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Since 2012 until September 2019 over 800 sets of mechanical diesel fuel injectors have been serviced using a perfected system which will make your injectors look like new and perform like new when new nozzles are installed. Hobbyists are passionate about their cars and that passion is channeled into this injector service.   All makes and all models, such as Mercedes, VW, GM, LandRover, Toyota, et cet.  The Guru is a trusted name in 16 countries, over six continents within the last seven years.

Terms and Conditions

NO NEW AND NO USED NOZZLES ARE SOLD BY DIESELFUELINJECTOR.GURU. ONLY A SERVICE IS BEING PROVIDED.  By paying the service fee, the Buyer manifests its agreement to the Seller’s terms and conditions which are as follows:

   1. The Seller warrants, represents, and guarantees that the Buyer’s diesel fuel injectors will be rebuilt with the same processes, care, and attention to detail since the Seller started doing mechanical diesel fuel injectors in 2012.  The procedures used in the Seller’s diesel fuel injector service consists of a multi-bathe process performed over a 48-96 hour period whereby all carbon, grease, scale, rust, and other contaminates are removed, and a final cleaning in an ultrasonic cleaner is utilized. Absolutely no acids, no caustic sodas, or other harsh chemicals are used. No mechanical means of cleaning, e.g., wire brush, et cet are used either.  

 2. The Seller is only selling a service to the Buyer, and that service consists of testing, disassembling, cleaning, shimming, re-assembling, and pop testing the Buyer’s re-buildable mechanical diesel fuel injectors and returning those serviced injectors to the Buyer.   

3. All services are guaranteed for 30 days from any defects in the services provided and the 30-day warranty period commences on the day the injectors are delivered to the Buyer. The warranty covers all issues such as leaking at the halves, perceived nailing, et cet. The Buyer shall notify the Seller within this 30-day period to exercise any warranty claim. Once notified, the Buyer shall ship the injector(s) back to the Seller indentifying the perceived problem(s) within seven (7) days. If the problem originated from the Seller’s service, the Seller shall pay for the shipping to and from the Buyer for the returned work. The shipping is capped at $7.00 each way. There is no warranty of any kind whatsoever after the expiration of the 30-day period. 

  4. There are no refunds as the service is provided upon servicing of the Buyer’s mechanical diesel fuel injectors; therefore, please ensure you want your injectors serviced.   

5. All diesel fuel injectors are shimmed to meet-or-exceed the specifications in the factory service manual except those whereby the Buyer specifies custom or unique PSI ratings.   

6. The turn-around time is seven (7) days and the seven days commences on the day the Seller receives the Buyer’s mechanical fuel injectors. If the seventh day falls on a Sunday or legal holiday, then the seven day period starts on the next business day.  Injectors will be shipped the next business day. (Normally, injectors are completed within three to four days, however, the seven day window is provided for maximum flexibility.) Seller and Buyer can agree in advance for faster completion times. In the event the injectors will take more than seven days, the Seller will notify the Buyer.   

7. The Buyer’s injectors will be shipped through the United States Postal Service, flat rate, Priority Mail® with insurance meeting or exceeding the service fee paid to the Seller. However, the USPS generally only pays claims for the amount the item costs and not insured for.   

8. Only re-buildable mechanical diesel fuel injectors shall be sent to the Seller; broken barbed fittings, cross-threaded ports, cracked halves, or other issues render any mechanical diesel fuel injector unfit for service. In the event a non-detectable problem is encountered by the Seller, the Buyer will be notified to ascertain the best route to take to correct the problem, e.g., providing additional injectors, returning the set, et cet. In the event there are returns because an incomplete set will not be serviced, the Buyer shall only pay for the shipping back to him / her. This shipping is capped at $12.00.   

9. The Seller shall not undertake any work until the Buyer pays the service fee. The service fee as quoted here is valid for the remainder of 2019.  Pricing will be going up in 2020 as pricing has been fixed for the past two years yet consumbables have increased in price:    

A. Sets of 4 $79.00 shipped CONUS

  B. Sets of 5 $99.00 shipped CONUS

  C. Sets of 6 $119.00 shipped CONUS  

D. Sets of 8 $159.00 shipped CONUS   

The service fee covers all expenses, such as PayPal® fees, shipping & insurance fees back to the Buyer, and the price for the service fee. OCONUS (outside the continental United States) Buyers shall pay the shipping fees as agreed upon in advance. The Seller has performed injector service work for Buyers in every continent except Antarctica and there is no uniform optimal shipping solution for all OCONUS locations. Overseas Buyers please contact the Seller in advance before placing any orders.   

