8 Different Ways A Car Wash Could Damage Your Car’s Engine – And How To Avoid These Damages

Keeping a car clean is the least we could do, given how much money they cost us.

However, despite the will to keep a car clean, many people neglect washing the engine due to its intricacies.

Engine cleaning is typically left to the professionals to avoid damaging it, but how much harm can a car wash do to your engine? 

Quick Answer

An engine isn’t waterproof and can incur severe damage in a car wash if washed incorrectly. Coldwater on a hot engine block can cause it to warp, exposing wires and sensors can lead to their malfunctioning, and a wet intake system can cause far more severe damage. 

Read on as we take a deeper dive into how washing your engine can cause it to suffer damage.

We will also discuss the proper way to clean your engine, aside from the benefits that come with keeping it spotless. 

Can a Car Wash Damage Your Engine?

As much as we want to pamper our car with a good engine wash, water and engines don’t exactly make a great combination.  

Quick Answer

A car wash can damage your engine since many engine components are sensitive to water. Exposing these parts to water can cause them to stop working. Modern automobiles sport better-insulated engine parts, making them less vulnerable to water damage. However, such parts are not 100% water-proof.

It pays to know which parts are the most susceptible to damage and how they can affect your car’s performance. 

How Water Can Damage the Engine’s Cylinder Head

Adding water to a hot engine is a recipe for disaster. Metal parts like your car’s cylinder head can experience thermal shock due to a sudden shift in temperature.

This reaction causes tension within the metals and could cause them to warp, crack or break. 

A cylinder head is essentially the engine’s armored suit; it keeps all the internal components and fluids in place.

If a cylinder head is damaged, any of the following may occur: 

  • Engine oil may start to leak. A cracked cylinder head can cause engine oil to seep out of the engine. If enough oil leaks out, it can severely compromise how well lubricated the engine is, causing even more significant damage. 
  • The engine may start leaking coolant. A drop in coolant level can affect the engine’s temperature, causing the engine to overheat. The coolant can also contaminate the engine oil if the cylinder head is damaged. 
  • A damaged cylinder head can cause the engine to start misfiring in more severe cases. Think of the cylinder head like a house where all the car’s cylinders live. If the home is severely damaged, it will affect how the cylinders do their job and eventually cripple the entire engine. 

How Water Can Damage Your Car’s Electrical System

Cars now have more electrical systems than ever, many of which reside under the hood.

For these electrical systems to be functional, car manufacturers can only make them water-tight to a certain extent. 

Many plumbing materials use copper, and according to a study done by ScienceDirect, the amount of copper in water affects its corrosion rate. 

Quick Answer

Generally speaking, water and electricity do not mix because this can cause premature corrosion, aside from a short circuit. Due to water contamination, parts like the fuse box, onboard computer, and other electrical modules may experience electrical shorts. 

Removing the car’s battery can prevent short circuits, but that doesn’t safeguard all the car’s electrical components from damage.

Below are other electrical components under the hood that can be compromised by exposure to water: 

  • The car battery. A car’s battery can withstand some degree of water exposure, but moisture on the terminals can cause corrosion. Corroded terminals can compromise the connection between your vehicle and the battery, which will affect how well the battery charges. 
  • The alternator. Like car batteries, alternators can get wet, but they are not immune to water. Since alternators are air-cooled, they have airways where water can pass, and prolonged or frequent water exposure can cause their internal components to rust. Trapped water can also lead to grime, affecting the alternator’s performance. 
  • The distributor caps. Suppose water manages to make its way inside a distributor cap. It can disturb the flow of electricity to the sparkplugs, leading to misfiring or difficulty getting the engine to start. 

The Effects of Water on Your Car’s Intake System

A car’s intake system is composed of an air filter, mass flow sensor, and throttle body.

It is responsible for sucking in air to be mixed with fuel and compressed as part of the combustion process. 

If a substantial amount of water manages to make its way to your car’s intake system, the water will not be compressed and will result in a pressure build-up that can bend your piston rods and crack your engine block. 

Is Washing Your Car Engine Bad?

