Mercedes-Benz Parts Catalog Mercedes-Benz Accessories Catalog Mercedes-Benz Technical Articles Mercedes-Benz Tech Forums
 
Follow Pelican Parts on Facebook Follow Pelican Parts on Twitter Follow Pelican Parts on Instagram Follow Pelican Parts on YouTube Follow Pelican Parts on Pinterest Follow Pelican Parts on Tumblr
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
 >  >
Engine Coolant Reservoir Replacement
 
Bookmark and Share

Pelican Technical Article:

Engine Coolant Reservoir Replacement

Kerry Jonsson

Time:

3 hours3 hrs

Tab:

$100

Talent:

**

Tools:

Phillips head screwdriver, small straight blade screwdriver, pliers, slip joint pliers

Applicable Models:

Mercedes-Benz W211 (2003-09)

Parts Required:

Coolant reservoir

Hot Tip:

Make sure the car is fully cooled off before attempting this repair

Performance Gain:

Eliminate coolant leak from cracked coolant reservoir bottle

Complementary Modification:

Flush the coolant at the same time

While your engine is running it produces heat. Your cooling system is designed to circulate coolant around the engine block and absorb most of this heat. It is then circulated through a radiator and passes through small pitch fins. As you drive or a cooling fan turns on, air is drawn in through the radiator. As the air passes through the small pitch fins of the radiator it absorbs the heat from the hot coolant passing through it. This lowers the temperature of the coolant as it passes through the radiator. The process is repeated where the cooled coolant is returned to the block to absorb more heat and back to the radiator to dissipate the heat from the coolant.

Straight water should not be used in a cooling system since it will start to boil at 212 degrees Fahrenheit (100 degrees Celsius). When the coolant starts to boil this is known as overheating and engine damage will start to occur. A 50 / 50 mixture of coolant and water gives the broadest range, with the highest boiling point for summer driving and the lowest freezing point for winter storage. Coolant expands slightly as most liquids do when heated up. Engineers discovered if the cooling system is under some pressure the boiling point of the coolant will rise making the coolant less likely to boil over. Mercedes Benz engineers use a pressurized remote coolant reservoir to deal with the expansion and contraction of engine coolant as it heats up and cools off. When the coolant is cold you will see it at the lower coolant level. When the coolant is hot you will see the level rise slightly in the coolant reservoir. Over time the cooling reservoir can crack from all these heat cycles. If it does you can lose coolant and eventually you will lose enough and the engine will "overheat". In this tech article we will show you how to replace your coolant reservoir.

Engine coolant can get over 212 degrees (100 degrees Celsius) while the engine is running. Never open a hot coolant reservoir. The system will depressurize and hot coolant can come pouring out burning you badly. If you are going to do this job make sure the engine is fully cooled off before attempting to remove the coolant reservoir cap.

ThisPicture illustrates the front of the engine compartment on the left side.
Figure 1

This picture illustrates the front of the engine compartment on the left side. Remove the coolant reservoir cap and use a suction gun to remove as much coolant as you can from it.

Using a Phillips head screwdriver loosen the center plastic rivet screw, then remove the plastic rivet with the screw (green arrow).
Figure 2

Using a Phillips head screwdriver loosen the center plastic rivet screw, then remove the plastic rivet with the screw (green arrow).

Using a small flat head screwdriver lever up on the metal retaining clip for the bleed line hose.
Figure 3

Using a small flat head screwdriver lever up on the metal retaining clip for the bleed line hose.

Twist the bleeder hose (green arrow) slightly to break loose the seals and pull it out of the coolant reservoir.
Figure 4

Twist the bleeder hose (green arrow) slightly to break loose the seals and pull it out of the coolant reservoir.

Pull up on the coolant reservoir until you have unseated the two tabs (green arrows) from the rubber mounting grommets (yellow arrows).
Figure 5

Pull up on the coolant reservoir until you have unseated the two tabs (green arrows) from the rubber mounting grommets (yellow arrows). One rubber grommet on the right side of this photo is missing, I will have to replace this item before reassembling the coolant reservoir.

Rotate the coolant reservoir slightly to expose the coolant level sensor on the underside of it.
Figure 6

Rotate the coolant reservoir slightly to expose the coolant level sensor on the underside of it. Squeeze the locking tab (green arrow) on the bottom of connector and unplug the electrical connector by pulling it in the direction of the blue arrow.

Using a pair of pliers squeeze the spring clamp and move the clamp down the hose.
Figure 7

Using a pair of pliers squeeze the spring clamp and move the clamp down the hose. Here we are using needle nose vise grip pliers to hold the spring clamp.

Using slip joint pliers grab the hose and twist if first to break the seal between the hose and the coolant reservoir.
Figure 8

Using slip joint pliers grab the hose and twist if first to break the seal between the hose and the coolant reservoir. When removing the hose, keep it elevated as high as possible to prevent any coolant from spilling out of it. This will reduce the amount of bleeding of the cooling system upon reassembly.

Remove the hose from the coolant reservoir.
Figure 9

Remove the hose from the coolant reservoir. Have a drain pan underneath the work area since some coolant may still be left in the bottle. Installation is the reverse of the removal steps. Fit the hose on the coolant reservoir, position and release the spring clamp where the hose fits onto the coolant reservoir. Plug in the coolant reservoir level sensor electrical connector. Position the two tabs on the coolant reservoir and fit them into the two grommets in the body of the car. Insert the plastic rivet to mount the back of the coolant reservoir to the body. Fill the system and bleed it according to our article on draining, filling and bleeding the cooling system.

Bookmark and Share
Comments and Suggestions:
Fern Comments: Do you need to flush the coolant or can you use the same coolant if it was recently flushed?
May 3, 2016
  Followup from the Pelican Staff: You can reuse the coolant. Be sure to drain and store it in a clean container. This will prevent debris from getting into your cooling system. - Nick at Pelican Parts  
harrye500 Comments: Great directions!
as a very very amateur fix it person some comments:
- fig 2, used needle nosed pliers to pull screw out, bc kept spinning
- fig 9, another set of hands is helpful, one to hold spring clamp, other to separate hose from reservoir
December 19, 2015
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 

  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    

 

[Home] [Customer Service] [Shopping Cart] [Project/Wish List]
  [Privacy Statement]  [Contact Us] [About Us] [Shipping] [Careers]

Copyright © Pelican Parts Inc. -    DMCA Registered Agent Contact Page

Page last updated: Sat 12/3/2016 02:31:30 AM