10. The Buyer shall either provide new nozzles (and internal heat shields depending on the injector, et cet)  to the Seller or have the existing nozzles in the Buyer’s nozzle holders serviced.   

11. Payment through PayPal® or USPS money order is the only acceptable means of payment.  

12. The Buyer’s serviced injectors will be shipped to the PayPal® address on record at PayPal® or the shipping location specifically identified by the Buyer.   However, the Paypal address is the default address.

13. The Buyer shall specify in advance turbo or naturally aspirated (NA) settings or custom settings. If the Buyer fails to specify in advance the settings sought, the Seller will automatically shim the injectors to the stamped settings on the injector bodies.   

The above represents all terms and conditions between the Seller and Buyer. These terms and conditions seek to address issues as they developed over the years. The terms and conditions may change in the future without further notice. Please provide any suggested changes to Mark@dieselfuelinjector.guru   

Videos, Pictures, and Updates



This is how your injectors will look inside and out -- near surgically clean -- when the service is completed.

Injectors can be shimmed and pop-tested at OEM, or fuel sippers or high performance.

As a general reference, nozzles with over 100,000 miles on them are worn; however, to what extent is unknown until bench testing is performed. Nozzles exceeding 150,000 miles are worn to an extent where they “pee” pre or post pop, or both in addition to a poorly performing spray pattern, e.g., split cone pattern, et cet. Once a nozzle is worn, it is worn – there is no refurbishing a worn nozzle.  

There is one remaining German maker of Nozzles - Monark.  Monark merged with DES  "Dresdner Einspritz Systeme" in 2014 so the nozzles you acquire may come in tubes labeled "DES."  Same machines, same German quality.  Until recently, MercedesSource.com had a virtual monopoly selling Monark brand nozzles in the USA.  Now, some vendors are selling them on Ebay.  There are three vendors selling Bosio in  the USA. Bosios are made in Italy and they are a quality nozzle also.  Bosch brand are either made in India or China; however, Bosch brand have a 30-50% fail rate out of the tube.  Bosch brand NOS were made in France.

 Within www.dieselfuelinjector.guru are links to vendors selling Monark Automotive GmbH or Fratelli Bosio s.r.l nozzles. Bosch™ nozzles are either made in India or China, and because there are so many ‘knock-offs’, their quality is always suspect.    




Pictures and Details


A little history for the Mercedes Community:

From 2013 to 2019 approximately 125 Mercedes steering boxes have been serviced for classic Mercedes’ owners. First, the passion started off rebuilding boxes for personal use. Then for other family members, then friends, and then for the entire Mercedes community. The reputation is spread all over the entire Mercedes’ community. The passion is fully directed into the hobby and rebuilding steering boxes. After years restricted to the forums, it is time to showcase the talents and services here on a more universal platform.

Along the way, a few special tools were machined and the process was improved over the years, making rebuilds more efficient and the adjustments more accurate. Several types of paint were tested and the optimal solution is reached in the process. All service procedures as described in Mercedes Benz Chassis and Body Series 123 Volume 1 sections 46-220 and 46-070 for W123 series boxes, or the Mercedes Benz Chassis and Body manual for the Buyer's steering box are followed. All steering boxes are cleaned externally, inspected for damage and play, then disassembled and cleaned with mineral spirits or appropriate grease cleaner depending on the condition of the steering box. Steering boxes are assembled with Castrol Dexron-III/Mercon ATF F-30341 (as approved by MBNA Factory Approved Service Products list) and petrolatum/Vaseline (as temporary assembly grease). Steering boxes are adjusted, without pressurized fluid and separate of any vehicle, as close as possible to the specifications outlined in Mercedes Benz Chassis and Body Series 123 Volume 1 sections 46-220 and 46-480. 

All workmanship is guaranteed for six months from any defects and the six month warranty period comes with other terms and conditions – The below pricing beats anything out there.

Core prices are as follows. 

-W123 power steering (internal or external lock): $75

-W124 power steering: $75

-W126 power steering (with or without play compensation): $75

-W140 power steering: $75

-R107 power steering: $75

-R129 power steering: $75

Reconditioned power steering box*, painted and supplied with locking bolt: $165.00 

 Shipping to CONUS: $55 

*Boxes to be reconditioned are power steering boxes from chassis W123, W126, W124, W126, W140, R107, and R129. 

Contact: mbsteeringboxes@gmail.com



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Bosio & Monark Vendors


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