Quick Answer

Washing your car engine can be risky but only if you don’t take proper care when doing so. All things considered, it is far more advantageous to clean your car’s engine on a regular basis instead of leaving it dirty. 

Keeping your car’s engine clean has the following benefits: 

  • It increases your engine’s longevity. A dirty engine can harbor corrosive elements that can harm it, especially when they accumulate. 
  • It keeps your engine running optimally. The build-up of debris in an engine can block inlets, outlets, and other passageways that compromise its performance. 
  • It is easier to detect leaks when the engine is kept clean. Faulty or worn-out gaskets and seals can cause leaks which will be hard to see if there is plenty of caked-on grime on the engine. 
  • It looks so much better. While this benefit is merely cosmetic, there’s no denying that a clean engine is more pleasing to look at. 

What To Do if a Carwash Has Damaged Your Engine

After having your car cleaned at a carwash, it is always a good idea to inspect it for any damage.

However, water damage to your engine may not always be visible, so you should let the car run idle for a few minutes before leaving the establishment. 

Aside from giving your engine bay a visual inspection to check for any physical damage, do the following: 

  • Pay attention to any irregularities in how the engine sounds. 
  • Check for any peculiar smells, as any electrical shortages, or other forms of damage, can be detected by your olfactory senses. 
  • If you notice anything out of the ordinary, immediately inform car wash personnel and switch the vehicle off -keeping it running may worsen any issues. 
  • Ensure that all water-sensitive parts are dry by requesting the staff give it another pass with a blow dryer. 
  • Don’t forget to check accessible internal components such as the air filter and spark plugs. 
  • After any potentially water-contaminated areas have dried, start the car up again and check if that has resolved the issue. 

If the car still fails to run normally, take the following action: 

  • Inform the person in charge. Ask to speak to the owner or manager of the establishment to see what assistance they can offer. It is in the owner’s best interest to ensure you leave their establishment as a happy camper. 
  • Make sure the incident is documented correctly. Request an incident report that acknowledges the issues and the fact that they only became apparent after the carwash. Ensure that the owner or an authorized representative of the carwash signs the document. 
  • Inform your insurance company. You can also get in touch with your insurance company, which should give you additional guidance and assist with any potential claims. 
  • Seek legal advice. As a customer, you have the legal right to have your car washed without accepting any damages inflicted upon it. 

Note that in case your car suffers damage, you will need to establish that the damage was done intentionally or through the carwash establishment’s negligence.

Legal fees can cost more than the actual damage in most cases, so it is best to settle claims through insurance. 

Key Takeaways

Although engines in modern cars are better insulated, you can’t discount the risk of them incurring water damage.

The good news is, as long as whoever is washing it takes proper caution, the chances of any damage are very minimal.

In fact, keeping an engine dirty is far more detrimental than washing it now and then. Thus:

  • A carwash can damage your car’s engine if done improperly. 
  • There are more benefits to keeping your engine clean instead of leaving it dirty. 
  • If your engine is damaged at a carwash, exhaust all efforts to settle a claim without taking legal action. 


Fix Auto USA: Do Car Engines Need to Be Cleaned?

Car and Driver: How to Clean Your Car’s Engine

Kenny’s Auto Detail: Benefits of Engine Steam Cleaning.

South Florida Sun Sentinel: Driving through puddles can kill your car

VEHQ: Can You Wash An Engine While It’s Hot?

Corrosionpedia: Thermal Shock

Clearwater Cylinder Head, Inc.: How to Tell if Your Cylinder Head is Bad

It Still Runs: What Happens With Water Damage in a Car?

Burley Electrical Services, Inc.: Why Does Water Cause a Short Circuit, Fry & Ruin Electronics in Plantation, FL?

Protect My Car: Can Water Damage Your Car’s Alternator?.

Answers To All: What happens when distributor cap gets wet?

ScienceDirect: Corrosion Science: The corrosion behaviour of copper in neutral tap water. Part I: Corrosion mechanisms

sgCarMart: Understanding a car air intake system

Hensley Legal Group: Who is Liable if My Car is Damaged at a Car Wash?

WashTec: Damage to a vehicle caused by a car wash – But who is liable?



Jan-Lucas Ganssauge
Jan-Lucas Ganssauge