X300 and 308 Boot lock overhaul

Overhauling the Boot/Trunk lock is an essential maintenance task and requires no special tools or experience and the most frequently requested reason is due to being unable to get into the boot when the battery fails.

Repair Open Time is less than an hour and would cost you here in the UK:
£75.00 at an appointed dealer plus parts
£35.00 If we do it for you plus parts (if you really don’t want to do it yourself)

Use the thumb nail pictures (below right) to view a larger version with highlighted details.

The lock on the boot/trunk of your X300/X308 May not work! Have you tried yours recently? Probably not as most people use the key-ring transmitter to open and close their cars, the boot lock very rarely gets used to open the boot/trunk of the car and often they are seized.

Most often the problem manifests, as the key will only move a small amount clockwise, 12 o’clock to one o’clock when in fact it should go all the way to three o’clock

Having discovered the lock is not working you will need to press the button open the lid and remove the casing over the back side of the boot lid. This is achieved using preferably a trim removal tool, which can be purchased quite cheaply at most good Auto stores. You only need to remove the lower lip ones – 4 in total and that will give you enough access to the lock mechanism. You also need to pop the two plastic covers off the Latch cover and extract the two Torx 30 screws to remove the cover.

The next task is to carefully remove the control rod from the actuating arm. If you click on the picture (Right) you can see that the clip ‘A’ is shown in the closed position. To move it to the extracted position press on tang ‘B’ toward the rear of the boot/trunk lid and press up on tang ‘C’ and extract toward the top. Now move the rod clear by moving it to the left (front edge of boot trunk lid)

Next remove the two 10mm nuts and extract the lock from its location collecting the rubber spacer in the process, which should be found around the forward edge of the lock around the outer edge of the lock mouth

The next step involves removing the C-Clip so you can get the whole thing apart. But mark the location of the cam and note the spring fitment first.

You are now going to need some way to loosen the mechanism up and soaking it in alcohol or turpentine.
We are fortunate enough to have a Ultrasonic bath, but appreciate that this is something the average enthusiast will not have lying around at home. So the process is quite simple for us – drop it in leave it for 20 minutes and the whole thing is freed up. But you will work out your own solution to freeing up the lock, You can use pretty well anything here as you will be re-greasing the lock on reassembly with a graphite grease so removal of any leftover OEM lubricant is of no consequence

  

With the lock now moving its full 90 degree of travel using the key, it is possible to turn the key clockwise very slightly and press on the rear of the barrel to extract it from the casing. This allows removal of the small rod and access to the barrel drum for further cleaning

Once clean reassemble in reverse order but lubricate the moving components with a graphite grease compound as this does not absorb and attract dirt unlike traditional grease

  

Re assemble in reverse sequence When refitting ensure that the rod is located and adjusted as follows: With the lock at rest (no key inserted) hold the opened clip and insert the rod into the receptacle, move the rod until there is no slack before snapping the clip closed.
Test this before closing the boot lid by using a screw driver to flip the catch (see picture right) then use the key to ensure that it unlatches. If it does not adjust the rod again.