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    
Bookmark and Share

Pelican Technical Article:

Cooling System Leak Test

Nick Czerula

Time:

1.5 hours

Tab:

$20

Talent:

**

Tools:

Cooling system pressure tester

Applicable Models:

Mercedes-Benz E320 (2003-09)
Mercedes-Benz E500 (2003-06)
Mercedes-Benz E55 AMG (2003-06)

Parts Required:

Engine coolant, additional parts will be determined once leak is found

Hot Tip:

Check for leaks with engine warm and cold

Performance Gain:

Repair coolant leaks

Complementary Modification:

Replace associated hoses and cooling system seals

Pressure testing your Mercedes-Benz W211 cooling system is the best way to find leaks. However, not everyone has a pressure tester. I would suggest owning one if you plan to maintain your own vehicles. It can save quite a bit of time when locating a cooling system leak. You can also check for leaks without a pressure tester, but results are less accurate and the procedure is time consuming. I will cover pressure testing in this tech article, as well as some tips on checking for leaks without using one. Always start with a cool engine. If you do not find the leak, warm the engine with the pressure tester installed. At times, leaks will surface, as parts expand from engine heat.

A cooling system pressure tester is used to pressurize a cooling system and hold the cooling system at a specified pressure while looking for leaks. Coolant leaks can be internal (i.e.: head gasket) or external (i.e.: radiator). It is important to take these things into consideration when looking for a coolant leak. If you are losing coolant, but not seeing any on the ground, this would likely be an internal coolant leak. Puddles of coolant found under your vehicle would be from an external leak. Remember to properly clean any coolant that gets on the ground and properly dispose of it. Place a drain pan under suspected areas of leaks to minimize coolant spills. W211 models can develop coolant leaks toward the front of the engine, in places like the radiator hoses, coolant reservoir, water pump and thermostat. A pressure tester is the quickest way to find these leaks.

Remember that your car may have been serviced before and had parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve as they grow older. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Before digging too deep searching for a coolant leak, inspect the coolant reservoir (yellow arrow) and attaching lines and hoses (red arrows).
Figure 1

Before digging too deep searching for a coolant leak, inspect the coolant reservoir (yellow arrow) and attaching lines and hoses (red arrows). The reservoirs can develop hairline cracks. The lines and sealing O-rings on the lines also leak. It's a great place to begin your diagnosis.

When pressure testing a cooling system, be sure that the vehicle is cool and lacks pressure.
Figure 2

When pressure testing a cooling system, be sure that the vehicle is cool and lacks pressure. Then, remove the coolant expansion tank cap.

Once the cap is removed, install the pressure tester adapter (red arrow) to the coolant expansion tank.
Figure 3

Once the cap is removed, install the pressure tester adapter (red arrow) to the coolant expansion tank.

Pressurize the system to 1.
Figure 4

Pressurize the system to 1.5 bar (21.8 psi). Pressure should not drop more than 10% over a two-minute time period. If pressure drops right off, that is a sign of a leak. Look for coolant on the ground. If no coolant reaches the ground, you could have an internal leak. If you suspect a head gasket leak, you need to test the cylinder sealing via a leak down test. If coolant leaks externally, use a flashlight and follow the coolant to the source.

Coolant leaking down the left side of the engine could be the water pump or the thermostat (red arrow).
Figure 5

Coolant leaking down the left side of the engine could be the water pump or the thermostat (red arrow). Coolant down the front right of the engine could be from the coolant temp sensor. From the bottom of the engine, coolant will leak down from the cluster of cooling system components. Coolant leaking down the left side of the engine can be from coolant hoses or the reservoir. Coolant leaking down the radiator could be from the radiator or a radiator hose. If you have an intermittent coolant leakage issue, it may be the hose sealing O-rings. I identified the leak by pressuring the cooling system, then I wiggled the hoses. While wiggling one hose, coolant leaked. When I removed the hose, I found a dislodged O-ring. When looking for leaks at the radiator, inspect the side tanks on the radiator for signs of leaks or fresh coolant. Use a mirror to inspect the bottom of the hoses and connections at the radiator.



Bookmark and Share

  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: Fri 12/9/2016 02:46:54 AM