How To Own A Ridiculously Cheap And Reliable Mercedes S-Class

Illustration for article titled How To Own A Ridiculously Cheap And Reliable Mercedes S-Class

It's no secret - I'm a huge fan of the Mercedes W220 S-Class. With its insane depreciation curve and world-beating ride comfort, driver experience, and unmatched opulence, it becomes a nearly unbeatable value in today's used car marketplace. Today I'm going to show you how to make it the most reliable car you've ever had.


The Fault

The 2000-2006 W220 S-Class is a technological masterpiece, with more than 200 individual patents filed for its proprietary systems. It has a myriad of computers handling its various and numerous features, but it has one major Achilles' heel: the inside can flood from a light drizzle, rendering the car inoperable with the very real potential for thousands of dollars in damage. The cause is a 2-inch wide vent at the bottom of the front cowl, known as the reed valve, that over time, gets clogged with debris and floods the chamber, causing water to flow over the cowl, into the cabin, underneath the carpet, and shorts out the rear Signal Acquisition Module (SAM) and fuse box underneath the rear passenger's side seat. In a car with a near 6-figure MSRP when new, this was, and still is, a huge oversight. Here's an example of how extensive the damage could be:

While this may be a major fly in someone's burlwood-and-Nappa-leather-covered ointment, it is one of the major reasons that a good condition S-Class can be had for less than the price of a Used Honda Civic. Just check what they're going for on eBay and wonder why you ever thought a base model Civic was ever an option.

Also, for those also worrying about the sometimes expensive Airmatic suspension components failing, check out how I remedied them reasonably with virtually no downtime in this article.

The Fix

This fix, although a bit dirty, is the single most important thing you can do to your S-Class next to oil changes and making sure your climate control adequately filters the smell of poverty from the cabin. If you're worried about this issue rearing its wet ugly head, you have a few options:

1. Clean Out The Reed Valve

What one possible solution entails is basically cleaning out the cowl and clearing the debris from the valve, using a stick, as seen on, by dkimnyc:

Illustration for article titled How To Own A Ridiculously Cheap And Reliable Mercedes S-Class

2. Drill An Emergency Hole In The Cowl

This solution is brought to you by Mercedes itself. Here's the schematic of where to drill the hole. Although it doesn't deal with the actual reed valve issue, it does provide a stopgap between the reed valve failing and the the cabin flooding.


3. Remove Reed Valve Completely

Illustration for article titled How To Own A Ridiculously Cheap And Reliable Mercedes S-Class

While the above methods can be effective remedies, I have devised a procedure to be a bit more permanent and efficient:

1. Open the hood

2. Locate the passenger's side cowl vent

3. Take off the vent grille by pulling up with your fingers

4. Remove debris/dirt from entire cowl area, wipe down thoroughly

5. Find the reed valve at the bottom.

6. Place finger in reed valve.

7. Pull up, removing reed valve.

8. Re-install vent grille.

9. Enjoy an S-Class that doesn't flood.

By removing the reed valve, any water should flow directly down and through the drain, leading below the car. Although this is a permanent fix, you should periodically check the drain for leaves, twigs, and anything else that could hinder the flow of water away from the sensitive electrical components and clean it out accordingly. With this simple, cheap, and crucial step, you'll have an S-Class that you won't need to worry about in car washes, rainstorms, or surprise water polo tournaments.


While this isn't the only common problem in the W220, it is on the top of the list of the most widely spread and easiest to fix. If you shop right and budget for some repairs over time, there shouldn't be any wallet-draining issues on this model. Without a doubt, it's the best car value in the market today, and it will change your life. Find one of your very own right now.

For more fixes of otherwise spectacular cars, check these out:


Tavarish is the founder of APiDA Online and writes about buying and selling cool cars on the internet. He owns the world's cheapest Mercedes S-Class, a graffiti-bombed Lexus, and he's the only Jalopnik author that has never driven a Miata. He also has a real name that he didn't feel was journalist-y enough so he used a pen name and this was the best he could do.


You can also follow him on Twitter and Facebook. He won't mind.


Ash78, voting early and often

With all that drilling and finger probing, maybe they should call it the Tara Reid Valve, amiright!?

Why did Leno fire me in 2003?

Funny, this is a very similar problem to the B5-era VW and Audi cars, where some vital chassis electronics were stashed under the driver floor and would get wet from the exact same type of underhood or sunroof drain issue — or even just repeated ingress with wet shoes on (the ironically named Weathertech mats can do just as much to HOLD moisture underneath as they can to protect from it.)

It's funny because in so many ways, the Germans think of everything, but in select few other ways it's just a facepalm of impracticality.

I'm surprised the TSB didn't just tell you to keep the car away from water.