Mercedes W123 Diesel Oil And Filter Change Under Car Repair Guide

Difficulty

Easy

Steps

Time Required

                          30 minutes

Sections

Mercedes W123 Diesel Oil and Filter Change, Under Car
14 steps

Flags

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

For this reason you’ll want to change your oil pretty religiously. Some people extend their change intervals to 5,000 miles when using synthetic oil. When using conventional oil it should be changed every 3,000 miles.

Change your filter while you are at it.

As always be careful when handling automotive fluids. Diesel oil, as it is filled with diesel soot, will stain your driveway, your clothes, your skin, and anything else it touches. Wear gloves.

Be sure to also catch the fluid in the proper container and dispose of it properly. Almost every auto parts store will accept used oil and oil filters for proper disposal.

Note that this is just one of two methods. This method has you under the car, removing the drain bolt. Another method is to use a suction device to draw engine oil up and out of the dipstick. The filter change process is the same, regardless of the oil change method used.

What you need

Step 1

              Mercedes W123 Diesel Oil and Filter Change, Under Car

To start, remove the oil cap. This will allow the oil to drain out of the engine faster.

To start, remove the oil cap. This will allow the oil to drain out of the engine faster.

1024

Step 2

Now underneath the car loosen the oil drain bolt. It takes a 13mm socket.
Be aware that once the bolt comes loose the oil will come out very quickly. Have a drain pan ready underneath the oil drain hole.

Now underneath the car loosen the oil drain bolt. It takes a 13mm socket.

Be aware that once the bolt comes loose the oil will come out very quickly. Have a drain pan ready underneath the oil drain hole.

Step 3

Clean up your drain pan bolt. If you are unsure about how old the pan bolt is, it’s best to replace it. Consider replacing it every five or six oil changes. It’s cheap insurance.

Clean up your drain pan bolt. If you are unsure about how old the pan bolt is, it’s best to replace it. Consider replacing it every five or six oil changes. It’s cheap insurance.

Step 4

Wearing gloves during an oil change is a very good idea. As mentioned before, it stains everything. As you can see, even after wiping up, these latex gloves are stained. Imagine what it would do to your skin.

Wearing gloves during an oil change is a very good idea. As mentioned before, it stains everything. As you can see, even after wiping up, these latex gloves are stained. Imagine what it would do to your skin.

Step 5

Next, loosen the two nuts that hold the lid on the oil filter housing. They take a 13mm socket just like the drain plug.

Next, loosen the two nuts that hold the lid on the oil filter housing. They take a 13mm socket just like the drain plug.

Step 6

Once the nuts are loosened and removed, lift the cover up and out of the filter housing. Remove the filter as well.
Be careful as you remove the cover. It can be easy to disconnect some of the vacuum lines that cross over and next to the oil filter housing. If this happens you may cause issues with the vacuum system such as the locks, the shut-off valve, or transmission.
Note that when you remove the oil filter, the bit of oil left in the housing will then drain from the drain plug. Make sure to leave the drain pan underneath until you re-install the drain plug towards the end of the guide.

Once the nuts are loosened and removed, lift the cover up and out of the filter housing. Remove the filter as well.

Be careful as you remove the cover. It can be easy to disconnect some of the vacuum lines that cross over and next to the oil filter housing. If this happens you may cause issues with the vacuum system such as the locks, the shut-off valve, or transmission.

Note that when you remove the oil filter, the bit of oil left in the housing will then drain from the drain plug. Make sure to leave the drain pan underneath until you re-install the drain plug towards the end of the guide.

Step 7

Make sure to keep the oil filter in a suitable container. It will slowly drip dirty oil.

Make sure to keep the oil filter in a suitable container. It will slowly drip dirty oil.

Step 8

The new oil filter kit should come with the filter itself, a choice of new crush washers for the drain plug bolt, and a new large o-ring gasket for the oil filter housing cover.
It’s generally recommended to use the copper crush washer. Copper is a soft metal that crushes well for a good seal.

The new oil filter kit should come with the filter itself, a choice of new crush washers for the drain plug bolt, and a new large o-ring gasket for the oil filter housing cover.

It’s generally recommended to use the copper crush washer. Copper is a soft metal that crushes well for a good seal.

Step 9

It is never a bad time to check parts before installing them. This oil filter was slightly crushed at the bottom during shipping. Another one was used instead.

It is never a bad time to check parts before installing them. This oil filter was slightly crushed at the bottom during shipping. Another one was used instead.

Step 10

Replace the rubber o-ring gasket around the lid of the oil filter housing cover. Never re-use the old one.
Use a small needle nose plier or a small flat blade screwdriver to help remove the old gasket.
Lightly coat the new gasket with some of the new motor oil to help it seal properly.

