更换冷却水泵 (M276) | Leighsr
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Index

Model

Chassis

Engine

Transmission

E350

R350

S550

W251

W212

W221

M276

722.9

M278

Mercedes-Benz

Coolant Pump Replace (M276)

Brand: Mercedes-Benz

Model: R350

Chassis: W251

​Engine: M276 DE35

Transmission: 722.9

Project: Repair

​Labor: 3 hours

Overview

The vehicle's engine water pump is responsible for keeping coolant flowing through the engine. As water pumps get old the internal bearing can go bad causing noise and a coolant leak. A good indicator that your water pump is failing is if you see coolant leaking through the water pump "weep hole".

​

Engine Water Pump Failure Symptoms

  • Coolant leak through weep hole

  • Play at water pump pulley shaft indicating a bad bearing

  • Squeaking noise coming from the pump at idle

  • Overheating conditions

  • Low coolant light on instrument cluster indicating a cooling system leak

Parts & Accessories

Coolant Pump: A 276 200 04 01 (engine no. up to 30022368)

                          A 276 200 13 01  (​engine no. up to 30022368)

                          Check Engine Number

Coolant: Genuine Mercedes Q1030004

               Antifreeze/water=50/50, up to -37°C

               Antifreeze/water=55/45, up to -45°C

Tools

Remove

Step 1  Open The Engine Hood

Substep

1.1 Pull lever (1) in the left side of the footwell to unlock the engine hood (2) Engine hood jumps open; lift engine hood slightly if necessary

1.2 Raise handle (3) and open engine hood. Windshield wiper arms must not be folded forward;​

1.3 Press the red release button (4) on the gas-operated strut and position the engine hood vertically.

Step 2 Lift Vehicle

Substep:

2.1 Jack front vehicle at front central jack point;

2.2 Support vehicle at front side jack points with jack stands;

2.3 Jack rear vehicle at rear central jack point, if w/o rear central jack point, jack at the bottom of differential sell which  fixed at subframe carrier directly;

2.4 Support vehicle at rear side jack points with jack stands.

Step 3 Remove bottom engine compartment paneling

Substep:

3.1 Remove bolts (4) (8 bolts).​

3.2 Remove rear engine compartment paneling (2) Do not lose washers(5) When installing ensure the washer(5) is seated correctly

3.3 Remove bolt (3) (6 bolts).​

3.4 Remove front engine compartment paneling (1)

Step 4 Drain Coolant from Radiator

Substep:

4.1 Unscrew cap for coolant expansion reservoir (1) Unscrew cap slowly and relieve excess pressure;​

4.2 Slide collector siphon hose onto fitting (6) at the radiator, The fitting (6) is located at the bottom left of the radiator. 

4.3 Loosen siphon hose (5) at the radiator and drain the coolant. Observe regulations for disposal of coolant.

Step 5 Disconnect battery ground line

Disconnect-connect battery ground line-1

Substep:

5.1 Move the right front seat completely to the rear;​

5.2 Switch off all electrical consumers to prevent damage;

5.3 Switch off ignition and remove; On vehicles with Keyless Go, Press the start/stop button repeatedly to switch off. Keep the transmitter key away from the vehicle at least 2 m;

5.4 Using a suitable tool moves into the opening of the rail cover (1) (arrow A) and unclip rail cover (1) and move forward (arrow B);

5.5 Lift up the floor covering (2) upwards (arrow C);

5.6 Remove nut (5) to battery negative pole circuit, detach ground line (6) of battery (G1) Ensure that no jumper start device is connected to the vehicle. 6Nm (53 lb-in) for installation.

Step 6 Drain Coolant from Coolant Pump

Substep:

6.1 Loosen drain screw (7) on the coolant pump (8) until it can be turned by hand, 6Nm (80lb-in) +90° for installation;​

6.2 Push drain hose (9) onto the drain screw (7);​

6.3 Unfasten drain screw (7) further by hand and drain off coolant.

Step 7 Remove Belt

Substep:

7.1 Remove front engine cover;​

7.2 Slacken poly-V belt and remove swivel clamping device (1) at hexagon (4) counterclockwise, remove poly-V belt and de-tension clamping device (1) ​

7.3 Check belt pulley sections, the tensioning device (1), and the guide pulley (2). Check poly-V belt Check for damage, wear, and dirt; replace if necessary.

