R129 door locking vacuum pump

[s5tuart]

My refurbished unit has arrived from the USA. I aim to fit it myself but can't seem to find a simple way of removing the vacuum pipe connections from the old unit. I certainly don't want to force anything and break the current pump as I intend to refurbish it with a new motor and sell it on, hopefully recouping some of my costs.

Does anyone know the proper way to remove the vacuum connectors. I have figured out the little manifold that has 3 tubes on it, it's the other single ones that are causing me worry.
Thank you
Stuart

 

[LostKiwi]

I think its an 8mm (or is it 10mm?) spanner which when placed over the pipe (between the pump and pipe connector) allows it to be levered out without damage. The critical thing is to lever the connector straight out.

Incidentally if your pump looks like this both sets of pipes are on a removable manifold. There's a small tab to pull the release the manifold in one go. Each manifold id keyed so will only go back one way and in the correct place.

 

[s5tuart]

Here is a pic of the top...

 

[LostKiwi]

View attachment 39003 Here is a pic of the top...

Ah - very different to mine (which is similar to the one I posted).

 

[s5tuart]

Ah - very different to mine (which is similar to the one I posted).

Indeed...chalk and cheese! I rang my Indie and apparently there are some little slots in the pipe ends that need moving to one side with a screwdriver, then pull the end off the moulding. I'll give it a try in a couple of days.

 

[s5tuart]

Belt and braces, I ordered another unit from the US that has just arrived. I bought the wrong part this time!!!!

I think it's for a 1996/97 car. Back on eBay it goes. I'm going out shortly to try to fit the new "correct" part. I'll report back! Wish me luck!

 

[LostKiwi]

Belt and braces, I ordered another unit from the US that has just arrived. I bought the wrong part this time!!!!

I think it's for a 1996/97 car. Back on eBay it goes. I'm going out shortly to try to fit the new "correct" part. I'll report back! Wish me luck!

What does it look like (or whats the part number?)

 

[s5tuart]

Less than 1/2 hour start to finish!!!

The manifold part with 3 connections on has a little slide-out black key that needs to be pulled out away from the centre of the whole unit. That allows the manifold to lift free. There are 2 electrical plugs. The grey one has a flip over clasp that needs to be undone and the black power one has 2 squeeze tabs to release it.
Removing the 3 main vacuum pipes (yellow, white and yellow/blue) were causing me the most concern but I found them very flexible, not at all brittle as I had expected.
With a 10mm spanner (thanks @LostKiwi ) wedged under the connector and around the base nozzle, and a little prising in one of the little slots with a reasonable sized screwdriver, lifting the spanner against the edge of the whole unit popped the connectors off quite easily.
Job done! I was also concerned that the unit may have needed coding on STAR but no signs of that yet.

 

[s5tuart]

What does it look like (or whats the part number?)

Part number is 129 800 1548

 

[LostKiwi]

Part number is 129 800 1548

View attachment 39218 View attachment 39219

That looks a lot like mine once the manifolds are removed...
I'll check part numbers later

 

[s5tuart]

That looks a lot like mine once the manifolds are removed...
I'll check part numbers later

Cool! I have it on eBay for £325 but only paid total of £287ish for it. As we seem to be the only ones on this thread you can have it for that if it's the correct one for you.
If the manifold and connector is the same but part numbers differ you're welcome to come to rainy Bedford and try it out.

 

[LostKiwi]

Cool! I have it on eBay for £325 but only paid total of £287ish for it. As we seem to be the only ones on this thread you can have it for that if it's the correct one for you.
If the manifold and connector is the same but part numbers differ you're welcome to come to rainy Bedford and try it out.

Looks identical but sadly doesn't appear to be a direct swap (later modified part). Must have electronic differences

 

[s5tuart]

Looks identical but sadly doesn't appear to be a direct swap (later modified part). Must have electronic differences

Well, as said before, you'd be most welcome to give it a try. When I rang Mercedes a while ago the parts guy I spoke to said the different model numbers didn't always mean the parts were different inside, just different suppliers perhaps, or other minor differences in parts inside.
The one I've just fitted to my car didn't have the same part number either (1248 instead of 1288) but works a treat...

 

[jomerc]

Ah - very different to mine (which is similar to the one I posted).

hello,

its a long time since ive posted anything but the picture of the vacuum pump is exactly the same as mine,

ls it possible you could tell me where the white, yellow and green/yellow pipes go please ?

(l took a photo and shame on me l've delated it by accident ) thank you

 

[jomerc]

l have now found an image of my exact model of pump ( 1298001248) with the pipes attached so that

problem is over, now to fit it back and after cleaning everything l'll see it it works.

 

[Chris Taylor]

Hi Jomerc

What were the symptoms of your failed pump.
Mine over runs for 16 seconds after the doors unlock and there is a delay before the glove boxes unlock. Finally after 16 seconds the boot unlocks.

I’m not sure if it’s the circuitry inside the pump or a leak somewhere.

 

[s5tuart]

Hi Jomerc

What were the symptoms of your failed pump.
Mine over runs for 16 seconds after the doors unlock and there is a delay before the glove boxes unlock. Finally after 16 seconds the boot unlocks.

I’m not sure if it’s the circuitry inside the pump or a leak somewhere.

If I recall correctly, over running of the pump is an indication that it’s starting to wear. I remember buying my replacement pump from the USA after failing to fix my old one, then buying the wrong type and selling that on, then finally getting one that was right. The moral of that story is be careful when you buy another one.
My memory is now hazy but I do believe a tired pump can be reconditioned fairly easily and I think I found some answers on YouTube.
Unfortunately mine was beyond that stage

 

[LostKiwi]

Over running of the pump is a sign that pressure is not building sufficiently to turn off. This can be a worn pump or leak in the system.
A common leak point is the vacuum manifold under the bonnet in the module coffin. The manifold cracks around the ball bearing used to seal the ends. A quick way to check is to operate the heater vents. If the heater vents only go to windscreen and side vents the manifold is likely cracked. Seal it with araldite.
Any splits in the pipes can be repaired using windscreen washer pipe to sleeve the broken area. Make sure the two original ends butt together as close as possible.

 

[Chris Taylor]

Thanks Lost Kiwi
The heater seems to work Ok so hopefully the manifold is OK.
Is the coffin you mention the one where the fuse box is located?
I’m awaiting a hand pump that gives positive and negative pressure so I can start testing lines.
Mine is a 1998 280. Hopefully someone will have a replacement pump if mine is at fault. It seems weird that the boot unlocks later than the doors as I believe they are both on the same circuit.

 

[LostKiwi]

View attachment 59158 View attachment 59157 Thanks Lost Kiwi
The heater seems to work Ok so hopefully the manifold is OK.
Is the coffin you mention the one where the fuse box is located?
I’m awaiting a hand pump that gives positive and negative pressure so I can start testing lines.
Mine is a 1998 280. Hopefully someone will have a replacement pump if mine is at fault. It seems weird that the boot unlocks later than the doors as I believe they are both on the same circuit.

Coffin module is passenger side under the plastic cover in front of the windscreen - where the ECUs are hidden in a big metal box. From memory there are 3 screws holding the cover down. Bear in mind that's on my 93 500 so yours may be different.

That white tube from memory goes to the coffin module which also has vacuum supplied from a take off to the inlet manifold. It may be worth blanking that pipe off to verify no issues with the one way valve in the manifold drawing vacuum back via the inlet manifold.