal parts. Over time, that damage can cause blockages and leaks.

Term

regeneration

Diesel trucks sometimes have to “clean themselves” by burning off soot. That cleaning process gets very hot, so the engine and cooling system have to work harder.

Term

DPFs

A DPF is a filter that catches soot from diesel exhaust. When it fills up, the truck burns the soot off, which creates extra heat and can stress the cooling system.

Concept

heavy-duty truck testing

When engineers test trucks, they try to recreate tough real-life conditions. The goal is to see how well the truck’s cooling and other systems survive when it’s hot, climbing hills, or towing.

Concept

can they be mixed

You generally shouldn’t just mix random coolant types. Some coolants don’t play well together and can cause sludge or less protection against rust. If you need to change coolant, it’s best to follow the vehicle’s recommended type or do a proper flush.

Term

glycol

Glycol is the main liquid inside your radiator/cooling system. It helps keep the engine from freezing in cold weather and from boiling over when things get hot.

Term

electrolysis

Electrolysis is a kind of chemical/electrical reaction. In a cooling system, it can make corrosion happen faster because different metal parts and the coolant can create an electrical effect that eats away at the metal.

Concept

stray current

Stray current is electricity that’s going somewhere it shouldn’t. When it flows through metal parts in the presence of coolant, it can speed up rust and pitting. Fixing the electrical connection/grounding can help stop the problem.

Concept

anode and cathode

If two different metals sit in coolant together, they can act like a battery. One metal gets “sacrificed” and corrodes faster, which can create small pits. Using the right coolant and keeping metal contact/compatibility correct helps prevent it.

Concept

pitting

Pitting is localized corrosion where small holes or craters form on the metal surface. It’s a common outcome of galvanic corrosion and other corrosion processes in coolant systems. Pitting can weaken components and lead to leaks even if the overall surface doesn’t look badly corroded.

Concept

mixed metals

Mixed metals can rust faster when they’re both exposed to coolant. Coolant acts like a conductor, so one metal can corrode quicker than the other. Keeping the system’s materials and coolant correct helps prevent that.

Concept

SCA additives

SCA additives are chemicals mixed into coolant to help prevent rust and corrosion. Over time, the coolant can lose its protective power. If the additives break down, the cooling system can start corroding internally.

Concept

mix too many different types

Mixing different coolants can make the protection weaker. The chemicals meant to stop corrosion may not work well together. That can let rust build up inside the cooling system.

Term

check engine lights

That “check engine” light means the car’s computer noticed something wrong. It doesn’t always mean the engine is about to fail, but you should scan it for codes so you know what the problem actually is.

Term

diesel engines

Diesel engines work differently than gas engines: they don’t use spark plugs to ignite the fuel. That difference can affect how the engine runs and what kinds of problems show up, especially around cooling and maintenance.

Concept

cooling system additive

Coolant additives are liquids you mix into your engine coolant. They can help stop rust/corrosion inside the cooling system and can also help the engine run cooler if the coolant isn’t doing its job as well.

Concept

overheating

Overheating happens when the engine gets too hot because the cooling system isn’t working well. It can be caused by low coolant, blocked passages, or coolant that’s no longer protecting the system.

Company

Hyperloo

Hyperloo is the company they say they bought. They’re describing it as the source of a coolant product they wanted to add to their own offerings.

Company

Rizlo

They’re talking about a coolant brand called Rizlo. The point is that the coolant is marketed to help prevent engine overheating problems.

Concept

size of the cooling system compared to the vehicle

They’re saying some vehicles have cooling systems that aren’t quite big enough for how hard they’re used. If you push the truck a lot, the engine can get hotter than the system can handle.

Concept

maximum load hauling up hills in hot weather

They’re describing a tough driving situation: hauling near your truck’s limit and climbing hills in very hot weather. That’s when the engine can run hotter because it’s working harder and the air isn’t helping cool it down.

Concept

aftermarket companies

Aftermarket companies make upgrades for your truck, like performance tuning or turbo-related parts. The hosts are warning that these changes can create extra heat and stress compared to the factory setup.

Term

turbos and tuning

“Turbos and tuning” means adding or changing turbo boost and adjusting the computer settings to make more power. More power usually means more heat, so the cooling system has to work harder.

Ford 6 liter
Car

Ford 6 liter

They’re talking about a Ford diesel engine that’s about 6.0 liters. The point is that Ford made more power from it than some other versions, and that extra stress can lead to more problems—especially when the cooling system can’t keep up.

Company

International Navistar

International Navistar is the company behind Navistar’s diesel engine family used in some trucks. Here, the hosts say Navistar’s version was “detuned,” meaning it was tuned for less output, which they claim helped it avoid many problems compared with the Ford-tuned version.

Concept

detuned

Detuned just means the engine is programmed to make less power. Making less power usually runs it easier, which can help prevent overheating and other stress-related issues.

Concept

bumped up the power stock

They mean the engine was made to produce more power right from the factory. More power can create more heat, and if the cooling system isn’t up to it, you can end up with overheating or coolant problems.