Step 8 Remove partition wall between wheelhouses

Substep:

8.1 Remove engine compartment sealing (1) from partition wall between wheelhouses (5);

8.2 Unscrew screws (2 and 3), 23Nm (204 Ib-in) for installation;​

8.3 Unscrew bolt (4);​

8.4 Pull out partition wall toward the front between wheelhouses (5) and remove.

Step 9 Remove Air Filter Housing

Substep:

9.1 Detach the connector of the airflow sensor;

9.2 Unscrew two bolts for air filter housing;

9.3 Loosen the clamp for intake hose;

9.4 Remove air filter housing.

Step 10 Remove Throttle Body

Substep:

10.1 Detach the connector of the airflow sensor;

10.2 Unscrew two bolts for air filter housing,

        7Nm (62 lb-in) for installation;

10.3 Loosen the clamp for intake hose;

10.4 Remove air filter housing.

Step 11 Remove Coolant Thermostat

Substep:

11.1 Detach electrical connector on the heating element (R48) ;​

11.2 Detach purge line (4) on intake manifold (5) and place to side;​

11.3 Detach coolant hose (7) from coolant thermostat housing (8) ​

11.4.1 Slide nose (2) of catch spring (3) to position (B). Never pull on the eyelet (1). Or the catch spring (3) will lose its pretension;​

11.4.2 Detach hose. Replace sealing ring for installation;​

11.5 Detach coolant line (9) for oil cooler on coolant thermostat housing (8) Replace seal for installation;​

11.6 Remove thermostat housing (8) on timing case cover. The thermostat must not be removed from the housing (8), to prevent destroyed. 8Nm for installation and replace O-ring.

Step 12 Remove Coolant Pump

Substep:

12.1 Detach coolant inlet fitting (6) on coolant pump (1) 

       8Nm (71 Ib-in) for installation and replace seal;​

12.2 Detach guide pulley (7) from coolant pump (1)

        35Nm (26 Ib-in) for installation;​

10.3 Remove bolts for coolant pump (1), For installation replace screw/bolts; observe bolt plan and tightening sequence;​

12.4 Remove coolant pump (1) from the timing case cover;​

12.5 Remove the cover (1a) on the coolant pump (1), 4Nm+120° for installation, and replace the seal (8). Replace cover (1a) since the seal (8) for the coolant pump (1) is integrated into the cover (1a);​

12.6 Clean sealing surfaces on coolant pump (1) and timing case cover with Loctite 7200 and Loctite 7063 cleaning spray.

Installation  (Install in the Reverse Order)

Key 1 Coolant Pump Tightening Procedure and Bolt Plan

Substep:

1.1 Tighten screw/bolts (1 to 11) according to Stage 1 ;​

1.2 Tighten screw/bolts (1 to 11) according to Stage 2.

Tighten Torque

M6 (A)

Stage 1

5 Nm

(44 Ib-in)

Stage 2

10 Nm

(89 Ib-in)

M8 (B)

Stage 1

10 Nm

(89 Ib-in)

Stage 2

20 Nm

(177 Ib-in)

Key 2 Pour in Coolant and Bleed Cooling System

Method 1

Vacuum and fill in the coolant with original equipment;

Method 2

Vacuum and fill in the coolant by aftermarket coolant refiller and compressor;

​Method 3

Pour in coolant at the reservoir to correct level and recheck level at running temperature for self bleed. This method has some risk, and more time, but save money.

Key 3 Some Important Steps

Substep:

3.1 Check coolant level​

3.2 Inspect cooling system leaks​

3.3 Attach ground lead to battery​

3.4 Connect STAR DIAGNOSIS and read fault memory

Faults which may have been caused by disconnecting wires or by a simulation must be erased in the fault memory.

The related operation guides from the MB WIS

Additional Word

The repair program is written according to the repairing booklet of Mercedes and the operation by myself. There will definitely be some incorrect or immature. I appreciate it if you might leave a comment of suggestions to improve the above program, in order to benefit the DIY hobby Needs, thank you!

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