I changed the pollen filter of my 2004 CLK320 yesterday. It was a Mahle carbon filter and it was quite hard to put it in. I practically had to squeeze it.

When I put away the old one, I noticed there is a air flow direction (arrow) on the side of the filter. Now I am not sure if I put it in the right way. After the installaiton, should this arrow point to the hood or the battery?

Also, how often do you guys change this filter?

 

hi,

i change it every 30 000 km. but also depends on the filtering capacity

the arrow if i am not mistaken must point towards the cabin

 

Now that I think of it, due to the shape of the pollen filter, there is only one way to insert the filter so the air flow direction will be correct. Please correct me if I am wrong.

 

Yes, it's not rectangular, so it will only fit one way. For the CLK, I just periodically knock the dust out of the cabin air intake filter. Since I ride topless 90% of the time, changing the dust filter is a somewhat useless exercise. On the C240, I replaced it with an electrostatic filter, I bought it at Home Depot. It's made for a home A/C system, but I cut it to fit the car. Works like a charm - I just wash it out twice a year.