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    
 >  >
Mercedes Water Pump Replacement
 
Bookmark and Share

Pelican Technical Article:

Mercedes Water Pump Replacement

Steve Vernon

Time:

4 hours4 hrs

Tab:

$110

Talent:

***

Tools:

8mm socket, E10, E12, E14, T-50 Torx driver, flathead screwdriver

Applicable Models:

Mercedes-Benz C320 (2001-04)
Mercedes-Benz CLK320 (1998-04)
Mercedes-Benz E320 (1998-04)
Mercedes-Benz ML320 (1998-03)
Mercedes-Benz S320 (1998-99)
Mercedes-Benz SLK320 (2001-03)

Parts Required:

New water pump and gasket

Hot Tip:

Keep track of where the bolts go

Performance Gain:

Properly cooled engine

Complementary Modification:

Replace your radiator hoses

When a water pump begins to fail, you'll notice that the car tends to overheat at low engine speed, such as sitting at a stoplight. When you accelerate, the engine temperature will drop. Now, this is not always indicative of a water pump, but a good starting point. You may also want to try squeezing the top radiator hose with the engine warmed up and running. You should feel pressure build up on the back of the hose and surge once it is released. If you feel no pressure, it's a fair bet that the water pump is failing.

Replacing the water or coolant pump on W203 is certainly a doable job for a DIY'er but it is not a quick job. If this is one of the first projects you are attempting on your car, give yourself at least five hours to get the job done and don't forget to refill the coolant.

There are several things that will need to come off or out of the car to replace your water pump including the air filter ducts, engine cover, fan and you will need to drain the coolant as well. This is also a very good time to replace your hoses if they are getting on in age.

Please see our articles on replacing your air filter to remove the ducts and cover. Please see our article on replacing your fan to remove the fan and please see our article on replacing your radiator hoses to drain your radiator.

This article begins at the point that you have completed all the other work to get to this point.

You are going to remove the Poly-V belt to remove the coolant pump as well as remove the idle pulley. Inspect your belt and replace as needed. With an E10 (reverse Torx socket) and driver locate the tensioner and using the Torx driver turn it counter-clockwise 45 degrees. You can now slip the belt off the tensioner. You can also lock the tensioner into the open position if you need both hands to install the new belt. Turn the tensioner all the way counter-clockwise and insert a retaining pin between the rotating part and the tensioner base. If you do not have a retaining pin you can use a 5mm Allen key.

To remove the coolant pump you will first need to remove the idle pulley which is located right above the coolant pump pulley. Insert a flathead screwdriver between the cover plate and the pulley and gently pry the plate off. With the plate off use a T-50 Torx and remove the pulley bolt. The bolt is extra long so make sure to label it as it is not easy to replace if you loose it.

Move to the two hoses that connect to the lower part of the coolant pump. Remove the hose that goes to the auxiliary coolant pump from the clip that holds it to the alternator bracket. Next using a flat head screwdriver, remove both hoses. You may need to run the screwdriver between the hoses and housing to help break any seal that has developed.

Two of the bolts that hold the pump in place also hold the bracket for air pump check valve. Use an E10 and remove these two bolts first and then zip tie the bracket out of the way.

Remove the electrical connection for the coolant temperature sensor as you do not damage it while removing the pump.

Next, remove all the bolts that hold the pump to the engine including the one that supports the alternator.

There are one E14, four E12 and twelve E10 bolts connecting the coolant pump to the engine and most of them are different lengths. I like to take an old cardboard box and draw an outline of the pump on it, as I remove each bolt I stick it in the cardboard where came off so I will know where to put it back when I put the new pump on.

Remove the old pump and inspect it for damage.

Remember to replace the gasket whether you are installing a new pump or putting the old one back on.

Installation is the reverse of removal and don't forget to fill up the system with coolant

Note: If you have not read the article and just like to use the pictures to help you, there are several procedures you need to perform before getting to this point, please refer to the article for the steps needed to get to this far.

You are going to remove the Poly-V belt to remove the coolant pump as well as remove the idle pulley (yellow arrow).
Figure 1

You are going to remove the Poly-V belt to remove the coolant pump as well as remove the idle pulley (yellow arrow). This picture illustrates the routing of the belt for reference when it is time to reinstall it. The red arrow shows the belt tensioner. Note: most of the front of the car has been removed to better illustrate the procedures, you do not have to remove anything other than what is listed in the article.

With an E10 (reverse Torx socket) and driver locate the tensioner and using the Torx driver turn it counter-clockwise 45 degrees (red arrow).
Figure 2

With an E10 (reverse Torx socket) and driver locate the tensioner and using the Torx driver turn it counter-clockwise 45 degrees (red arrow). You can now slip the belt off the tensioner.

