W123 230e Vacumm Leak

[cdc02254]

I have noticed that there is a vacuum leak on my 230e.

Everything works OK when the car is running all doors lock and unlock but when I go to the car to unlock only the drivers side opens until I start then engine then all doors open.

I have also noticed that there is a hissing sound coming from the rear of the car when I start it, I hadn't though anything of this as it is my first petrol 230e auto so I guessed it might be normal but now thinking about it I guess the car is losing pressure in the vacuum reservoir.

Can anyone direct me what to check first?.

Many thanks in advance.

 

[andymerc]

start at the front at the engine locate which vacuum pipe is leaking you can then look at what is conected to this pipe

 

[jaymanek]

you have a leak in the system somewhere...

If yours is an early system, you will find a plastic thing wedged between the petrol tank and the parcel shelf in the boot.. This is designed to hold the vacuum pressure for the central locking when the car isnt running.
These can often leak.

Also, in the engine bay, just where the pipes go through the firewall there are some one way valves... these also fail which means as soon as you switch the car off, the vacuum pressure is lost.

However any leak in the system will have the same effect. So if you are hearing hissing, I would investigate this first.

Thanks

Jay

 

[vijilants]

Yep,

Consider yourself lucky that you can actually hear the hissing.

This system can be a real nightmare to fault when you cant hear the leak.

 

[219]

Just as long as it isn't the sound of the electric fuel pump underneath at the back of the car you're hearing - this could also be described as a 'hissing sound' .