Difficulty

Moderate

Steps

3

Time Required

                          45 minutes

Sections

1

  • Short Bypass Coolant Hose
  • 3 steps

Flags

0

  • BackMercedes W123

  • Full Screen

  • Options

  • History

  • Save to Favorites

  • Download PDF

  • Edit

  • Translate

  • Get Shareable Link

  • Embed This Guide

  • Notify Me of Changes

  • Stop Notifications

Introduction

Well, if you’re talking about the short coolant hose that connects the thermostat housing to the water pump, it definitely can!

In fact, it’s often one of the first things to leak on your cooling system. Maybe it’s because it’s so short there isn’t much room for failure. Whatever the case, if it’s leaking it’s time to replace it. It’s pretty critical, after all. It carries all of the coolant that flows through the engine when the thermostat is closed during the warm up process.

As always when dealing with automotive fluids you should wear the proper protective gear, such as gloves and glasses. Also be sure to catch the fluid properly and dispose of it safely and in an environmentally sound way!

What you need

Step 1

              Short Bypass Coolant Hose
  • Required: In order to remove your short cooling bypass hose you will first need to remove the thermostat housing. The thermostat housing gasket will need to be replaced, with fresh gasket sealant, at the end of this job. For guidance on removing the housing and replacing the gasket [invalid guide link]

Required: In order to remove your short cooling bypass hose you will first need to remove the thermostat housing. The thermostat housing gasket will need to be replaced, with fresh gasket sealant, at the end of this job. For guidance on removing the housing and replacing the gasket [invalid guide link]

1024

Step 2

  • This is the short coolant hose to be replaced. You can see it leaking in this picture. This is a typical failure.
  • During the thermostat housing removal process you’ll have already loosened the upper hose clamp on the short hose. Now loosen the lower clamp.
  • With the lower clamp removed you’ll be able to pull the short hose off the water pump inlet.
  • Use a pair of pliers for grip if you need to, but it should pull off by hand.

This is the short coolant hose to be replaced. You can see it leaking in this picture. This is a typical failure.

During the thermostat housing removal process you’ll have already loosened the upper hose clamp on the short hose. Now loosen the lower clamp.

With the lower clamp removed you’ll be able to pull the short hose off the water pump inlet.

Use a pair of pliers for grip if you need to, but it should pull off by hand.

Step 3

  • Here is the short hose off of the car.
  • Measure its length, and then mark that length on the bulk hose you purchased.
  • Use a utility knife or other appropriate cutting tool to cut the length of hose you need to replace the old short hose.
  • Install the new hose, and then re-install the thermostat housing and gasket.

Here is the short hose off of the car.

Measure its length, and then mark that length on the bulk hose you purchased.

Use a utility knife or other appropriate cutting tool to cut the length of hose you need to replace the old short hose.

Install the new hose, and then re-install the thermostat housing and gasket.

To reassemble your device, follow these instructions in reverse order.

Cancel: I did not complete this guide.

                                                                                      3 other people completed this guide.

Author

                    Nicolas Siemsen

Member since: 12/06/2013

38,128 Reputation

                                      79 Guides authored                  



                       Badges:
                       30







                                                        +27 more badges

Team

                       Master Techs                        

                                                  Member of Master Techs 



                    Community                     


                                            310 Members                     


                                            1,168 Guides authored

ony632000 - Jul 14, 2016

Reply

I just wanted to say thank you to Nicolas Siemsen for this piece. I am yet to do it because I am yet to buy the piece of hose. But seeing how clearly he wrote the article with pictures I am confident that I can do it. Thanks again.

Nicolas Siemsen - Jul 15, 2016

You’re welcome!

analogcd - Mar 16, 2018

Reply

Tips: Be sure to replace the clamps with new worm-drive type having combination hex-slot screw heads. These are far superior to original type. Also be sure to orient the clamps so screw heads point toward front of car and next to the cylinder head. The latter is necessary for proper clearance as air conditioning bracket sits adjacent to thermostat housing on some versions. Take time to carefully situate the hose clamps as they are almost impossible to access once compressor bracket is in place. Also take time to clean metal surfaces to which the hose connects - lightly sand or scour with metal brush to remove deposits - assuring proper seal is important before assembly.