Can You Use Brake Cleaner as Starter Fluid? Full Guide with Pros, Cons, and Safety Tips

Can you use brake cleaner as starter fluid? Yes, but it’s unsafe and not recommended due to engine damage and toxic fumes.

When your car won’t start and you’re stuck with no starting fluid on hand, you might look around your garage and spot that can of brake cleaner. It’s flammable, after all—so the question arises: can you use brake cleaner as starter fluid?

This is a surprisingly common question among DIYers, backyard mechanics, and even off-road enthusiasts in a pinch. While brake cleaner can, in some cases, get an engine to turn over, it’s not designed for this purpose and can carry serious risks to both the engine and the health.

What Is Starting Fluid?

Starting fluid is a volatile, highly flammable compound used to help internal combustion engines start, especially in cold weather or when the engine is having trouble firing.

Key Characteristics:

Contains ether, a substance that vaporizes and ignites easily.
Designed to burn cleanly and safely inside an engine.

Typically comes in aerosol form and is sprayed into the intake or air filter.

It’s commonly used in:

Cold-weather engine starts (especially diesels)

Diagnosing fuel delivery or ignition issues
Emergency starts

What Is Brake Cleaner?

Brake cleaner is a solvent, not a fuel. It’s designed to clean metal components of oils, grease, and brake dust. It evaporates quickly and leaves no residue, making it ideal for cleaning brake rotors, calipers, and clutch parts.

There are two types:

Chlorinated Brake Cleaner – Contains tetrachloroethylene and other chlorine-based solvents. Non-flammable, but highly toxic when burned.
Non-Chlorinated Brake Cleaner – Made with hydrocarbons like acetone and heptane. These are flammable, which is why people sometimes use them as a makeshift starting fluid.

So, Can You Use Brake Cleaner as Starter Fluid?

Short answer: You can, but you really shouldn’t unless you fully understand the risks.

Chemical Differences Between Brake Cleaner and Starting Fluid

Property	Starting Fluid	Brake Cleaner (Non-Chlorinated)
Primary use	Starting engines	Cleaning brake parts
Volatility	Very high (ether-based)	High (hydrocarbon-based)
Flammability	Yes	Yes (non-chlorinated only)
Lubrication	Some formulations include oil	None
Designed for combustion	Yes	No
Safe for oxygen sensors	Yes	No (can foul sensors)

Risks of Using Brake Cleaner as Starting Fluid

Here are the main risks of using brake cleaner as starting fluid:

1. Engine Damage

Brake cleaner does not contain lubricants. Starting fluid sometimes contains light oil to prevent dry starts, but brake cleaner does nothing to protect the pistons, rings, or valves. Dry combustion can cause scuffing or premature wear.

2. Toxic Fumes

Especially with chlorinated brake cleaner, combustion can produce phosgene gas, a toxic compound used as a chemical weapon in WWI. Even non-chlorinated types can emit harmful hydrocarbons when burned. Read more about Chlorinated vs Non-Chlorinated Brake Cleaner.

3. Fire Hazard

Brake cleaner vapors are highly flammable in enclosed areas. Using it near spark plugs, open flames, or even hot engine parts can lead to unexpected ignition or explosions.

4. Sensor Contamination

Modern engines use oxygen sensors, catalytic converters, and MAF sensors. Brake cleaner isn’t designed to combust cleanly, and residue can foul these sensors, leading to expensive repairs.

5. Uncontrolled Combustion

Starting fluid is engineered for smooth ignition. Brake cleaner may combust too quickly, leading to backfires, pinging, or even engine knock.

Situations Where People Might Use Brake Cleaner (But Shouldn’t)

Here are some situations where people might use brake cleaner (but shouldn’t) as a starting fluid:

Stranded without starting fluid

Testing if an engine will run
DIY troubleshooting in old carbureted engines
Trying to diagnose fuel pump issues

Yes, it can work—but at what cost?

A YouTube search will show dozens of people spraying brake cleaner into a throttle body and cranking the engine. Some engines do start—but without understanding the long-term damage, this can be a costly shortcut.

Safe Alternatives to Starting Fluid

If you’re out of starting fluid, here are safer options:

1. Carburetor Cleaner

Like starting fluid, brake cleaner is flammable and can help start older engines. It still lacks lubrication, but it’s generally less toxic than brake cleaner.

2. WD-40

An old-school trick, WD-40 in aerosol form is flammable and can be used to prime an engine safely in some cases. Modern versions may be less flammable due to VOC regulations.

3. Gasoline-Soaked Rag

In very small amounts, placing a gasoline-soaked rag near the intake can assist starting—but this is extremely dangerous and should only be attempted by experienced individuals.

When Is It Safe to Use Starting Aids at All?

Only on well-maintained engines
As a diagnostic tool, not a fix
Never as a regular starting procedure

When the manufacturer allows it (some diesel engines permit ether)

How to Diagnose a Hard Start the Right Way

Instead of relying on any spray, try this process:

Check for Spark Use a spark tester or pull a plug and ground it to see if there’s spark.

Check Fuel Delivery Can you hear the fuel pump prime? Pull the fuel line (safely!) to check for flow.
Test Compression An engine that cranks but won’t fire might have low compression. Time to break out the compression tester.
Scan for Codes On OBD2 vehicles, plug in a scan tool and see if you’re dealing with crank sensor failure, MAF issues, or injector faults.

Real-World Example

A user on a popular car forum posted:

“My 1998 Honda wouldn’t start, and I didn’t have starting fluid. A friend sprayed non-chlorinated brake cleaner into the intake, and it actually fired up—but ran rough. Later, I had to replace my O2 sensors. Coincidence? Probably not.”

This isn’t a one-off. Mechanics often caution against using brake cleaner this way because short-term success often comes with long-term consequences.

Frequently Asked Questions

Here are some FAQs about using brake cleaner as starter fluid –

1. What happens if I use brake cleaner to start my engine?

Your engine might start, but you risk damaging internal components, contaminating sensors, and inhaling toxic fumes.

2. Is carburetor cleaner safer than brake cleaner for starting?

Yes. Carb cleaner is flammable and less toxic than brake cleaner when combusted. Still, use it sparingly.

3. Can using brake cleaner void my warranty?

Absolutely. Using any product outside of its intended use can void your vehicle warranty and even lead to insurance issues if it causes damage.

4. Will using brake cleaner harm my catalytic converter?

Yes. The residue and combustion byproducts can coat the catalyst, reducing its efficiency and causing a check engine light.

5. What should I do if I used brake cleaner and now the engine runs rough?

Check for fouled sensors (O2 and MAF), inspect plugs, and scan for trouble codes. You may need to replace damaged components.

Conclusion

So, back to our main question: can you use brake cleaner as starter fluid?

Yes, technically. But no, you really shouldn’t.

Brake cleaner—especially the non-chlorinated type—is flammable and can ignite inside an engine, but it:

Isn’t formulated for combustion
Can damage sensors and engine internals

Produces harmful or toxic fumes
Carries major fire risks

Always try to keep a can of actual starting fluid in your garage or trunk if you often work on engines. It’s cheap insurance and far safer.