Noisy central locking vacuum pump CLK

[jenmercclk]

Hi Guys

Help! Got a 2001 CLK200 coupe. When central locking releases front doors, the boot remains locked and the vacuum pump whines for about 15 secs before releasing boot. Then, if you try to close the boot within another 15/20 secs it will not close. The whining has stopped at this point. Suspected vacuum leak but nothing apparent. No problem at all with the doors/petrol cap. This happens if you use the boot release switch or the remote or when you open the door after a journey when the doors are on auto lock. Locking is no problem and no whine. . This first happened in the cold weather, then intermittent, now it's all the time and seems to be whining for longer and longer. Anyone got any ideas, don't fancy buying a new pump?

 

[chris846]

check the pin switch - fitted in the lower edge of the boot lid (switches the boot light on and off amongst other things). If it doesn't sense the boot shut properly, then you'll get these symptoms.
chris

 

[jenmercclk]

Looks ok, but just tried locking/unlocking boot with key and it won't turn, wonder if it's a problem with the lock mechanism?

 

[m7m]

Have you checked if the 2 screws holding the lock are tight? They may have become slightly loose with use, causing the lock mechanisin to move slightly from its position.

 

[russpaul]

The pump times out after 10/15 seconds if the required vacuum or pressure is not reached. It generates pressure to unlock and vacuum to lock.If there is a small split in the rubber of the actuator the pump will not reach the required pressure.If you listen carfully around the lock whilst whilst attempting to lock it you may hear an air leek.You will hear a loss of pressure but not vacuum.

 

[russpaul]

There is a good explanation of the central locking here.............Default

Go to ELECTRICAL then RCL/ATA/PSE

 

[jenmercclk]

Noisy central locking vacuum pump

Thanks for your suggestions, will give it a try. Have now got the actual boot lock working on the key, just need to find this elusive leak!

 

[russpaul]

The leak will be on an actuator in one of the doors or trunk lid as all the connecting pipework is extremely durable.

 

[jenmercclk]

Central locking vacuum pump

Cheers, MB devil say you can't buy the actuators, only the whole door/boot lock. Yeah, OK! Don't think so. Would you have any idea if I could get just the actuators off a scrap Merc if I can find one of a similar year, guess the door/boot locks would be the same on most models around 2001? Thanks.

 

[russpaul]

I guess so.I dont know which country you are in and how your scrap yards work but if you have to remove the lock yourself then it would be a good idea to research how to do it first.Once you have removed the lock assembly getting the actuator out is easy.Getting the lock assembly out is the tricky part.It is described in the c class haynes manual as well as the mercedes WIS .Basicaly you have to remove the outer door handle and withdraw its inner mounting plate through the openings in the door (having removed the door trim panel).Three bolts then hold the lock assembly in place.The assembly is removed through the openings.

 

[jenmercclk]

Central locking vacuum pump

Have tracked down the problem to the lock on the petrol filler flap. Got it working intermittently :bannana: and it solved the boot problem and stopped the pump working overtime. What we need to do is remove the plastic fitting and grommet housing the lock in the petrol filler cavity in order to release the actuator in the boot area, but can't seem to remove it from inside the boot. Just wondered if the plastic bit in the filler cavity pulls off, twists or what as worried about breaking it. By the way, I'm in the UK. Thanks very much for your help so far!

 

[russpaul]

I'm sorry bur I've no experience of the CLK but on the c class saloon I recall it unscrews from a bracket and comes away in one piece from inside the boot.

 

[jenmercclk]

After spending hours looking for an air leak, it was the vacuum pump gone faulty. Got a used one for £89 (pretty good price for this particular one). Now all working fine. Thanks for suggestions.