Monday, May 14, 2012

Water treatment for W124



If you had driven on a rainy day and encountered better engine performance, this is most likely due to the moisture in the air going into the intake and aiding the combustion in the engine.

So how to prolong or make the engine performance a permanent effect without waiting for a downpour?

Water injection is the key!

Water injection is not a new discovery. It has been commonly used for racing engines, especially for turbocharged engines. According to Wikipedia entry on the subject, water injection cools the combustion chamber and creates greater compression ratios and also eliminates engine pinging. It is also said to be able to increase the octane rating of the air fuel mixture.


Though the naturally aspirated engines do not require water injection, the resulting steam from the water entering the hot engine, does have cleaning properties and may assist to reduce pinging/knocking. This is particularly useful for older cars like the Mercedes W124.

The method of pouring water into the engine (slowly) has also been used for many old carburetor cars. ( see references on bottom of post )

The engine should be warm (the hotter the better for decarbonizing with water) when performing the water treatment to ensure that the water going into the intake will steam up before it reaches the combustion chamber. The steam is said to be able to de-carbonize the carbon present in the valve-seats and achieve better compression.

To do this, the air-filter box should be opened. Use a 500ml mineral water bottle and poke a small hole at the cap. The engine should be revved to 2k rpm or more when water is entering the air intake. 

Time the stream of water to be about 1 sec each cycle to see how the engine reacts. Again, it is important to note that the throttle should be slightly open to achieve 2k rpm or more when water is entering the intake. The trick will be to keep the engine running while water is entering the intake as the engine's rpm might decrease during this process.

To finish up the 500ml of water will be a lengthy process as it will consist of many cycles. It'd be best for the job to be done by 2 persons with one holding the throttle and another doing the water spray.

Once that is done, turn off the ignition and it is very much recommended to spray some carb cleaner into the air-intake and throttle body to prevent rust. Before spraying the carb cleaner, ensure the throttle is at its wide open position so that the carb cleaner spray will be able to enter the areas under the throttle flap. Let the carb cleaner settle for a good 15 minutes before starting the engine again.




Note : This is an alternative maintenance procedure and not meant to be done often.

So if you have a engine knocking issue and would like to try a relatively low cost and harm free method to solve the problem, the radical water injection treatment might just be it.