DIY W202 Steering Damper Replacement

On my car, the steering damper has never been changed, and I can tell it's bad by the way the steering handles in bumps on the road. Anyway, it's supposed to be changed about every 50K miles, plus it's cheap ($27).

1. Buy the steering damper. 
2. Use a 17mm spanner to hold onto the bolt. 
3. Use a 17mm socket on a rachet to loosen and remove the nut. 
4. Repeat for other side.
5. Replace steering damper and fasten the nut/bolt using a spanner and a torque wrench. Torque to 40 Nm. (30 lbf ft).

More Information:
http://www.mbclub.co.uk/forums/wheels-tyres/28562-changing-steering-damper-my-w202.html
http://www.benzworld.org/forums/w202-c-class/1407456-saturday-morning-diy-session-steering-damper.html

Date: 12/30/2010

Mileage: 120K

Total Cost: $27

Time: 5 minutes

DIY W202 Oxygen Sensor Replacement

Whether you like it or not, it is highly encouraged that you change upstream oxygen sensors every 100K miles.
Read all about oxygen sensors here:
http://www.autohausaz.com/html/emissions-oxygen_sensors.html
I'll summarize:

1. The oxygen sensor (previously called the "lambda sensor")  monitors the level of oxygen (O2) in the exhaust so that the ECU can regulate the air/fuel mixture to reduce emissions.
2. As oxygen sensors age, they become sluggish, so they are not quick enough to respond to changes in air/fuel mixture. The voltage they produce is also not as large as they should be, giving the false impression that the fuel is leaner than it actually is, which causes higher gas consumption and higher emissions.
3. An additional consequence of any oxygen sensor failure may be damage to the catalytic converter. A rich operating condition causes the converter to run hotter than normal. If the converter gets hot enough, the catalyst substrate inside may actually melt forming a partial or complete blockage.
4. Second generation heated oxygen sensors used on mid-1990s and newer vehicles are recommended to be changed every 100K miles.
5. Increased fuel consumption, driveability problems (hesitation or surging), "Check Engine Light" lit or emissions test failure could all be signs of an oxygen sensor in need of replacement.

At 120K miles, I've already seen enough roughness and surges at low speeds to suggest incorrect air/fuel mixture. Considering the fact that I've already changed my Mass Air Flow (MAF) sensor, what's left is the front oxygen sensor, which together with the MAF are used by the ECU to do closed-loop control of the air/fuel ratio.
As for the rear (downstream) sensor, it only needs to be changed if it throws a code or the Check Engine Light turns on.
So here's how to replace a front oxygen sensor for my 1999 C230 Kompressor.

1. Buy a new OEM front oxygen sensor (~$100)
2. Buy an oxygen sensor removal socket (I got the larger one).
3. Loosen and remove the oxygen sensor from the exhaust manifold. It may need to be loosened by heating the exhaust manifold and/or using WD-40 or Pb-Blaster. If any of these compounds are used, they should be cleaned off before fitting the new sensor on to avoid contaminating the new sensor. Heating the exhaust manifold can be done by turning on the engine and idling for two minutes at a time (one or more times) until it just hot enough to remove the sensor.
4. Cool down before installing the new sensor.
5. Install the new sensor with sensor-safe anti-seize for easy removal the next time you change it. Some sensors come with enough lubricant from the factory to save you the trouble. Torque the socket to 55 Nm (44 lbf ft).
6. Tie the new sensor (at the plug end) to the old sensor (at the sensor end) and pull on the old sensor (plug end) from the top and swap out the new sensor with the old one at the wiring harness leading to the ECU.
7. Make sure the wire doesn't touch any hot surfaces (like the exhaust manifold).

Additional Info: 

http://www.mbclub.co.uk/forums/engine/41615-w202-c230k-lambda-sensor-when-should-you-replace.html

http://www.benzworld.org/forums/r170-slk-class/1277304-upstream-oxygen-sensor.html

http://www.mbworld.org/forums/c-class-w203/206488-diy-m271-o2-sensor-replacement.html

http://www.benzworld.org/forums/r129-sl-class/1421450-diy-oxygen-sensor.html

Additional Notes: The coolant temperature sensor is also a good sensor to replace at this mileage. It also affects the ECU's decision to control the air/fuel mixture.

