[ezzo]

Hello,
Just an update on the situation for reference. After an intensive research and after consulting a friend mechanic who used to work for a Benz dealership, I cam to the conclusion that the pump must be replaced. Since the oil is coming from the back of the pump housing, then oil has gone inside the pump, which is not supposed to happen. All the internal seals inside the pump are not serviceable.
I hope this can be of value to other people here.

I will bite the bullet and get the C$500 pump in the morning to install. I'll try to post pictures later.

 

[Sleeper Benz]

What is the function of this "Vacuum Pump" for?

 

[Sleeper Benz]

Here's one for @$200 US.

https://www.eeuroparts.com/Parts/55079/Vacuum-Pump-724807410/

Maybe my '04 E500 doesn't have one?

 

[ezzo]

Thanks, Sleeper Benz for this link. I live in Canada, so the Canadian Dollar is different (1 US$ = C$1.33 at the time of writing this) and with duty and customs the price just jumps up. Nevertheless, I was able to get it for a reasonable price from a local parts dealer. I got it from BMV Auto Parts in Vancouver, which is a very nice place, by the way.
The one I got was indeed "Pierburg 724807410" and I am attaching some picture for reference.

I will later post some pictures of the tear down of the old pump.

Cheers for now.

 

[ezzo]

What is the function of this "Vacuum Pump" for?

I think the main function of a vacuum pump is to assist in braking as well as operate different actuators like the ones used for the ventilation and A/C systems. If you have one, it will be at the back of the cylinder head on the driver's side.

 

[ezzo]

This is the "reflection" of the cylinder head socket where the vacuum pump seats. I took this picture after cleaning the oil residue and before installing the new pump.

 

[ezzo]

This is the "reflection" of the cylinder head socket where the vacuum pump seats. I took this picture after cleaning the oil residue and before installing the new pump.

 

[ezzo]

Here are some pictures of the tear down of my old vacuum pump.
Take a look at how much oil went inside!

 

[ezzo]

Here is a couple of animation files for the internals of the vacuum pump.

 

[ezzo]

Here is a couple of animation files for the internals of the vacuum pump.

I guess the size of the GIF files is too big... Here are some pictures instead.

 

[ezzo]

More pictures....

The rotating piece is two parts (a steel core and a plastic fin)

There is a metal vent part (pointed by arrow 1) that is covering a hole (pointed by arrow 2)

 

[ezzo]

One important thing I noticed while taking this pump apart is that the design is inherently inefficient as eventually oil will accumulate inside the pump!

Take a look at the pictures in my previous post and here... so the vent opening that is covered by a flexible metal cover is supposedly meant to let oil out from the pump and back to cam housing?!
But check hole 1 which is supposed to allow oil to go into to the rotating core... but the rotating core has another hole (hole 2 in the picture) and passes oil accross the center to the groove which, in turn, will leak oil inside the pump! I know that Germans are smarter than this but there is no other way oil could have gotten inside the pump!

Since this is a "vacuum" pump, I would expect it to be 100% tightly sealed from all angles to not let either air or oil inside!
If anyone can explain this, I will appreciate it!

Thanks.

 

[ezzo]

Hello,
Just an update on the situation for reference. After an intensive research and after consulting a friend mechanic who used to work for a Benz dealership, I cam to the conclusion that the pump must be replaced. Since the oil is coming from the back of the pump housing, then oil has gone inside the pump, which is not supposed to happen. All the internal seals inside the pump are not serviceable.
I hope this can be of value to other people here.

I will bite the bullet and get the C$500 pump in the morning to install. I'll try to post pictures later.

Here is a couple of pictures of the internal gasket that I had thought I could replace. This is not meant to be replaced!