Term

power adders programers

These are aftermarket tools that try to make the diesel produce more power. More power usually means more heat and stress, so if the truck already runs hot or has coolant issues, tuning can make it worse.

Concept

head lifting off the block under boost

When a boosted engine makes more cylinder pressure than the clamping system can handle, the cylinder head can lift slightly off the block. That can lead to combustion gases escaping, coolant leaks, overheating, and ultimately head gasket failure.

Term

head bolts

The head bolts hold the top of the engine (the cylinder head) tight to the engine block. If they aren’t strong enough for the boost/pressure, the head can start to lift and cause leaks or overheating.

Term

head studs

Head studs are upgraded fasteners used to clamp the cylinder head more reliably than factory bolts, especially on high-boost or tuned engines. They help maintain clamping force and reduce the risk of head gasket failure from head lift.

Term

regular truck owner

The speaker is talking about a normal truck owner, not a race team. The takeaway is that common ownership choices—like changing how the truck is set up—can affect overheating and leak problems.

Concept

monitoring temperatures

Monitoring temperatures means checking engine or coolant temps while you drive or run the engine. It helps you figure out if something you added or changed is truly helping cooling. But you have to compare fairly, like using similar RPM/load, or you might misread the results.

Concept

heat dissipation at a given RPM

Engines make more heat when they spin faster and work harder. That’s why comparing cooling at the same RPM is a fair test. If temperatures drop at the same RPM after a change, it’s more likely the change is actually helping.

Concept

using fluid or additive to improve cooling performance

The hosts discuss a common question: whether running a specific fluid or additive will measurably improve cooling performance. The important nuance is that some products may only show benefits under certain conditions (like existing cooling system issues), and without proper temperature monitoring you can’t easily prove the effect. This ties directly into overheating and coolant-leak diagnostics—sometimes the “fix” is addressing the underlying problem rather than adding something.

Term

thermostat

The thermostat is like a temperature gate for your engine coolant. It stays closed until the engine warms up, then it opens to let coolant circulate. If you don’t have a way to measure temps accurately, it’s hard to tell whether anything is improving cooling.

Term

gauge

A gauge is a tool that shows you what the engine temperature is doing. If you don’t have one, you’re basically guessing whether your cooling system is working better. With a gauge, you can compare temperatures before and after changes.

Concept

dyno test

A dyno is a machine that lets you run the engine while it’s controlled and measured. Here, they used it to see how engine temperatures changed when they added a product versus not adding it.

Term

temperature sensors

Temperature sensors are small probes that measure how hot different parts of the engine get. Using several of them helps you see whether the engine is running hotter in certain spots.

Concept

surfactants

Surfactants are chemicals that help a liquid spread and work better across surfaces. In a cooling system, that can mean the coolant transfers heat more efficiently so the engine doesn’t get as hot.

Concept

freezing over

When it gets very cold, coolant has to stay liquid. If it freezes, it can crack parts and cause leaks.

Term

50-50 mixes

A 50-50 mix means you combine coolant concentrate and water in equal amounts. It’s a common recipe that helps the engine stay protected in both hot and cold weather.

Term

dosage

Dosage just means using the right amount of the product for your engine’s cooling system size. Getting it wrong can mean it won’t work as intended or could cause problems.

Term

20 quart system

This means the product is meant for a cooling system that holds about 20 quarts of coolant. Using it on a system with a very different capacity can make the additive too weak or too strong.

Term

radiator cap

The radiator cap is what keeps pressure in the cooling system. You should only open it when the engine is cool because hot pressurized coolant can spray out and burn you.

Term

fuel additive products

Fuel additives are chemicals you add to gas or diesel. The point here is that using more than the recommended amount usually doesn’t help much and can be a waste.

Concept

cooling system maintenance interval

Coolant doesn’t last forever. A cooling system maintenance interval is the recommended schedule for refreshing coolant so your engine stays cool and doesn’t rust inside the system.

Concept

cooling system under a vacuum

A vacuum fill helps pull air out of the cooling system while adding coolant. That matters because trapped air can cause hot spots and overheating.

Part

oil cooler

An oil cooler helps keep oil from getting too hot. If it fails, oil can leak into the coolant and cause overheating and damage because the coolant system wasn’t meant to handle oil.

Concept

oil contamination attacking cooling system components

If oil gets into your coolant, it can act like the wrong chemical for the cooling system parts. Even if you replace coolant, leftover oil residue can still cause damage and leaks.

Term

radiator hoses

Radiator hoses are the tubes that move coolant around the engine. If oil gets into the coolant, it can harm the rubber and make hoses leak.

Term

seals

Seals are the rubber or gasket parts that keep coolant from leaking. If oil gets mixed into the coolant, it can damage those seals and cause leaks to keep coming back.

Concept

hot flush the transmission cooler

After a transmission problem, tiny metal bits can get stuck in the cooler. Flushing it helps push that dirty fluid out so the new transmission fluid doesn’t immediately carry debris back into the system.

