Can Water Damage Your Car’s Alternator?


Your alternator is very well protected from things like rain and driving through deep puddles but sitting in deep water has the potential to damage your alternator if it is not dried out quickly.

With that in mind, let’s take a deep dive (pun intended) into the ins and outs of how water works with your alternator.

What Is Your Car’s Alternator?

If you think about it, your car needs a lot of electricity. Most of us take for granted our headlights, dash lights, charging ports, and the like, not to mention the engine starting. While it’s easy to assume the battery is providing this power and be done with it, that’s not entirely the truth.

While car batteries can have an enormous capacity compared to your iPhone, they need to be charged too, which is what the alternator does. Your alternator translates mechanical energy into the potential energy that’s stored in your battery by a spinning pully. This energy makes sure your battery is always full and always has the energy to start your car, and run your nav, heater, stereo and the like.

Considering your alternator is basically your car’s generator, you can imagine that you probably don’t want it to get wet.

However, your alternator does fine against water (in most cases).

Is Your Car Alternator Waterproof?

Car alternators are NOT waterproof. Considering how the alternator is built to function, it is almost impossible to waterproof it. Most alternators are air-cooled, with air being drawn through the alternator by an internal fan which is attached to the drive end of the alternator shaft.

Cool air is sucked in through the non-drive end while hot air is expelled through the drive end.

But just because your alternator isn’t waterproof, that doesn’t mean it’s not water resistant.

For example, Stamford Alternators which are used in generators have an IP rating of 23 with an optional upgrade to IP44.

The IP code (or IP rating) is a number between 11 and 68.  The first digit (from 1-6) describes the degree of protection against solid objects, especially dust.

The second digit which can be between 1 and 8 tells us the protection against water.

To be considered “waterproof” an enclosure needs to be rated between an IP 65 and an IP 68.

Now that we understand IP ratings a little bit better let’s talk about what that actually means for your alternator.

In this case, a IP23 rating translates to:

  • 2: Protected against a solid object greater than 12.5mm which is roughly the size of your finger.
  • 3: Protected against sprays of water up to 60 degrees from vertical. Can handle limited amounts of water for up to 3 minutes.

Which makes sense because…

Your Alternator Is Designed To Handle Water

With many cars, your alternator is regularly exposed to water in the engine bay. That includes water from rain, from puddles, and from washing the engine bay directly.

Your engine bay isn’t sealed. Water gets splashed on it all the time.

In over 20 years of working as a mechanic I’ve yet to see an alternator destroyed by normal driving, including through deep puddles.

With that being said, splashing water isn’t the problem. It’s sitting water.

But Bad Things Happen When You Flood It

If you submerge the alternator, it will work. The electrical components of your alternator are sealed. The problem is what isn’t.

The brass or bronze brushes within your alternator are lubricated to keep the wear and electrical arcing down. When they get wet, this lubrication wears away. The brushes then get damaged by the electrical arc and wear out.

Repeated exposure to water can also cause these brushes to rust which can cause them to come out of contact with the slip rings.

The other issue you’ll run into with a flooded alternator is grime. If your car is submerged in water, things like sand and dirt can get into the brushes and freeze them out of contact with your slip rings.

Granted, if your car is sitting in flood water you probably have other concerns.

Now let’s move into some questions.

Can You Clean an Alternator With Water?

You certainly can clean your alternator with water if you don’t pressure wash it directly. Pressure washing your engine bay can cause damage to your seals and we don’t want that as we’ll talk about in a second, that’s not what you want to do.

Water is recommended over petroleum-based engine degreasers when it comes to cleaning your alternator.

So here’s what you do:

  1. Disconnect the battery so you don’t shock yourself.
  2. Get a bucket with warm water and a bit of dish soap like dawn. Mix a little bit into the water.
  3. Gently pour/spray the water and soap mix on the alternator terminals and brushes.
  4. Let the soap work its magic for 5 minutes.
  5. Gently scrub the dirty areas with a wire brush.
  6. Rinse thoroughly with clean water and allow the alternator to dry.

How To Dry Out An Alternator

Get a can of CRC electric clean or a similar product and spray it into the alternator, then let it sit for 24 hours. Your alternator should be good to go afterwards. It can also help to leave the hood open to allow airflow through your engine bay to dry it out.

I Got Water On My Alternator Will It Be Fine Once It Dries Off?


Again, alternators are designed to handle water. If your alternator got wet and isn’t working, the problem is likely a wet diode or something similar.

Give your car 24 hours to dry out using the tip above, and your alternator should be good to go.

My Alternator Is Not Charging After I Washed The Engine

Normally this is an issue when someone washes the engine bay while the engine is still on. This is also an issue when you use a power washer – which can destroy your alternator.

If you washed your engine bay with the engine on, your alternator is toast. Your best bet is to just replace if that’s the case.

If you power washed it though, there’s still hope. Follow the instructions above with a can of CRC electric clean and then let it sit for 24 hours. If it’s still not working, then chances are you will have to replace the alternator.

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