You can also lock the tensioner into the open position if you need both hands to install the new belt.
Figure 3

You can also lock the tensioner into the open position if you need both hands to install the new belt. Turn the tensioner all the way counter-clockwise and insert a retaining pin between the rotating part and the tensioner base. If you do not have a retaining pin you can use a 5mm Allen key (red arrow).

To remove the coolant pump you will first need to remove the idle pulley which is located right above the coolant pump pulley.
Figure 4

To remove the coolant pump you will first need to remove the idle pulley which is located right above the coolant pump pulley. Insert a flat head screwdriver (red arrow) between the cover plate and the pulley and gently pry the plate off.

With the plate off use a T-50 Torx (red arrow) and remove the pulley bolt.
Figure 5

With the plate off use a T-50 Torx (red arrow) and remove the pulley bolt.

The bolt (red arrow) is extra long so make sure to label it as it is not easy to replace if you loose it.
Figure 6

The bolt (red arrow) is extra long so make sure to label it as it is not easy to replace if you loose it.

Move to the two hoses that connect to the lower part of the coolant pump.
Figure 7

Move to the two hoses that connect to the lower part of the coolant pump. Remove the hose that goes to the auxiliary coolant pump from the clip (red arrow) that holds it to the alternator bracket.

Next using a flat head screwdriver, remove both hoses (red arrows).
Figure 8

Next using a flat head screwdriver, remove both hoses (red arrows). You may need to run the screwdriver between the hoses and housing to help break any seal that has developed.

Two of the bolts that hold the pump in place also hold the bracket for air pump check valve (red arrows).
Figure 9

Two of the bolts that hold the pump in place also hold the bracket for air pump check valve (red arrows). Use an E10 and remove these two bolts first and then zip tie the bracket out of the way.

Remove the electrical connection (red arrow) for the coolant temperature sensor as you do not damage it while removing the pump.
Figure 10

Remove the electrical connection (red arrow) for the coolant temperature sensor as you do not damage it while removing the pump.

There are one E14 (green arrow), four E12 (yellow arrows) and twelve E10 bolts (red arrows) connecting the coolant pump to the engine and most of them are different lengths.
Figure 11

There are one E14 (green arrow), four E12 (yellow arrows) and twelve E10 bolts (red arrows) connecting the coolant pump to the engine and most of them are different lengths.

I like to take a cardboard box and draw an outline of the pump on it, as I remove each bolt I stick it in the cardboard where came off so I will know where to put it back when I put the new pump on.
Figure 12

I like to take a cardboard box and draw an outline of the pump on it, as I remove each bolt I stick it in the cardboard where came off so I will know where to put it back when I put the new pump on.

You can see in this photo from the side how many different length bolts there are and why it is important to keep them in order.
Figure 13

You can see in this photo from the side how many different length bolts there are and why it is important to keep them in order.

Remove the old pump and inspect it for damage.
Figure 14

Remove the old pump and inspect it for damage.

Remember to replace the gasket (red arrow) whether you are installing a new pump or putting the old one back on.
Figure 15

Remember to replace the gasket (red arrow) whether you are installing a new pump or putting the old one back on. Installation is the reverse of removal

Bookmark and Share
Comments and Suggestions:
HAWK Comments: What is the torque for the bolts .
October 17, 2016
  Followup from the Pelican Staff: I don’t have that info.


I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 
Irv Comments: hi I have a 2000 ml320. their are two gaskets included with the pump. your article shows the small one not the flat one. I heard the gasket to use depends on the engine# you have because their were two different covers which were used?
October 6, 2016
  Followup from the Pelican Staff: Match the old gasket up with one of the new ones. Use the one that matches. - Nick at Pelican Parts  
Bosko Comments: Excellent article ! God bless you and reward you for your help!
August 4, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Dave Comments: Thanks for the advice! This time, I did remove both Water pump and the Fan clutch out. Then, I was able to remove the Fan clutch from a defective Water Pump. You know what? Finally, I just followed the instructions from this Article got my car Water Pump replaced without any issues. This is an excellent Article and details...You guys are awesome. Thanks!
May 2, 2016
  Followup from the Pelican Staff: Thanks for sharing your installation process and experience. These type of comments add so much to the Pelican tech community.
- Nick at Pelican Parts
 
Dave Comments: I got a Fan clutch holder and 36 mm Wrench, but have tough time to remove the Fan clutch. I know that the wrench goes CCW and Holder CW to remove, but I never got it loose...Please advise...Overall, I see this Article really helps...
April 17, 2016
  Followup from the Pelican Staff: FOllow the steps in the article. You may have a fan that was over-tightened at some point. Should not be that hard to get off. - Nick at Pelican Parts  
Famousname Comments: AWESOME. This article plus the comments save me about $400 bucks! One thing I'd like to add is be CAREFUL when snugging down the twelve E10 Torx bolts. They are SOFT, so if you torque to much, the head will snap off! Lost three of them before I figured out to take it easy
February 2, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Kiko Comments: Does anyone happen to know what size the small 4 bolts are that hold the water pump pulley to the water pump? Two of them have appeared to have been damaged and I'd like to replace them just to be on the safe side.
January 21, 2016
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
JB Comments: I like your image and article. It is my first time try to replace a water pump on my 2003 mercedess. Wish me luck!!!
January 8, 2016
  Followup from the Pelican Staff: You'll do great!

Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Will-do Comments: Thanks Pelican staff for a really helpful article- and photos, I've completed the water pump uninstall, waiting for the new part to install tomorrow. You are confidence boosters, as well as wallet savers. I'm stoked....
November 29, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Sam I Comments: Do you have an article on replacing an alternator for 2007 Mercedes r350
October 17, 2015
  Followup from the Pelican Staff: We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.

I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 
2001 E320 Comments: All of the bolts attaching the water pump have been removed and the water pump appears stuck to the engine block. Any suggestions?
September 7, 2015
  Followup from the Pelican Staff: Lightly tap the pulley flange with a soft-faced mallet. - Nick at Pelican Parts  
donnie Comments: Thankyou very much, you saved me hundreds of dollars.
August 22, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help. - Nick at Pelican Parts  
Taco Comments: Just changed my water pump using the info provided. Excellent support and knowledge. Thanks alot saved a bunch of money by using this article
July 27, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Taco Comments: What size wrench do I need to remove fan clutch from a 2000 Mercedes ml 320
July 25, 2015
  Followup from the Pelican Staff: 36mm - Nick at Pelican Parts  
Sam Comments: Do you have tech article for replacing the water pump on C230K,1.8K?
April 9, 2015
  Followup from the Pelican Staff:
We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.

I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 
Paul Comments: I just installed the Saleri water pump on my 2004 E320 wagon and these instructions & comments helped tremendously and saved me a lot of work. I highly recommend dry fitting all of the bolts/screws before installing.
One problem with the Saleri was having to create threads on the 2 holes that hold a bracket to the left of the idle pullley. Being very careful I managed to use the e-bolts like self-tapping screws back & forth until bolts created threads. PIA but it eventually worked BEFORE installation.
March 3, 2015
  Followup from the Pelican Staff: Thanks for sharing your installation process and experience. These type of comments add so much to the Pelican tech community.
- Nick at Pelican Parts
 
kriteen Comments: Do we need to use any sealant while replacing the gasket? Or we can directly mount the new pump with gasket onto the block?
October 25, 2014
  Followup from the Pelican Staff: You can use just the gasket, no sealant required. - Nick at Pelican Parts  
Two Screw Comments: on a 2005 w211 e55 do I have to remove the radiator to do this job? I also have the tamper proof bolt on my idler.
September 9, 2014
  Followup from the Pelican Staff: I don't believe so. - Nick at Pelican Parts  
Marcus Comments: The Picture shown by Jimmie is the later style tensioner which has a large socket bolt just below they pulley for taking off the tension
June 27, 2014
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
Shin1ichi Comments: Just changed my first water pump with the Saleri pump i bought from Pelican. Thanks for the great writeup!
**when i started the car, fan came on super high and temp gauge would not work. i found that replugging the temp sensor, the two metal filaments sticking up got pushed down, not inserted. prying them up gently with pocket knife and re-inserting connector corrected problem. Thanks for a great help in allowing me to do this by myself!
June 9, 2014
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Shelli Comments: I am in the process of ordering parts to replace my water pump for my 2002 ML320 & I don't know what all parts that are needed. Can you please tell all parts that are needed for the job! Thanks
May 22, 2014
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799. They can help you find the right part.
- Nick at Pelican Parts
 
mespe Comments: The two bolts in figure 9 do not hold the pump to anything, they just hold the bracket to the pump. Additionally, I would recommend loosening the 4 bolts that hold the water pump pully to the water pump before removing the serpentine.
April 18, 2014
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
BillB Comments: Is their a specific pattern to take while tightening the bolts on install, and what are the torque requirements?
March 26, 2014
  Followup from the Pelican Staff: Always tighten in a criss-cross pattern. I do not have the torque specs handy. - Nick at Pelican Parts  
Dr crow Comments: No heat after Installing new water pump
March 19, 2014
  Followup from the Pelican Staff: I would check coolant level and rebleed the system. - Nick at Pelican Parts  
Jimmie Comments: An E10 reverse torx socket doesn't fit my tensioner. Can you tell me what does fit. Pic attached
March 4, 2014
  Followup from the Pelican Staff: Looks like a tamper proof Torx. Maybe T45 or larger? - Nick at Pelican Parts  
Herb Comments: Excellent article.. I guess its time to try the job.. Cant see $1600 to replace a water pump.. Wish me luck!
November 27, 2013
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Herb Comments: ok I have a Mercedes!
November 25, 2013
  Followup from the Pelican Staff: Cool, thanks. - 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: Wed 12/7/2016 02:30:29 AM