Concept

metal and debris settling in the cooler

When a transmission breaks, small metal bits can get carried by the fluid. Some of those bits can collect in the cooler, and then they can keep causing problems unless you clean them out.

Concept

deposits/contamination after high mileage

They’re asking whether old buildup inside the cooler is worth cleaning out. Sometimes it’s just normal wear, and sometimes it’s heavy contamination that can shorten the life of new parts.

Part

head gasket

The head gasket is a seal between the engine block and the cylinder head. If it goes bad, exhaust gases can leak into the coolant, which can quickly damage the cooling system and lead to overheating.

Concept

combustion gases into the cooling system

Normally, exhaust gases stay in the engine. If they get into the coolant, they can make the coolant chemically harmful, which can rust and damage parts inside the cooling system.

Concept

power flushing

Power flushing is like a more forceful coolant cleaning. It’s not always needed, and if your system already has problems, the extra agitation can sometimes make things worse.

Concept

pressure in there

Your cooling system runs pressurized so the coolant boils at a higher temperature. If something is wrong—like exhaust gases getting in—pressure can rise too much and cause overheating and leaks.

Power Stroke
Car

Power Stroke

“Power Stroke” is the name Ford uses for many of its diesel engines. They’re bringing it up because different trucks may use different coolant formulas, and you want to make sure the product you add won’t react badly.

Duramax
Car

Duramax

“Duramax” is GM’s diesel engine name. They’re asking if the coolant product you add is compatible with the coolant your truck already uses.

Cummins
Car

Cummins

“Cummins” is the name of a diesel engine used in many trucks. They’re asking if the coolant product works safely with the coolant those trucks are designed to use.

Concept

compatibility testing

Compatibility testing means checking that a coolant product is safe to mix with the coolant your truck already uses. The goal is to prevent corrosion and other cooling-system problems.

Brand

4GM

This looks like a misheard “GM.” They’re basically asking whether the coolant product works with the factory coolant recommendations from major truck makers.

Concept

off the shelf

“Off the shelf” means they buy regular coolant products that regular people can buy. That way their testing matches real-world mixing situations.

Brand

big three OEMs

“Big Three OEMs” means the biggest car manufacturers in the U.S. When a supplier stays connected to them, they can learn about new coolant requirements earlier and test products to match what new vehicles need.

Concept

OEM division

OEM means “original equipment manufacturer.” An OEM division makes parts that go into the vehicle when it’s being built, not parts you buy later to fix or upgrade it.

Concept

private label

Private label is when one company makes a product, but another company sells it under their own name. It’s common in parts and industrial supplies.

Concept

heavy duty side

“Heavy duty” means machines that are built to work hard for long periods, like trucks and construction equipment. Cooling and leak problems matter a lot because these machines run in tough conditions.

Company

Caterpillar

Caterpillar is the company behind a lot of the big machines you see on construction sites. They also use diesel power in heavy equipment, so it’s a good example of the “heavy-duty” world.

Company

Kamatsu

Komatsu (often misspelled as “Kamatsu” in transcripts) is a major manufacturer of construction equipment and diesel-powered machinery. Mentioning Komatsu reinforces that the conversation is about industrial/heavy-duty engine and equipment ecosystems.

Company

GE

GE is a big industrial company, and in this context it’s tied to train locomotive engines. It’s mentioned to show the discussion includes diesel power used in transportation and industry.

Part

heater core

A heater core is like a tiny radiator that sits inside the dashboard. Hot engine coolant flows through it to make warm air for the cabin—if it leaks, you can lose coolant.

Term

millimeters

They’re pointing out that some internal channels are tiny. Tiny passages can clog more easily if the coolant isn’t right.

Company

ASTM tests

ASTM tests are standardized lab tests. They’re used to make sure results are consistent and meaningful.

Concept

OEM side

“OEM side” means the carmaker’s point of view. They care about whether the product will work reliably in the vehicle over time.

Concept

remanufactured engines

A remanufactured engine is a used engine that gets taken apart, inspected, and rebuilt with new or good replacement parts. The goal is for it to run like it should, not like an unknown used motor.

Concept

ISO 9001 2015 standards

ISO 9001 is a quality-management standard that focuses on consistent processes—how a company builds, tests, and controls products. When an aftermarket remanufacturer says it meets ISO 9001:2015, it’s signaling disciplined manufacturing and documentation, not just “good luck” quality.

Concept

quality testing validation

“Testing validation” refers to the verification steps used to confirm components and finished engines meet required performance and durability expectations. In an aftermarket reman context, this helps reduce the risk of repeat failures by ensuring the engine is checked before it’s shipped.

Term

industry leading warranty

A warranty is the promise that if the engine has problems, the company will cover repairs or replacement. “Industry leading” usually means the coverage is better than average.

Concept

OEM engine

OEM means “factory original.” A basic OEM engine rebuild is meant to match how the engine was originally built, not necessarily to fix weaknesses that caused earlier problems.

Concept

speed of air series

They mention a “speed of air” engine series. The gist is that it’s a special diesel setup meant to make the engine burn fuel more efficiently, which can help power and fuel economy.

0:00
59:12