Replace the rubber o-ring gasket around the lid of the oil filter housing cover. Never re-use the old one.

Use a small needle nose plier or a small flat blade screwdriver to help remove the old gasket.

Lightly coat the new gasket with some of the new motor oil to help it seal properly.

Step 11

Check the o-rings at the tip of the oil filter housing shaft. There are two of them. If they are hardened, or no longer round, they should be replaced. Proper o-rings can be found in any metric o-ring set.
It is good practice to replace these every third or fourth oil change as preventative maintenance.
The ones shown here are very flat, and brittle. They had to be broken off as all of their elasticity was gone. They had been neglected for some time, and they were doing little good as a seal.

Check the o-rings at the tip of the oil filter housing shaft. There are two of them. If they are hardened, or no longer round, they should be replaced. Proper o-rings can be found in any metric o-ring set.

It is good practice to replace these every third or fourth oil change as preventative maintenance.

The ones shown here are very flat, and brittle. They had to be broken off as all of their elasticity was gone. They had been neglected for some time, and they were doing little good as a seal.

Step 12

Install the new filter on the housing lid shaft. Then insert the filter in to the housing and snug the lid down with the two nuts you removed in step 5.

Install the new filter on the housing lid shaft. Then insert the filter in to the housing and snug the lid down with the two nuts you removed in step 5.

Step 13

Now install the drain plug, in this case a new one, with a new crush washer.
While you may re-use the drain plug several times, never re-use the crush washer. It comes with the oil filter, so there’s simply no reason.

Now install the drain plug, in this case a new one, with a new crush washer.

While you may re-use the drain plug several times, never re-use the crush washer. It comes with the oil filter, so there’s simply no reason.

Step 14

It’s time to put in fresh oil. Use a diesel rated oil.
Consult your owner’s manual for what viscosity to use based on your climate. Where this car is located, 15w40 works year round but a thinner oil such as 0w40 could be helpful for cold starts in very cold climates.
Start by putting in about 5 or 5 and 1/2 quarts. Wait a few minutes to let it run down to the oil sump. Then put the oil cap on and start the engine. Make sure oil pressure shows on the gauge fairly quickly. Then let it run for about 1 minute. This will fill the filter housing back up with oil.
Then turn off the car and check the oil level. If it’s low, add no more than 1/2 quart at a time until it’s full. It will take between 6 and 6 and 1/2 quarts. If you want some guidance on checking oil level see the oil level check guide.
Never over-fill a diesel engine with oil. It can lead to catastrophic engine failure due to a runaway engine scenario.

It’s time to put in fresh oil. Use a diesel rated oil.

Consult your owner’s manual for what viscosity to use based on your climate. Where this car is located, 15w40 works year round but a thinner oil such as 0w40 could be helpful for cold starts in very cold climates.

Start by putting in about 5 or 5 and 1/2 quarts. Wait a few minutes to let it run down to the oil sump. Then put the oil cap on and start the engine. Make sure oil pressure shows on the gauge fairly quickly. Then let it run for about 1 minute. This will fill the filter housing back up with oil.

Then turn off the car and check the oil level. If it’s low, add no more than 1/2 quart at a time until it’s full. It will take between 6 and 6 and 1/2 quarts. If you want some guidance on checking oil level see the oil level check guide.

Never over-fill a diesel engine with oil. It can lead to catastrophic engine failure due to a runaway engine scenario.

Be sure to check for leaks after you’ve taken a short test drive.

Cancel: I did not complete this guide.

                                                                                      30 other people completed this guide.

Author

                                      with 2 other contributors

                    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

Dan Gambocorto - Apr 8, 2015

Judging by the listed oil capacity, I’m guessing that the vehicle in the guide has an OM616. What starting / final oil capacity would you suggest for an OM617A (oil-cooled turbo)? I’ve been quoted 7.8qts before.

Nicolas Siemsen - Apr 9, 2015

Actually, this is a OM671a. The 7.8 qt capacity is the original fill capacity when the engine is filled at the factory.

When changing the oil, you’re going to be between 6 and 7 quarts for re-fill as a certain amount of oil (approx a quart) remains in the oil cooler unless you remove the lower oil cooler hose each time you change the oil, which is not generally recommended.

I prefer not to give a specific fill capacity as the better method is to first slightly underfill, then run the engine and check the level before topping off. This ensures that you do not overfill the engine. Being under-filled is less of an issue by far than overfill. Overfill can cause foaming and even a runaway diesel in extreme cases.

daada - Jun 18, 2016

What are the dimension of o-rings in step 11 ???

Introduction#

What you need#

Team#

Introduction

What you need

Team