Correct use and maintenance of the Aquatarder / Retarder system Mercedes-Benz Actros MP4
Introduction

The Aquatarder system (or liquid-cooled hydraulic retarder) installed on the Mercedes-Benz Actros MP4 is an essential element of the auxiliary braking system, designed to take over part of the load of the service brakes. Used and maintained correctly, it offers major benefits: increased safety on long descents, reduced wear on the main brakes and more economical operation of the vehicle.

The Mercedes-Benz AG manual (P/11/23, AN20.00-W-0001A) specifies in detail the installation and maintenance procedure for the retarder unit and the additional coolant filter.

Correct installation of the retarder

According to official instructions, installation should only be carried out in an authorized service by qualified personnel familiar with the auxiliary braking systems for Mercedes trucks.

Essential steps before installation

Complete inspection of the cooling system – identifying possible causes of faults or deposits.

Complete cleaning of the circuit – removing all residues and contaminants.

Replacement of affected components – damaged pipes, connections, seals.

Filling the engine with approximately 15 litres of “Frostox S” solution mixed with distilled water.

Starting the vehicle and driving it for 30 km to allow the solution to circulate completely.

Draining and flushing the cooling system.

Refilling with the manufacturer’s recommended coolant: Original Mercedes-Benz G40.

Scheduling an annual coolant change or earlier, depending on the frequency of use of the retarder.

Installation of the additional coolant filtration system, according to Annex AN20.00-W-0001.

Installing the coolant filter

The official document precisely describes the installation of the retrofit filter and cooling lines on the OM 471 / 473 engine.

Among the main steps:

Replacing the drain plug on the crankcase with a dedicated connection fitting (torque 30 Nm);

Mounting the filter on a solid support of the steering system, using M8x20-M8x25 screws;

Connecting the supply and return hoses, protected with anti-friction heat shrink tubing;

Installing the check valve, with verification of the correct direction of fluid flow;

Testing the tightness of all connections by a test at idle and at medium speed.

After completion, the vehicle documentation (VeDoc) must be updated with the codes:

SAA 54225425 for the coolant filter;

SAA 54225429 / 54225430 for the connection fittings;

Addition of the equipment code M8T (coolant filter) in the vehicle data sheet.

Maintenance parameters

After installing the system, the central control unit (CGW) must be parameterized for:

Maximum service interval: 150,000 km;

Maximum service interval: 1 year.

In addition, all hoses and protections must be checked regularly for chafing, vibration or leaks.

Preventive maintenance and operating recommendations

Change the coolant and filter cartridge every 12 months;

Use only G40 antifreeze or Mercedes-approved equivalent;

Check the magnetic drain plugs for metal particles;

Inspect the electrical connectors and check valve regularly;

After each major intervention, run a leak test and update the maintenance log.

Conclusion

A Mercedes-Benz MP4 Aquatarder installed and maintained according to specifications offers excellent reliability, reduces operating costs and makes a significant contribution to road safety.

Implementing the coolant filtration system and adhering to the service intervals recommended by Mercedes-Benz are essential conditions for optimal retarder operation.

West Tech Diesel recommends that users and partner workshops strictly follow these instructions, in order to ensure the long-term performance of each Aquatarder unit installed on the Actros MP4.