Hello all, my B170 sunroof was stuck and could not open for more than two years. I learned that this sunroof is very problematic and very very costly to replace with a used one (> RM8K). However, i saw from youtube that there are many tutorial/guidance to repair this sunroof. Two weeks ago, i decided to have a try for DIY repairing. Finally, this DIY is successful and now the sunroof is working like a charm :)
In conclusion, it is not a simple DIY, it required very high skill, very long time (min 5days), and very good passion. And also be prepared to dismantle and install few times to understand the mechanism and make it works correctly.
The broken part is just the plastic part for opening the first reflector slate. However, i have to dismantle the whole sunroof to get to this part. This broken part could be bought from ebay for less than RM200 inclusive delivery:ebay A B Class sunroof repair kit

These plastic parts 100% prone to fail over time. fortunately these are the only plastic parts in sunroof. Other parts are all metal parts which could last for life.

below are tutorial video that i refer to from youtube:
W169 W245 Removal and installing sunroof
W169 W245 replacement of mechanism parts for sunroof
W169 W245 replacement of wind reflector mechanism

The procedure to remove broken part is as below:
Follow step 1~5
step 1: remove mechanism,follow youtube video above
step 2: remove front mechanism,follow youtube video above
step 3: remove 3 screw
step 4: lift down front frame abit to remove broken part for step 5
step 5: remove the broken part in direction toward front.


Remember to apply Silicon grease to all moving parts during installation.

And also apply "Sikaflex 221" to seal the edge of sunroof during complete sunroof installation.

during complete sunroof installation, the step to tighten the screw is as below:
step 1:
tighten sunroof 4 corner screws first!!!
tighten sunroof 4 corner screws first!!!
tighten sunroof 4 corner screws first!!!
(i must say three times, this step is very important, this step is to ensure the height position of sunroof is correct for better water sealing)
Step 2:
Then follow by tightening other screw.
(tighten these other screws will not change the height position of sunroof)



and also the most important is my DIY result photo:



Broken part:


bottom is old part (broken into 3 pieces), upper is new part:


Replace this part also due to crack:


Finally it works