Fuel Injection Pump Identification
External Identification Map
A VISUAL MAP OF External COMPONENTS OF R18Y BOSCH FUEL INJECTION PUMPS
ID Label Breakdown
DECODING A BOSCH INJECTION PUMP'S DISTINGUISHING FEATURES
If you know anything about German engineering, you know they like to keep things simple. Just kidding.
While the engineering and design of components for Mercedes-Benz classic cars already present a high level of complexity, getting information about those parts can prove just as confusing and time-consuming. Not only are the manuals in German, but finding those manuals can be a virtually impossible task.
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Something as simple as understanding a label can become a bit of a nightmare for anyone not already knee-deep in the history and legacy of these parts.
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When it comes to Bosch fuel injection pumps, deciphering the naming code can help you not only identify the exact pump you have and if it is right for your vehicle, but can tell you quite a bit about the pump itself.
So what does "PES6KL 70B120 R20Y" actually mean?
THE BREAKDOWN
Simply put, each letter or number identifies a unique aspect of Bosch fuel injection pumps, helping to identify and differentiate your pump from other generations. Unfortunately for the non-German speaking crowd, the letters don't exactly match up to the translation, but we can give you an idea of what each of those identifiers is telling you.
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In the first grouping, the initial letters (PES in our example) define if the pump is inline (PE) or rotary along with the type of mount. The following number identifies the number of plungers, while the next grouping of letters identify the maximum plunger diameter of 7-7.5mm and if the pump is a mechanical fuel injection (MFI) pump intended for use with gasoline. ​
The second grouping starts with the actual plunger diameter followed by the design change code. An "A" indicates a plunger and barrel element WITH oil blocking while a "B" signifies a pump WITHOUT. The final number in this grouping identifies the location of the fuel feed pump, with 120 indicating the pump does not have a fuel feed pump on the body. ​
The final grouping indicates the series number and an R or L for either a right or left direction of rotation. Some pumps also have an additional letter on the end, in this case a Y indicating the pump is for the US market.
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Take a look at our individual fuel injection pump pages to learn more about your specific pump, or check out our pump map page to find out what's what on a Bosch fuel injection pump. (Pump pages coming soon!)
The space cam sits behind the governor and determines fuel mixture under different load conditions. The hole on the left connects to a lever which rotates the space cam while a stylus reads the grooves on the right, which adjusts the fuel mixture.
W113 Models and Space Cams
The W113, also known as the "pagoda", is quickly becoming a hot commodity in the classic market with prices regularly approaching six figures, and the best models reaching nearly $200K. As these vehicles become more and more collectible maintaining them correctly, along with their plethora of parts, will become more important as each component becomes rarer and more valuable.
Maintaining Bosch fuel injection pumps was already a specialized field with only a few stateside technicians offering the knowledge and know-how, and even fewer with the time to take on new projects. As one of the experts on Bosch fuel injection pumps of the era, we are building a resource to better assist the W113 community on fuel injection pump history, information, and technical specs so that all owners can have access to this vital material and can make the decisions necessary to preserve and restore these icons of automotive history.
The number etched into the side of the space cam determines the model indicated in the right-hand column. While changes may be slight, each cam is specifically engineered for its corresponding fuel injection pump model.