Date: 12/30/2010

Mileage: 120K

Cost: $100

Tool Overhead: $12

Time: 20 minutes

DIY Custom Power Bleeder Construction

I have a brake job coming up. Rear pads and rotors need to be changed. I was thinking of replacing them with Akebono Euro Ceramic Pads and ATE rotors. I read good reviews about them on forums. But more about that later.

Since my brake fluid hasn't been flushed since I got my car in 2008, a brake fluid flush is due.

Reading forums, I came across these instructions for building your own power bleeder, so I did.

http://www.benzworld.org/forums/w210-e-class/1355714-how-make-your-own-power-bleeder.html

Here are links to where I got the parts:

1. Watts 3/8 in. O.D. x 1/4 in. I.D. x 20 ft. PVC Tubing ($4.69)
2. Watts 1/4" Barb x 1/4" MIP Brass Hose Adapter 
3. Watts 1/4 in. x 1/8 in. Brass MIP x FIP Hex Bushing ($1.45)
4. RL Flo-Master 1.5-Gallon Polyethylene-Tank Sprayer ($11.50)
5. Genuine Mercedes Brake Fluid Reservoir Cap ($9.64)
6. Low Pressure Air Gauge ($4.50 + $3.50 S&H)
7. Teflon Tape ($1.18)
8. J.B. Weld ($4.97)

Here's are alternatives

http://www.bmw-m.net/TechProc/bleeder.htm

http://www.bayarea02.com/techtips/brake_bleeder.html

http://www.ibmwr.org/ktech/pressure-bleeder/bleeder.shtml

Cost Break Down of Repairs on My Car

I'll be organizing the break down of the cost for the repairs on my car to track my spending in Parts and Labor for different repairs on my car.

Here's a link to the spreadsheet.

DIY W202 Spark Plugs and Ignition Coil Replacement

At close to 120K, I replaced my ignition coils and spark plugs today.

Last time I changed spark plugs was about a year ago, after I had gotten a misfire in one of my cylinders. I changed the spark plugs and the wire set back then, but the Check Engine Light didn't go off. I later had to clean the mass air flow sensor twice before it went off. (It this had happened today, I would have just replaced the mass air flow sensor).

I didn't need to change the wire set now, but since the ignition coils were the factory installed ones and I suspected they were going bad. I had lost engine power and there was a rattling noise that really bothered me (and my passengers).

Immediately after the change, I noticed the restored power and the rattling noise was gone.

Date: 12/23/2010
Mileage: ~120K
Ignitions coils: 2x$64
Spark Plugs: 4x$4.50
Total Cost: $146
Time: 30 minutes

DIY W202 Throttle Actuator Cleaning

In an effort to improve my idle performance, I decided to clean the Throttle Actuator in case it had gotten dirty.

I read my Haynes manual to remove it completely and used CRC Throttle Body and Air Intake Cleaner ($8) also available at any auto parts shop like Autozone.

When I put it back together and drove my car for the next few days I noticed really bad performance after a cold start. I suspected the washers had to be replaced. So I went to my local dealer and got these parts: 000 140 27 87 (Damper) for $11.38 and 111 141 10 80 (Gasket) for $4.47, corresponding to the parts labelled 71 and 48 respectively in the following picture.

Sure enough, the problem was solved.

Date: 12/15/2010
Mileage: 119K
Total Cost: $25
Total Time: 1 hour

DIY W202 Air Mass Sensor Replacement

My car once had a Check Engine Light (CEL) and I cleaned my mass air flow sensor twice and the light went off, but recently I had bad acceleration and decided to invest in a new sensor.

Although you can buy a whole air mass sensor assembly from autohausaz.com, you can save some money by getting the insert only at GermanStar.net , or as I found this seller on eBay:

AutoLampsPlus.com Air Mass Sensor

Date: 12/14/2010
Mileage: 119K
Price: $91
Time: 5 minutes